Association between Lower Extremity Movement Patterns and ACL Loading in CAI Patients Across Varied Ankle Sprain Frequencies within a Year

Association between Lower Extremity Movement Patterns and ACL Loading in CAI Patients Across Varied Ankle Sprain Frequencies within a Year | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Association between Lower Extremity Movement Patterns and ACL Loading in CAI Patients Across Varied Ankle Sprain Frequencies within a Year Zeyi Zhang, Shengmeng Wei, Hanlin Shi, youping Sun This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4419864/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 04 Apr, 2025 Read the published version in Journal of NeuroEngineering and Rehabilitation → Version 1 posted 15 You are reading this latest preprint version Abstract Purpose To investigate the relationship between the biomechanical characteristics of lower extremity and anterior cruciate ligament (ACL) loading during single-leg landing in patients with chronic ankle instability (CAI) who have different ankle sprain frequencies within a year. Study Design: Cross-sectional study; Level of evidence, 3. Methods Ankle sprain occurrences among 74 participants were meticulously documented over one year. The participants were systematically classified into groups based on the monitoring data regarding the frequency of ankle sprains over the course of this year, ranging from 2 to 6 or more incidents. Kinematic, kinetic, and electromyographic data were collected while participants performed a single-leg landing task. Lower extremity muscle force and ACL loading were modeled using OpenSim software. Results CAI patients with more than four ankle sprains had higher peak ACL loading during single-leg landing than those with only two or three ankle sprains ( P < 0.05). Additionally, CAI patients with more than four ankle sprains exhibited a limited range of ankle dorsiflexion and biceps femoris muscle strength, which was significantly correlated with ACL loading ( P < 0.05). CAI patients with more than 5 ankle sprains had greater ankle inversion angle, inversion angular velocity, vertical ground reaction force (GRF), rectus femoris muscle strength, and lower gastrocnemius, soleus muscle force during single-leg landing, and these biomechanical indices were significantly correlated with ACL strain ( P < 0.05). Conclusion Based on these findings, it appears that experiencing four ankle sprains within a year might be a threshold for the development of knee compensation in CAI patients. This compensation could result in a significant increase in ACL loading. The study also found that CAI patients with more than four ankle sprains commonly exhibited altered motor characteristics such as limited ankle dorsiflexion angle, increased ankle inversion angle, excessive vertical GRF, and insufficient gastrocnemius and soleus muscle force during the landing phase. These characteristics might be responsible for the observed increase in ACL loading. ankle sprain frequencies CAI patients ACL loading biomechanics OpenSim modelling Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Key points Findings Patients with CAI who have experienced more than four ankle sprains within a year exhibited severe knee compensation and increased ACL load during single-leg landing. Limited ankle dorsiflexion, increased ankle inversion angle, excessive vertical GRF, and insufficient gastrocnemius and soleus muscle strength might increase ACL load in patients with CAI who have experienced more than four ankle sprains within a year. Implications Individuals with a history of more than four ankle sprains should undergo a thorough examination of knee health and receive regular monitoring to prevent the development of ACL injuries. Patients with more than four ankle sprains within a year should focus on increasing ankle dorsiflexion, performing rehabilitation of the ankle evertor, plantar flexor, and hamstring, and consider adjusting the energy absorption patterns of the lower extremity joints to more effectively cushion GRF. Caution This study only explored participants who had experienced 2, 3, 4, 5 or 6 or more ankle sprains, and future studies could further subdivide the “6 or more” category so that the results of the study can be more targeted. 1 Introduction Ankle sprains are a prevalent type of lower extremity injury, with 11.88% of cases occurring during sports activities [ 1 ] . Regrettably, without proper rehabilitation, around 73% of patients developed chronic ankle instability (CAI) [ 2 ] . CAI is characterized by lateral ankle ligament laxity, pain, swelling and ankle dysfunction. An ankle sprain increases the likelihood of recurrent ankle sprains [ 3 ] A systematic review found that 68 ~ 78% of CAI patients experience recurring ankle sprains due to impaired balance and neuromuscular control of the affected lower extremity during exercise, which significantly reduces the quality of life and participation in sports [ 4 ] . Prolonged repetitive ankle sprains can damage mechanical receptors in the joint capsule [ 5 ] . This can disrupt electrical conduction between the mechanoreceptors and the central nervous system, leading to a significant reduction in ankle position and motion perception, which impairs control of the joint and the ability to cushion foot landings [ 5 ] . Moreover, it might trigger proximal adaptive responses that increase the risk of knee injuries, particularly anterior cruciate ligament (ACL) injuries [ 5 ] . Research has shown that between 52% and 60% of patients with ACL injuries report symptoms related to CAI [ 5 ] . In a 6-month health survey of 146 female footballers, Soderman and colleagues found that 60% of ACL-injured players suffered recurrent ankle sprain [ 6 ] . Therefore, a number of studies have attempted to investigate the biomechanical mechanisms that make patients with CAI more susceptible to ACL injury. These studies, both domestically and internationally, have typically used OpenSim modeling software to calculate dynamic ACL loads, which is a widely utilized and accurate method [ 7 ] . Delahunt et al [ 8 ] found that patients with CAI experienced significantly limited ankle dorsiflexion during the landing phase compared to healthy subjects. Furthermore, knee flexion angle was significantly reduced during initial contact [ 9 ] . These biomechanical changes might increase the angle between the patellar tendon and the tibial shaft, leading to greater anterior tibial shear forces, which increase susceptibility to ACL injuries [ 9 ] . However, other research investigated the movement strategies of lower extremities during single-leg landing in patients with CAI and found that they often exhibit larger ankle dorsiflexion angle, knee flexion angle, and hip flexion angle than do healthy individuals and Copers [ 10 ] . Simpson et al [ 11 ] . conducted a systematic study and found that patients with CAI exhibited prolonged activation latency of the peroneus longus and piriformis muscles during the landing phase. This reduced the cushioning effect of the ankle against the medial-lateral ground reaction force (GRF), which in turn led to an increase in knee loading and thus higher ACL loads [ 12 ] . However, a study that analyzed the forces and energy dissipation in the lower extremity of CAI patients during vertical jump landing. The findings elucidated a noteworthy revelation: the knee joint experienced lower loads compared to other joints in individuals with CAI [ 13 ] . As indicated by these varied reports, the biomechanical mechanism that made CAI patients more susceptible to ACL injuries is not well understood. This might be due, in part, to the fact that none of the studies mentioned above took into account the ankle sprain frequency of CAI patients [ 8 , 9 , 10 , 11 , 13 ] . Previous research has shown that the number of self-reported previous sprains was associated with ankle dysfunction and instability, particularly in individuals with two or more prior ankle sprains, who exhibit reduced ankle function and stability compared to the single ankle sprain group [ 14 ] . Additionally, the number of previous ankle sprains in CAI patients was positively correlated with the severity of ACL injuries, with a χ 2 value of up to 5.27 [ 15 ] . The objective of this study was to compare lower extremity biomechanics in CAI patients across different ankle sprain frequencies within a year. Additionally, the relationship between these biomechanical characteristics and ACL strain was analyzed. The present study hypothesizes that patients with CAI who have experienced more frequent ankle sprains might experience increased ACL loading. Additionally, this population exhibited insufficient ankle dorsiflexion angle, gastrocnemius muscle force, soleus muscle force, and greater ankle inversion angle, inversion angle velocities during single-leg landing, which might result in an increase in ACL loading. The results of this study may help to identify the threshold at which CAI patients begin to experience knee compensation, and provide a scientific reference for future studies to evaluate potential associations between ankle sprain and ACL injury. 2 Methods 2.1 Study design This study monitored the ankle sprains frequency within a year among individuals with CAI, categorizing them into groups with 2, 3, 4, 5, and 6 or more occurrences of ankle sprains. Biomechanical tests were conducted to analyze the reasons for knee joint compensation among CAI patients with different ankle sprains frequencies within a year. This research was conducted at the Key Laboratory of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, East China Normal University, April 2023. 2.2 Participants The study participants were chosen according to the International Ankle Consortium’s criteria for identifying patients with CAI [ 16 ] . Participants were included in the study if they satisfied the following criteria: 1) Participants were required to have experienced at least one ankle sprain that resulted in ≥ 1-day interruption of physical activity and was associated with inflammatory symptoms (e.g., pain, swelling). Furthermore, participants must have suffered an initial ankle sprain at least 12 months previously, the most recent of which having occurred at least 3 months before the experiment; 2) On at least two occasions, participants must have experienced their ankle “giving way” due to repeated (two or more) ankle sprains of the affected ankle within the six months prior to the experiment, and each individual’s Cumberland Ankle Instability Scale (CAIT) score must have been less than 24; and 3) their Foot and Ankle Ability Measure (FAAM)-Activities of Daily Living (ADL) scale score had to be less than 90%, and their FAAM-Sport scale score had to be less than 80%. Additionally, their Foot and Ankle Outcome Score (FAOS) score had to be less than 75% in three or more categories. Exclusion criteria for participation in the experiment included the following: 1) Participants had a history of previous surgeries to the musculoskeletal structures (ie, bones, joint structures and nerves) in either lower extremity; 2) Participants had a history of lower extremity fracture; and 3) Within 3 months prior to the experiment, participants had an acute injury to the joint structures of the lower extremity that compromised the integrity and function of the joints and resulted in cessation of physical activity for at least 1 day. In this investigation, 80 CAI patients were enlisted into the study one year antecedent to the formal biomechanical assessments. Throughout this interim, any instances of ankle sprains encountered during participants' routine activities were expeditiously relayed to the testers through the WeChat platform (Tencent, China). The testers meticulously documented the frequency of ankle sprains experienced by each participant within the one-year interval. Subsequently, participants were stratified into groups based on the frequency of ankle sprains occurring within the specified time frame, categorized as 2, 3, 4, 5, or greater than 6 instances of injury history. However, one participant was excluded due to a history of lower extremity fractures, while five others were unable to participate in the formal experiment for personal reasons, resulting in a final participation count of 74 individuals (Fig. 1). All participants carefully read the protocol of this experiment, understood the experimental procedure and signed the informed consent form. Basic anthropometric tests, including gender, age, height, weight, CAIT score, FAAM-ADL score, FAAM-Sport score and FAOS score were performed on the subjects prior to the formal experiment, and the results are shown in Table 1 . Table 1 Demographics of participants (mean ± SD) Number of ankle sprains/(times) 2 3 4 5 6 or more Sample size/(n) 15 15 15 15 14 gender male male male male male Age/(year) 22.1 ± 1.3 21.6 ± 0.9 23.0 ± 2.0 20.8 ± 2.2 21.4 ± 1.4 Height/(cm) 175.1 ± 7.1 176.9 ± 7.1 177.3 ± 4.8 176.7 ± 6.7 175.9 ± 7 .0 Weight/(kg) 71.2 ± 6.2 71.4 ± 8.6 70.9 ± 6.4 73.8 ± 8.6 75.8 ± 9.7 CAIT score 21.8 ± 1.9 20.8 ± 1.6 20.4 ± 2.3 17.5 ± 1.9 17.1 ± 2.2 FAAM-ADL score/(%) 81.5 ± 5.9 82.0 ± 6.1 77.9 ± 6.4 78.5 ± 6.8 79.9 ± 5.2 FAAM-Sport score/(%) 69.0 ± 4.9 70.1 ± 6.3 68.2 ± 6.3 68.9 ± 5.9 67.5 ± 5.2 FAOS score/(%) Symptom/(%) 69.8 ± 4.2 68.1 ± 5.7 66.9 ± 7.3 67.6 ± 7.1 66.2 ± 5.9 Pain/(%) 72.6 ± 9.7 72.9 ± 8.8 71.2 ± 11.3 68.7 ± 10.3 69.3 ± 9.5 Activities of Daily Living/(%) 81.9 ± 3.6 78.4 ± 5.6 79.7 ± 5.1 80.2 ± 4.2 78.9 ± 6.6 Sport/(%) 70.4 ± 3.5 70.7 ± 3.8 68.4 ± 5.7 66.9 ± 4.9 68.7 ± 4.2 Quality of Life/(%) 70.9 ± 4.7 73.2 ± 6.3 66.4 ± 5.2 68.7 ± 7.8 65.8 ± 3.5 2.3 Test Apparatus 2.3.1 Motion capture system In this study, 12 Vero v2.2 infrared cameras (Vicon, USA) and a motion capture system with a 14 mm infrared marker ball were used to record single-leg landing maneuvers. The cameras were positioned at a height of 2.5 m and used a sampling frequency of 100 Hz. 2.3.2 Three-dimensional force plate In this study, two 40 cm × 60 cm Kistler 3D force plates (Kistler Inc., Switzerland) were used to record the GRF of the subjects during single-leg landing with a sampling frequency of 1 kHz. 2.3.3 Surface EMG testing system The surface electromyography (EMG) device used in this paper was the Telemyo 2400DTS sEMG wireless telemetry system (Noraxon, USA) that contained a 32-channel signal collector, a USB data transfer interface and a wireless receiver card that either could be connected wirelessly or via a cable to a computer. For surface EMG testing, it was often used in conjunction with electrodes and pre-amplifiers. 2.4 Experimental Design and Testing Procedures Before the formal experiment, to ensure optimal adhesion of electromyography electrodes, the designated areas underwent meticulous hair removal. Additionally, participants were provided with uniform shorts, vests and sports shoes, and performed uniform warm-up movements, including jogging, deep squatting, lunging, longitudinal jumping, direction-change running, etc. The warm-up time was 10 minutes. Afterward, testers provided a detailed explanation of the essentials of the test movements to the subjects, and sufficient time was allowed for practice. After the preparatory work was completed, the reflective marker ball and the electrodes were uniformly attached to the participants, and static calibration data were collected. The static calibration movements are shown in Fig. 2. Markers were attached to 39 bony marker points, including the left anterior head, right anterior head, 7th cervical vertebra, 10th lumbar vertebra, left anterior superior iliac spine, right anterior superior iliac spine, left posterior superior iliac spine, right posterior superior iliac spine, knees, thighs, calves, ankle joints, toes, heels, etc. The electrodes were attached to 8 lower limb muscles including the biceps femoris, rectus femoris, vastus lateralis, vastus medialis, gastrocnemius, soleus, peroneus longus and tibialis anterior in accordance with Surface Electromyography for the Non-Invasive Assessment of Muscle (SENIAM) guidelines [ 17 ] . At the start of the formal test, CAI patients were asked to stand on a 40 cm high test platform with the affected leg and hands naturally falling to either side. After the infrared camera started recording, participants dropped onto the force platform with a single leg, subsequently maintaining body equilibrium for a minimum of three seconds post-grounding [ 18 ] . Instances of secondary movement post-grounding resulting in an inability to sustain balance were excluded from data analysis. (Fig. 2). They rested for one minute and repeated the same maneuver four times, resulting in a total of five valid data sets. 2.5 Data Extraction and Preparation This section describes analyses of the biomechanical data from the moment of landing, when the force value on the platform exceeded 10 N, to the moment of maximum knee flexion. Data from the marked points and the GRF data were collected and processed using Vicon software (Vicon Industries, Inc., USA). The original data were smoothed using a fourth order Butterworth filter with cut-off frequencies of 10 Hz and 100 Hz for the marker and GRF data, respectively. The midpoint of the line connecting the medial and lateral femoral condyle markers was defined as the center of the knee joint, and the midpoint of the line connecting the medial and lateral ankle markers was defined as the center of the ankle joint [ 19 ] . EMG signal data were processed using Matlab 2016b software, including applying a Butterworth band-pass filter with frequencies ranging from 10 Hz to 400 Hz, full-wave rectification, and low-pass filtering with a cut-off frequency of 6 Hz [ 19 ] . The kinematic and kinetic data were exported to a c3d format file, converted to mot (Multiple Object Tracking) and trc (Track Row Column) formats using the c3dExport.m package in Matlab 2016b, and then imported into OpenSim 4.1. In this study, the Gait_2354 model in OpenSim was used and the ACL was added to this model. The ACL model extended from the anterior fossa of the tibial condyle to the lateral condyle of the femur, and represented a passive nonlinear elastic soft tissue along the direction of the ligament starting and ending points. The ACL was set up as a passive tissue, with activation of contractile elements being inhibited (Fig. 3). In OpenSim, we first constructed a generic model based on the subject’s height, weight and muscle data, and then scaled the length and mass of the segments 1 using the marker point data obtained from the experiment (Scaling Model, SM). Furthermore, we verified the optimality of the model by finding the best-fit model for the data through inverse kinematics. The process primarily utilized the weighted least squares method to compute the disparities between the experimentally measured 3D coordinates of the marker points, the coordinate system, and the model coordinates, and to minimize these disparities. Force residuals ( Fresidual ) represented discrepancies between the experimental mechanical data and the simulation results. The Reduce Residuals Algorithm in OpenSim could reduce the residuals by optimizing the trajectory and making adjustments to the coupling quality and other variables. The maximum permissible force error was generally between 0 and 10 N, and the maximum permissible torque error was between 0 and 50 N. In addition, Calculate Muscle Control was used to simulate lower extremity muscle force and ACL load. Finally, the kinematic, kinetic and muscle activation data from OpenSim simulations were compared with experimental data in this study using the validation method proposed by Błażkiewicz et al [ 20 ] . OpenSim simulations were considered accurate if differences between residual pelvic forces and peak residual moments derived from OpenSim simulations and experimental measurements did not exceed 20 N and 75 N⋅m, respectively, and EMG curves were similar. 2.6 Experimental Indicators 1) ACL load was defined as the force on the ACL during human movement. It was derived from OpenSim modeling and normalized to a multiple of body weight (BW). 2) Joint angle was defined as the angle between adjacent hinges. Knee angle was defined as the angle between the thigh hinge and calf hinge, and ankle angle was defined as the angle between the calf hinge and the foot hinge. 3) Joint angular velocity is the angular displacement of the hinge around the joint’s center per unit of time and was usually derived from differentiation of angular displacement and time. 4) GRF is the force generated when the human body strikes the ground and was directly measured by the three-dimensional force plates. As GRF was strongly influenced by body weight, it was normalized by body weight. 5) Muscle force was defined as the force generated by muscle contraction during lower extremity movement and was derived from OpenSim modeling. As lower extremity muscle force during single-leg landing might be affected by body weight, muscle force was also normalized by body weight. 2.7 Statistical Analysis The study expressed all index data as mean ± standard deviation (SD) and used an independently designed one-way ANOVA to compare differences in lower extremity joint kinematics, kinetics, muscle strength, and ACL loading between CAI patients who experienced 2, 3, 4, 5, and 6 or more ankle sprains, with the significance level set at P < 0.05. The effect size of the one-way ANOVA, η 2 , was calculated. A low effect size was indicated by 0.01 ≦ η 2 < 0.06, a medium effect size by 0.06 ≦ η 2 < 0.14, and a high effect size by η 2 ≧ 0.14 [ 21 ] . Pearson’s correlation analysis was used to further investigate the relationship between lower extremity kinematics, kinetics, muscle strength and ACL loading in CAI patients. The correlation coefficient |r| ≥ 0.50 was considered high, 0.50 > |r| ≥ 0.30 was moderate, and 0.30 > |r| ≥ 0.10 was low. 3 Results 3.1 ACL Loading Figure 4 shows that CAI patients with 4 ankle sprains (4 sprains vs. 2: F [1,72] = 4.812, P = 0.003, η 2 = 0.218; 4 vs. 3: F [1,72] = 4.812, P = 0.005, η 2 = 0.218), 5 sprains (5 vs. 2: F [1,72] = 4.812, P = 0.008, η 2 = 0.218; 5 vs. 3: F [1,72] = 4.812, P = 0.012, η 2 = 0.218), or 6 or more sprains (6 vs. 2 : F [1,72] = 4.812, P = 0.005, η 2 = 0.218; 6 vs. 3: F [1,72] = 4.812, P = 0.007, η 2 = 0.218) had a significantly greater peak ACL load during single-leg landing than CAI patients with only 2 or 3 ankle sprains. 3.2 Kinetics, Kinematics and Muscle Force of the Lower Extremity As shown in Fig. 5, patients with CAI who suffered 4 sprains (4 vs. 2: F [1,72] = 6.394, P = 0.001, η 2 = 0.270; 4 vs. 3: F [1,72] = 6.394, P = 0.001, η 2 = 0.270), 5 sprains (5 vs. 2: F [1,72] = 6.394, P = 0.001, η 2 = 0.270; 5 vs. 3: F [1,72] = 6.394, P = 0.001, η 2 = 0.270), or 6 or more sprains (6 vs. 2: F [1,72] = 6.394, P = 0.015, η 2 = 0.270; 6 vs. 3: F [1,72] = 6.394, P = 0.012, η 2 = 0.270) exhibited a significantly lower ankle dorsiflexion angle during single-leg landings than those who suffered only 2 or 3 ankle sprains. Furthermore, CAI patients with 5 ankle sprains exhibited a significantly greater ankle inversion angle during single-leg landing than those with only 3 (F [1,72] = 3.741, P = 0.045, η 2 = 0.178) or 4 (F [1,72] = 3.741, P = 0.039, η 2 = 0.178). The ankle inversion angle during single-leg landing was significantly greater in patients with CAI who had experienced 6 or more ankle sprains than those who had only experienced 2 (F [1,72] = 3.741, P = 0.010, η 2 = 0.178), 3 (F [1,72] = 3.741, P = 0.004, η 2 = 0.178), or 4 (F [1,72] = 3.741, P = 0.003, η 2 = 0.178) sprains. Additionally, patients who had experienced 5 ankle sprains also had a significantly greater ankle inversion angle than those who only experienced 2 (F [1,72] = 3.741, P = 0.010, η 2 = 0.178), 3 (F [1,72] = 3.741, P = 0.004, η 2 = 0.178) or 4 (F [1,72] = 3.741, P = 0.003, η 2 = 0.178) sprains. Furthermore, the study found that CAI patients who experienced 5 sprains (5 vs. 2: F [1,72] = 5.230, P = 0.005, η 2 = 0.233; 5 vs. 3: F [1,72] = 5.230, P <0.001, η 2 = 0.233; 5 vs. 4: F [1,72] = 5.230, P = 0.006, η 2 = 0.233) or more than 6 (6 vs. 2: F [1,72] = 5.230, P = 0.030, η 2 = 0.233; 6 vs. 3: F [1,72] = 5.230, P = 0.003, η 2 = 0.233; 6 vs. 4: F [1,72] = 5.230, P = 0.032, η 2 = 0.233) had a significantly greater knee inversion angle during single-leg landing than those who experienced only 2, 3, or 4 ankle sprains. Figure 6 shows that CAI patients with 5 ankle sprains had a significantly greater ankle inversion angular velocity during single-leg landing than those with only 3 (F [1,72] = 1.624, P = 0.025, η 2 = 0.086) or 4 (F [1,72] = 1.624, P = 0.050, η 2 = 0.086) sprains. Vertical GRF was greater in CAI patients with 5 (5 vs. 2: F [1,72] = 6.309, P < 0.001, η 2 = 0.268; 5 vs. 3: F [1,72] = 6.309, P = 0.001, η 2 = 0.268; 5 vs. 4: F [1,72] = 6.309, P = 0.001, η 2 = 0.268) or more than 6 sprains (6 vs. 2: F [1,72] = 6.309, P = 0.005, η 2 = 0.268; 6 vs. 3: F [1,72] = 6.309, P = 0.018, η 2 = 0.268; 6 vs. 4: F [1,72] = 6.309, P = 0.015, η 2 = 0.268) than CAI patients with only 2, 3, or 4 sprains (Fig. 7). Figure 8 shows that CAI patients with 4 ankle sprains had greater strength in the long head of the biceps femoris muscle than those with 2 (F [1,72] = 2.455, P = 0.016, η 2 = 0.125), 3 (F [1,72] = 2.455, P = 0.030, η 2 = 0.125), 5 (F [1,72] = 2.455, P = 0.010, η 2 = 0.125), or 6 or more (F [1,72] = 2.455, P = 0.017, η 2 = 0.125) sprains. Additionally, CAI patients with 5 (5 vs. 2: F [1,72] = 6.199, P = 0.002, η 2 = 0.264; 5 vs. 3: F [1,72] = 6.199, P = 0.002, η 2 = 0.264; 5 vs. 4: F [1,72] = 6.199, P = 0.001, η 2 = 0.264) or 6 or more (6 vs. 2: F [1,72] = 6.199, P = 0.003, η 2 = 0.264; 6 vs. 3: F [1,72] = 6.199, P = 0.003, η 2 = 0.264; 6 vs. 4: F [1,72] = 6.199, P = 0.001, η 2 = 0.264) ankle sprains had significantly greater rectus femoris muscle strength during single-leg landing than those with only 2 or 3 sprains. Furthermore, CAI patients who experienced 5 (5 vs. 2: F [1,72] = 3.644, P = 0.030, η 2 = 0.174; 5 vs. 3: F [1,72] = 3.644, P = 0.007, η 2 = 0.174; 5 vs. 4: F [1,72] = 3.644, P = 0.019, η 2 = 0.174) or 6 or more (6 vs. 2: F [1,72] = 3.644, P = 0.035, η 2 = 0.174; 6 vs. 3: F [1,72] = 3.644, P = 0.008, η 2 = 0.174; 6 vs. 4: F [1,72] = 3.644, P = 0.023, η 2 = 0.174) sprains exhibited reduced gastrocnemius muscle strength during single-leg landings than those who had only 2 to 4 ankle sprains. Additionally, those with 5 (5 vs. 2: F [1,72] = 8.146, P = 0.001, η 2 = 0.321; 5 vs. 3: F [1,72] = 8.146, P < 0.001, η 2 = 0.321; 5 vs. 4: F [1,72] = 8.146, P < 0.001, η 2 = 0.321) or 6 (6 vs. 2: F [1,72] = 8.146, P = 0.001, η 2 = 0.321; 6 vs. 3: F [1,72] = 8.146, P < 0.001, η 2 = 0.321; 6 vs. 4: F [1,72] = 8.146, P = 0.001, η 2 = 0.321) sprains exhibited significantly lower soleus muscle force during single-leg landing than those with only 2–4 ankle sprains. The study found significant positive correlations between force produced by the long head of the biceps femoris muscle (r = 0.532, P = 0.041) during single-leg landing and ACL load in patients with CAI who had experienced 4 ankle sprains. Additionally, the dorsiflexion angle of the ankle was significantly negatively correlated with ACL load (r = − 0.707, P = 0.003). In CAI patients with five ankle sprains, ankle inversion angle (r = 0.750, P = 0.001), ankle inversion velocity (r = 0.538, P = 0.039), and vertical GRF (r = 0.761, P = 0.001) during single-leg landing were significantly positively correlated with ACL load. Conversely, ankle dorsiflexion angle (r = − 0.765, P = 0.001), gastrocnemius muscle force (r = − 0.565, P = 0.028), and soleus muscle force (r = − 0.762, P = 0.001) were negatively correlated with ACL loading. In patients with CAI who experienced more than 6 ankle sprains, ankle inversion angle (r = 0.808, P < 0.001), knee varus angle (r = 0.720, P = 0.004), vertical GRF (r = 0.550, P = 0.041), and rectus femoris muscle strength (r = − 0.863, P < 0.001) were positively correlated with ACL load, whereas ankle dorsiflexion angle (r = − 0.640, P = 0.014) and soleus muscle force (r = − 0.763, P = 0.002) was negatively correlated with ACL load (Table 2 ). Table 2 Correlation of lower extremity kinematics, kinetics, and muscle strength with ACL load in patients with CAI Index ACL loading 2 sprains 3 sprains 4 sprains 5 sprains 6 or more sprains r P r P r P r P r P Ankle dorsiflexion angle −0.024 0.934 0.077 0.786 −0.707 0.003 −0.765 0.001 −0.640 0.014 Ankle inversion angle 0.262 0.346 0.072 0.798 −0.009 0.974 0.750 0.001 0.808 < 0.001 Ankle internal rotation angle 0.010 0.972 0.174 0.536 0.197 0.482 0.006 0.982 0.715 0.004 Knee flexion angle 0.005 0.987 −0.196 0.484 0.378 0.165 0.265 0.340 −0.184 0.530 Knee varus angle −0.591 0.020 0.341 0.214 −0.279 0.313 0.418 0.121 0.720 0.004 Knee internal rotation angle 0.363 0.184 −0.268 0.334 0.026 0.928 0.343 0.211 −0.007 0.981 Ankle plantarflexion angular velocity 0.026 0.927 −0.094 0.739 0.124 0.659 0.446 0.095 0.441 0.114 Ankle inversion angular velocity 0.593 0.020 0.472 0.076 0.534 0.040 0.538 0.039 −0.144 0.623 Ankle internal rotation angular velocity −0.057 0.840 −0.149 0.596 0.338 0.217 0.022 0.937 0.335 0.241 Knee flexion angular velocity 0.375 0.168 0.316 0.251 0.109 0.698 −0.019 0.947 0.025 0.931 Knee inversion angular velocity 0.379 0.164 0.652 0.008 0.260 0.349 0.655 0.008 0.311 0.279 Knee internal rotation angular velocity 0.059 0.835 0.442 0.099 0.311 0.260 0.495 0.061 0.560 0.037 Anterior-posterior GRF 0.423 0.116 0.732 0.002 0.665 0.007 −0.060 0.832 0.411 0.144 Medial-lateral GRF −0.544 0.036 −0.582 0.023 −0.380 0.163 −0.816 < 0.001 −0.725 0.003 Vertical GRF 0.605 0.017 0.251 0.367 0.205 0.464 0.761 0.001 0.550 0.041 Long head of biceps femoris strength −0.406 0.133 0.305 0.270 0.532 0.041 −0.416 0.123 −0.163 0.578 Short head of biceps femoris strength 0.498 0.059 0.178 0.526 0.018 0.950 0.123 0.663 −0.432 0.123 sartorius muscle strength 0.867 0.000 0.313 0.255 0.622 0.013 0.337 0.219 −0.173 0.555 Gracilis muscle strength 0.417 0.122 0.234 0.400 −0.094 0.740 −0.119 0.672 −0.059 0.841 rectus femoris muscle strength 0.715 0.003 0.423 0.116 0.189 0.501 −0.042 0.882 0.863 < 0.001 gastrocnemius muscle strength −0.041 0.883 0.007 0.979 0.042 0.881 −0.565 0.028 −0.763 0.002 Soleus muscle strength 0.505 0.055 −0.056 0.842 0.273 0.325 −0.762 0.001 −0.377 0.184 Tibialis posterior muscle strength 0.206 0.464 −0.165 0.556 −0.070 0.804 −0.092 0.746 −0.003 0.992 Tibialis anterior muscle strength −0.017 0.952 −0.316 0.251 −0.346 0.207 −0.478 0.072 −0.032 0.914 4 Discussion The study results indicate that CAI patients who have experienced more than four ankle sprains exhibited increased ACL loading during single-leg landing. This finding supported the study’s hypothesis, which suggested that knee joint compensation in CAI patients primarily occurred after four ankle sprains. This paper reported that ankle dorsiflexion was limited during the landing phase in patients with CAI who had more than four ankle sprains. This might be due to excessive tension in the non-contractile tissues or degenerative lesions of the ankle joint caused by multiple sprains, which might reduce the flexibility of the anterior-posterior sliding of the talus and affect the brain’s ability to perceive the distance between the talus and the malleolus [ 22 ] . These alterations ultimately result in reduced ankle dorsiflexion [ 22 ] . The study results revealed that decreased ankle dorsiflexion angle leads to a substantial increase in ACL load in CAI patients. Previous research had demonstrated that reduced ankle dorsiflexion angle during landing reduced the proportion of energy absorbed and dissipated in the ankle joint. As a result, the remaining GRF was transferred to the knee joint, leading to knee joint energy compensation [ 23 ] . Meanwhile, based on the sagittal plane coupling theory of lower extremity joints, limited ankle dorsiflexion angle often accompanies reduced knee flexion displacement during landing [ 23 ] . These biomechanical changes might increase the angle between the patellar tendon and the tibial shaft, causing the knee to bear greater anterior tibial shear force and increasing ACL loading [ 9 ] . Hagins et al [ 24 ] conducted a study that confirmed the aforementioned theory. They discovered that limited ankle dorsiflexion significantly increased knee valgus displacement. These biomechanical changes increased ACL load. Therefore, it is recommended that dorsiflexion stretching exercises, plantarflexor relaxation training, or dorsiflexor strength training should be used to increase ankle dorsiflexion and reduce knee compensation during landing in CAI patients with more than four ankle sprains [ 22 ] . It has been reported that a single session of ankle release therapy could also significantly improve the neuronal excitability of the soleus muscle and the static postural control of the lower extremity. Therefore, therapy can significantly improve ankle function in patients with CAI [ 8 ] . In addition, the study revealed that CAI patients with more than 5 ankle injuries had a greater ankle inversion angle during single-leg landing, which might be due to joint kinematics and positioning deficits that made it difficult for them to accurately return the ankle to a neutral orientation, resulting in landing with an inverted posture [ 25 ] . The meta-analysis showed that CAI patients had moderate or mild eversion muscle weakness at centripetal contraction velocities between 30°/s and 120°/s. This weakness might be a significant contributing factor to the increased ankle inversion angle, which in turn further contributed to the increased knee inversion angle due to the presence of kinematic chains in the joints of the lower extremity. The above kinematic characteristics were significantly correlated with ACL loading. The reason for this was that the ACL was pre-strained in the inverted orientation due to its anatomical position, originating from the anterior fossa of the tibial condyle and terminating at the lateral condyle of the femur, making knee varus highly susceptible to ACL injuries than the neutral and valgus positions [ 26 ] . The study by Orsi et al [ 27 ] confirmed the above assumption and found that ACL tearing due to knee varus was 46.6% higher than that due to valgus. Therefore, the present results suggest that patients with CAI who have experienced more than five ankle sprains should perform both ankle evertor strength training and proprioceptive exercises simultaneously to maintain a neutral ankle orientation during the landing phase and reduce knee compensatory responses. Simultaneously, it is important to strengthen muscles around the knee joint and core muscle groups to enhance the stability of the knee joint and minimize ACL load during exercise. This study found that CAIs with five ankle sprains had a significantly greater ankle inversion angular velocity during single-leg landing than CAI with only three or four ankle sprains. The reason for this was that the activation time of the ankle extensor muscles, such as the peroneus longus and peroneus brevis, was 126 ms later in CAI patients than the healthy population at the moment of initial contact. As a consequence, these patients were unable to promptly generate eversion moment, thereby inhibiting the immediate reduction of ankle inversion angular velocity [ 28 ] . The study found a positive correlation between the ankle inversion angular velocity and ACL loading. Previous studies have demonstrated that increased ankle inversion angular velocity leads to a reduction in postural stability in patients with CAI, as the vertical position of the center of mass moves away from the point of support [ 29 ] . Results from previous studies have shown that deficits in postural control have a high C-statistic of 0.94 for predicting ACL injuries [ 30 ] . Having said all of the above, during the rehabilitation process of CAI patients, it is important to not only improve the strength of the ankle eversion muscles, but also to focus on exercises that enhance body posture control. Implementing this approach could effectively mitigate knee joint compensation in patients with CAI, thus providing a preventive measure against the occurrence of ACL injuries [ 30 ] . This study found that CAI patients who had experienced more than five ankle sprains exhibited a larger vertical GRF during single-leg landing. This was because CAI patients developed a strategy to protect the ankle after multiple sprains, often completing the landing with a lower ankle dorsiflexion angle, which reduced the proportion of energy absorbed at the ankle. While this strategy might enhance ankle stability to some extent, it did not promote landing cushioning and tended to result in a higher vertical GRF [ 31 ] . Weinhandl et al [ 32 ] discovered a positive correlation between vertical GRF and ACL loading through forward kinetic modeling, which was consistent with the findings of this study. This was due to the fact that a higher vertical GRF increased the overall loading rate of the lower extremity and the load on the ACL [ 31 ] . The above results highlight the importance of enhancing ankle sagittal plane mobility in prevention of ACL injuries. In addition, because the hip extensors were stronger than the knee and ankle extensors, increasing the hip’s contribution to energy absorption might be beneficial in reducing knee compensation in CAI patients [ 33 ] . Serpell et al [ 34 ] demonstrated that the biceps femoris frequently contracts in conjunction with the vastus lateralis muscles, resulting in increased anterior-posterior tibial displacement and passive stretching of the ACL by approximately 0.52 mm. In addition, sustained contraction of the biceps femoris during exercise could cause muscle strain and contractile inhibition, leading to an imbalance of forces around the knee that may further aggravate ACL load [ 34 ] . The present study found that CAI patients with four ankle sprains demonstrated greater biceps femoris muscle strength during exercise, which positively correlated with ACL loading, consistent with previous research [ 34 ] . Increased biceps strength during landing in CAI patients might be due to the fact that ankle instability might affect sensorimotor control at the level of the spine, thus altering the feed-forward mechanisms of the lower extremity joints, and finally causing the biceps femoris to be activated prior to landing and increasing the load on the ACL. Serpell et al [ 34 ] conducted a study which concluded that intentional activation of both the biceps femoris and the vastus medialis could reduce anteroposterior displacement of the tibia and ACL elongation by 1.2 mm and 2.0 mm, respectively. Therefore, co-activation training of the biceps femoris and vastus medialis could play an important role in minimizing ACL injuries in CAI patients. This study found that CAI patients with more than 5 ankle sprains exhibited greater rectus femoris muscle force during the landing phase. This was attributed to the limited ankle dorsiflexion in CAI patients, which reduced the energy absorption capacity of the ankle joint. As a result, patients had to maintain higher knee extensor muscle force to absorb the residual GRF [ 35 ] . In accordance with the findings of Li et al [ 36 ] , the application of a force measuring 200 N to the rectus femoris muscle during knee extension yielded a pronounced increase in the anteroposterior displacement of the tibia, concomitant with an approximate 70 N augmentation in the load exerted on the ACL. Furthermore, co-contraction of the quadriceps and hamstrings further increased the ACL force, and if it exceeded 2020 N, a serious ACL injury might occur [ 36 ] . It was suggested that patients with CAI should first focus on improving the flexibility of the ankle joint in the sagittal plane, increasing the energy absorption capacity of the ankle joint during landing, and reducing the cushioning load on the rectus femoris muscle. The gastrocnemius and soleus muscles together form the triceps surae muscles, which are responsible for keeping the body upright and play a crucial role in maintaining the stability of the ankle and knee joints. A study utilizing a 2D geometric model discovered that activation of the gastrocnemius and soleus muscles resulted in a reduction of ACL strain at all knee flexion angles [ 37 ] . In a subsequent study, Ali et al [ 38 ] simulated a single-leg landing maneuver and found that full activation of the gastrocnemius muscle had a protective effect on the ACL. The present results indicate that CAI patients with more than five ankle sprains exhibited lower gastrocnemius and soleus muscle strength during single-leg landing, which increased the load on the ACL. The reason for this might be that the motor neuron pools of the gastrocnemius, soleus and quadriceps muscles are interconnected. Patients with CAI often experience increased rectus femoris muscle strength during exercise, which inhibits the activation of the gastrocnemius and soleus muscles. These biomechanical characteristics decrease the muscle’s ability to protect the ACL, resulting in a significant increase in ACL load [ 39 ] . This finding highlights the importance of improving ankle energy absorption and reducing rectus femoris muscle tension during exercise in patients with CAI. In summary, although the results of this study can help to understand the relationship between lower extremity movement patterns and ACL load in CAI patients with different numbers of ankle sprains, there are some limitations. For example, this study only explored participants who had experienced 2, 3, 4, 5 or 6 or more ankle sprains, and future studies could further subdivide the “6 or more” category so that the results of the study can be more targeted. 5 Conclusion Patients with CAI who have experienced more than four ankle sprains within a year exhibited knee compensation and increased ACL load during single-leg landing. Limited ankle dorsiflexion, increased ankle inversion angle, excessive vertical GRF, and insufficient gastrocnemius and soleus muscle strength might increase ACL load. Therefore, patients with more than four ankle sprains should focus on increasing ankle dorsiflexion, performing rehabilitation of the ankle evertor, plantar flexor, and knee extensor muscle groups, and consider adjusting the energy absorption patterns of the lower extremity joints to more effectively cushion GRF, and reduce ACL load. Declarations Ethical Approval: The study was performed in accordance with the ethical standards of the Declaration of Helsinki given ethics approval was obtained from the Ethics Committee of East China Normal University on 11 December 2023. Funding: The authors have not received a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors. Author Contribution Zeyi Zhang and Youping Sun was responsible for the conception and design of the study and data collection; Zeyi Zhang, Shengmeng Wei and Hanlin Shi were involved in the processing and statistical analysis of data; Zeyi Zhang were involved in the drafting of the manuscript; and all authors contributed to the interpretation of the data for the work and revising it critically for important intellectual content. All the authors finally approved the manuscript. Youping Sun was responsible for obtaining project funding and takes responsibility for the integrity of the work as a whole. All authors have read and agreed to the published version of the manuscript. Availability of data and materials: The datasets generated and/or analysed during the current study are not publicly available due the pending closure of the relevant research project but are available from the corresponding author on reasonable request. Patient involvement statement: Study participants were not involved in the design, conduct, interpretation, or translation of the current research. Data sharing statement: All data used in this study are available upon request. For requests of the raw data, please contact Zeyi Zhang ( [email protected] ). The raw data from this study can be used for review studies (e.g., meta-analyses). References HERZOG M M, KERR Z Y, MARSHALL S W, et al.Epidemiology of Ankle Sprains and Chronic Ankle Instability[J]. J Athl Train,2019,54(6):603-610. VAN RIJN R M, VAN OS A G, BERNSEN R M, et al.What is the clinical course of acute ankle sprains? A systematic literature review[J]. Am J Med,2008,121(4):324-331.e326. HERTEL J, CORBETT R O.An Updated Model of Chronic Ankle Instability[J]. J Athl Train,2019,54(6):572-588. MOISAN G, DESCARREAUX M, CANTIN V.Effects of chronic ankle instability on kinetics, kinematics and muscle activity during walking and running: A systematic review[J]. 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SERPELL B G, SCARVELL J M, PICKERING M R, et al.Medial and lateral hamstrings and quadriceps co-activation affects knee joint kinematics and ACL elongation: a pilot study[J]. BMC Musculoskelet Disord,2015,16:348. LI Y, KO J, WALKER M A, et al.Does chronic ankle instability influence lower extremity muscle activation of females during landing?[J]. J Electromyogr Kinesiol,2018,38:81-87. LI G, RUDY T W, SAKANE M, et al.The importance of quadriceps and hamstring muscle loading on knee kinematics and in-situ forces in the ACL[J]. J Biomech,1999,32(4):395-400. ADOUNI M, SHIRAZI-ADL A, MAROUANE H.Role of gastrocnemius activation in knee joint biomechanics: gastrocnemius acts as an ACL antagonist[J]. Comput Methods Biomech Biomed Engin,2016,19(4):376-385. ALI N, ANDERSEN M S, RASMUSSEN J, et al.The application of musculoskeletal modeling to investigate gender bias in non-contact ACL injury rate during single-leg landings[J]. Comput Methods Biomech Biomed Engin,2014,17(14):1602-1616. SEDORY E J, MCVEY E D, CROSS K M, et al.Arthrogenic muscle response of the quadriceps and hamstrings with chronic ankle instability[J]. J Athl Train,2007,42(3):355-360. Footnotes "Segments" is a body part that can move around a joint axis, such as the head, trunk, upper limbs, or lower limbs. It can also refer to a part of a limb, such as the hand, forearm, upper arm, foot, calf, or thigh. Additional Declarations No competing interests reported. Supplementary Files STROBEACLCAI.pdf Cite Share Download PDF Status: Published Journal Publication published 04 Apr, 2025 Read the published version in Journal of NeuroEngineering and Rehabilitation → Version 1 posted Editorial decision: Revision requested 25 Aug, 2024 Reviews received at journal 08 Jul, 2024 Reviews received at journal 04 Jul, 2024 Reviewers agreed at journal 02 Jul, 2024 Reviews received at journal 01 Jul, 2024 Reviewers agreed at journal 28 Jun, 2024 Reviewers agreed at journal 28 Jun, 2024 Reviewers agreed at journal 27 Jun, 2024 Reviews received at journal 27 Jun, 2024 Reviewers agreed at journal 27 Jun, 2024 Reviewers agreed at journal 26 Jun, 2024 Reviewers invited by journal 26 Jun, 2024 Editor assigned by journal 20 May, 2024 Submission checks completed at journal 20 May, 2024 First submitted to journal 14 May, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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diagram.\u003c/p\u003e","description":"","filename":"Fig.1.png","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/65e8e992b0857b841f215e85.png"},{"id":57865249,"identity":"c145beb7-f8ac-48ab-9e0d-fe8a70acac97","added_by":"auto","created_at":"2024-06-06 15:38:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":328773,"visible":true,"origin":"","legend":"\u003cp\u003eStatic calibration and single-leg landing movement.\u003c/p\u003e","description":"","filename":"Fig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/73001ff74e62371db4efa8ab.png"},{"id":57865246,"identity":"705ce71e-4213-4aef-ae2c-42ac2ece30e7","added_by":"auto","created_at":"2024-06-06 15:38:09","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":121513,"visible":true,"origin":"","legend":"\u003cp\u003eLocation of ACL insertion in the OpenSim model, indicated by a dashed circle.\u003c/p\u003e","description":"","filename":"Fig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/c05fa03c059bd64c3e45bfa6.png"},{"id":57865247,"identity":"ce495fd3-266b-4188-909c-0d47648055d4","added_by":"auto","created_at":"2024-06-06 15:38:09","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":263121,"visible":true,"origin":"","legend":"\u003cp\u003eACL load curve and peak characteristics of CAI patients during single-leg landing.\u003c/p\u003e\n\u003cp\u003eNote: within the figure, the solid line delineates the mean curve of the indicator, whereas the shaded portion depicts the standard deviation.\u003c/p\u003e","description":"","filename":"Fig.4.png","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/b854096104d62664b502ba26.png"},{"id":57865254,"identity":"936a736b-543e-437f-91ee-2815681fb0b8","added_by":"auto","created_at":"2024-06-06 15:38:10","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":225242,"visible":true,"origin":"","legend":"\u003cp\u003eJoint angle of CAI patients during single-leg landing.\u003c/p\u003e\n\u003cp\u003eNote: in the figure above, the symbol '*' signifies statistically significant differences between factors, with a p-value less than 0.05. Moreover, '**' denotes highly significant differences between factors, with a p-value less than 0.01, the same applies subsequently.\u003c/p\u003e","description":"","filename":"Fig.5.png","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/3816cec36d2e87c6257d3524.png"},{"id":57865252,"identity":"c870bc59-f714-4408-8e16-eb83b37a5ea6","added_by":"auto","created_at":"2024-06-06 15:38:09","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":102041,"visible":true,"origin":"","legend":"\u003cp\u003eJoint angular velocity of CAI patients during single-leg landing.\u003c/p\u003e","description":"","filename":"Fig.6.png","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/0a2704b9f72b5f3b1a4ee51b.png"},{"id":57865251,"identity":"ad56c7f2-1b28-4216-9447-84928143c337","added_by":"auto","created_at":"2024-06-06 15:38:09","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":170562,"visible":true,"origin":"","legend":"\u003cp\u003eGRF characteristics of CAI patients during single-leg landing.\u003c/p\u003e","description":"","filename":"Fig.7.png","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/e36b505d21da8d2180023fcc.png"},{"id":57865850,"identity":"972847bf-b724-4365-b9a2-0462e188f8da","added_by":"auto","created_at":"2024-06-06 15:46:09","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":504257,"visible":true,"origin":"","legend":"\u003cp\u003eMuscle strength of CAI patients during single-leg landing.\u003c/p\u003e","description":"","filename":"Fig.8.png","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/52580cdce7d3e300b07b108d.png"},{"id":80082278,"identity":"eb82cfc6-afa6-459c-868f-290ec73a6e58","added_by":"auto","created_at":"2025-04-07 16:08:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3657966,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/56cdddea-a27e-4ba2-9b44-e59f4b17b4be.pdf"},{"id":57865849,"identity":"8546bfab-6576-4372-8fdf-d39738d19d95","added_by":"auto","created_at":"2024-06-06 15:46:09","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":162893,"visible":true,"origin":"","legend":"","description":"","filename":"STROBEACLCAI.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4419864/v1/83fbefb35493d173d2c8ffff.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Association between Lower Extremity Movement Patterns and ACL Loading in CAI Patients Across Varied Ankle Sprain Frequencies within a Year","fulltext":[{"header":"Key points","content":"\u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eFindings\u003c/b\u003e \u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e\u003cp\u003ePatients with CAI who have experienced more than four ankle sprains within a year exhibited severe knee compensation and increased ACL load during single-leg landing.\u003c/p\u003e\u003cp\u003eLimited ankle dorsiflexion, increased ankle inversion angle, excessive vertical GRF, and insufficient gastrocnemius and soleus muscle strength might increase ACL load in patients with CAI who have experienced more than four ankle sprains within a year.\u003c/p\u003e\u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eImplications\u003c/b\u003e \u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e\u003cp\u003eIndividuals with a history of more than four ankle sprains should undergo a thorough examination of knee health and receive regular monitoring to prevent the development of ACL injuries.\u003c/p\u003e\u003cp\u003ePatients with more than four ankle sprains within a year should focus on increasing ankle dorsiflexion, performing rehabilitation of the ankle evertor, plantar flexor, and hamstring, and consider adjusting the energy absorption patterns of the lower extremity joints to more effectively cushion GRF.\u003c/p\u003e\u003cul\u003e \u003cli\u003e \u003cp\u003e \u003cb\u003eCaution\u003c/b\u003e \u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e\u003cp\u003eThis study only explored participants who had experienced 2, 3, 4, 5 or 6 or more ankle sprains, and future studies could further subdivide the “6 or more” category so that the results of the study can be more targeted.\u003c/p\u003e"},{"header":"1 Introduction","content":"\u003cp\u003eAnkle sprains are a prevalent type of lower extremity injury, with 11.88% of cases occurring during sports activities\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e. Regrettably, without proper rehabilitation, around 73% of patients developed chronic ankle instability (CAI) \u003csup\u003e[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/sup\u003e. CAI is characterized by lateral ankle ligament laxity, pain, swelling and ankle dysfunction. An ankle sprain increases the likelihood of recurrent ankle sprains\u003csup\u003e[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]\u003c/sup\u003e A systematic review found that 68\u0026thinsp;~\u0026thinsp;78% of CAI patients experience recurring ankle sprains due to impaired balance and neuromuscular control of the affected lower extremity during exercise, which significantly reduces the quality of life and participation in sports\u003csup\u003e[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eProlonged repetitive ankle sprains can damage mechanical receptors in the joint capsule\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. This can disrupt electrical conduction between the mechanoreceptors and the central nervous system, leading to a significant reduction in ankle position and motion perception, which impairs control of the joint and the ability to cushion foot landings\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. Moreover, it might trigger proximal adaptive responses that increase the risk of knee injuries, particularly anterior cruciate ligament (ACL) injuries\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. Research has shown that between 52% and 60% of patients with ACL injuries report symptoms related to CAI\u003csup\u003e[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]\u003c/sup\u003e. In a 6-month health survey of 146 female footballers, Soderman and colleagues found that 60% of ACL-injured players suffered recurrent ankle sprain\u003csup\u003e[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eTherefore, a number of studies have attempted to investigate the biomechanical mechanisms that make patients with CAI more susceptible to ACL injury. These studies, both domestically and internationally, have typically used OpenSim modeling software to calculate dynamic ACL loads, which is a widely utilized and accurate method\u003csup\u003e[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/sup\u003e. Delahunt et al\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e found that patients with CAI experienced significantly limited ankle dorsiflexion during the landing phase compared to healthy subjects. Furthermore, knee flexion angle was significantly reduced during initial contact\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. These biomechanical changes might increase the angle between the patellar tendon and the tibial shaft, leading to greater anterior tibial shear forces, which increase susceptibility to ACL injuries\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. However, other research investigated the movement strategies of lower extremities during single-leg landing in patients with CAI and found that they often exhibit larger ankle dorsiflexion angle, knee flexion angle, and hip flexion angle than do healthy individuals and Copers\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/sup\u003e. Simpson et al\u003csup\u003e[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]\u003c/sup\u003e. conducted a systematic study and found that patients with CAI exhibited prolonged activation latency of the peroneus longus and piriformis muscles during the landing phase. This reduced the cushioning effect of the ankle against the medial-lateral ground reaction force (GRF), which in turn led to an increase in knee loading and thus higher ACL loads\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e. However, a study that analyzed the forces and energy dissipation in the lower extremity of CAI patients during vertical jump landing. The findings elucidated a noteworthy revelation: the knee joint experienced lower loads compared to other joints in individuals with CAI\u003csup\u003e[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. As indicated by these varied reports, the biomechanical mechanism that made CAI patients more susceptible to ACL injuries is not well understood. This might be due, in part, to the fact that none of the studies mentioned above took into account the ankle sprain frequency of CAI patients\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]\u003c/sup\u003e. Previous research has shown that the number of self-reported previous sprains was associated with ankle dysfunction and instability, particularly in individuals with two or more prior ankle sprains, who exhibit reduced ankle function and stability compared to the single ankle sprain group\u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e. Additionally, the number of previous ankle sprains in CAI patients was positively correlated with the severity of ACL injuries, with a χ\u003csup\u003e2\u003c/sup\u003e value of up to 5.27\u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe objective of this study was to compare lower extremity biomechanics in CAI patients across different ankle sprain frequencies within a year. Additionally, the relationship between these biomechanical characteristics and ACL strain was analyzed. The present study hypothesizes that patients with CAI who have experienced more frequent ankle sprains might experience increased ACL loading. Additionally, this population exhibited insufficient ankle dorsiflexion angle, gastrocnemius muscle force, soleus muscle force, and greater ankle inversion angle, inversion angle velocities during single-leg landing, which might result in an increase in ACL loading. The results of this study may help to identify the threshold at which CAI patients begin to experience knee compensation, and provide a scientific reference for future studies to evaluate potential associations between ankle sprain and ACL injury.\u003c/p\u003e"},{"header":"2 Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1 Study design\u003c/h2\u003e \u003cp\u003eThis study monitored the ankle sprains frequency within a year among individuals with CAI, categorizing them into groups with 2, 3, 4, 5, and 6 or more occurrences of ankle sprains. Biomechanical tests were conducted to analyze the reasons for knee joint compensation among CAI patients with different ankle sprains frequencies within a year. This research was conducted at the Key Laboratory of Adolescent Health Assessment and Exercise Intervention of Ministry of Education, East China Normal University, April 2023.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2 Participants\u003c/h2\u003e \u003cp\u003eThe study participants were chosen according to the International Ankle Consortium\u0026rsquo;s criteria for identifying patients with CAI\u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e. Participants were included in the study if they satisfied the following criteria: 1) Participants were required to have experienced at least one ankle sprain that resulted in \u0026ge;\u0026thinsp;1-day interruption of physical activity and was associated with inflammatory symptoms (e.g., pain, swelling). Furthermore, participants must have suffered an initial ankle sprain at least 12 months previously, the most recent of which having occurred at least 3 months before the experiment; 2) On at least two occasions, participants must have experienced their ankle \u0026ldquo;giving way\u0026rdquo; due to repeated (two or more) ankle sprains of the affected ankle within the six months prior to the experiment, and each individual\u0026rsquo;s Cumberland Ankle Instability Scale (CAIT) score must have been less than 24; and 3) their Foot and Ankle Ability Measure (FAAM)-Activities of Daily Living (ADL) scale score had to be less than 90%, and their FAAM-Sport scale score had to be less than 80%. Additionally, their Foot and Ankle Outcome Score (FAOS) score had to be less than 75% in three or more categories. Exclusion criteria for participation in the experiment included the following: 1) Participants had a history of previous surgeries to the musculoskeletal structures (ie, bones, joint structures and nerves) in either lower extremity; 2) Participants had a history of lower extremity fracture; and 3) Within 3 months prior to the experiment, participants had an acute injury to the joint structures of the lower extremity that compromised the integrity and function of the joints and resulted in cessation of physical activity for at least 1 day.\u003c/p\u003e \u003cp\u003eIn this investigation, 80 CAI patients were enlisted into the study one year antecedent to the formal biomechanical assessments. Throughout this interim, any instances of ankle sprains encountered during participants' routine activities were expeditiously relayed to the testers through the WeChat platform (Tencent, China). The testers meticulously documented the frequency of ankle sprains experienced by each participant within the one-year interval. Subsequently, participants were stratified into groups based on the frequency of ankle sprains occurring within the specified time frame, categorized as 2, 3, 4, 5, or greater than 6 instances of injury history. However, one participant was excluded due to a history of lower extremity fractures, while five others were unable to participate in the formal experiment for personal reasons, resulting in a final participation count of 74 individuals (Fig.\u0026nbsp;1). All participants carefully read the protocol of this experiment, understood the experimental procedure and signed the informed consent form. Basic anthropometric tests, including gender, age, height, weight, CAIT score, FAAM-ADL score, FAAM-Sport score and FAOS score were performed on the subjects prior to the formal experiment, and the results are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographics of participants (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of ankle sprains/(times)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e6 or more\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSample size/(n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003egender\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003emale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003emale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003emale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003emale\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge/(year)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e22.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e20.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e21.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHeight/(cm)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e175.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e176.9\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e177.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e176.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e175.9\u0026thinsp;\u0026plusmn;\u0026thinsp;7 .0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWeight/(kg)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e71.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e71.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e70.9\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e73.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e75.8\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eCAIT score\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e17.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e17.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFAAM-ADL score/(%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e81.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e82.0\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e77.9\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e78.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e79.9\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFAAM-Sport score/(%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69.0\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e70.1\u0026thinsp;\u0026plusmn;\u0026thinsp;6.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e68.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e68.9\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e67.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eFAOS score/(%)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSymptom/(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e68.1\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e66.9\u0026thinsp;\u0026plusmn;\u0026thinsp;7.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e67.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e66.2\u0026thinsp;\u0026plusmn;\u0026thinsp;5.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePain/(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e72.6\u0026thinsp;\u0026plusmn;\u0026thinsp;9.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e72.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e71.2\u0026thinsp;\u0026plusmn;\u0026thinsp;11.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e68.7\u0026thinsp;\u0026plusmn;\u0026thinsp;10.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e69.3\u0026thinsp;\u0026plusmn;\u0026thinsp;9.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eActivities of Daily Living/(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e81.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e78.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e79.7\u0026thinsp;\u0026plusmn;\u0026thinsp;5.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e78.9\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSport/(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e70.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e68.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e66.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e68.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eQuality of Life/(%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e70.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e73.2\u0026thinsp;\u0026plusmn;\u0026thinsp;6.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e66.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e68.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e65.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3 Test Apparatus\u003c/h2\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1 Motion capture system\u003c/h2\u003e \u003cp\u003eIn this study, 12 Vero v2.2 infrared cameras (Vicon, USA) and a motion capture system with a 14 mm infrared marker ball were used to record single-leg landing maneuvers. The cameras were positioned at a height of 2.5 m and used a sampling frequency of 100 Hz.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2 Three-dimensional force plate\u003c/h2\u003e \u003cp\u003eIn this study, two 40 cm \u0026times; 60 cm Kistler 3D force plates (Kistler Inc., Switzerland) were used to record the GRF of the subjects during single-leg landing with a sampling frequency of 1 kHz.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.3.3 Surface EMG testing system\u003c/h2\u003e \u003cp\u003eThe surface electromyography (EMG) device used in this paper was the Telemyo 2400DTS sEMG wireless telemetry system (Noraxon, USA) that contained a 32-channel signal collector, a USB data transfer interface and a wireless receiver card that either could be connected wirelessly or via a cable to a computer. For surface EMG testing, it was often used in conjunction with electrodes and pre-amplifiers.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003e2.4 Experimental Design and Testing Procedures\u003c/h2\u003e \u003cp\u003eBefore the formal experiment, to ensure optimal adhesion of electromyography electrodes, the designated areas underwent meticulous hair removal. Additionally, participants were provided with uniform shorts, vests and sports shoes, and performed uniform warm-up movements, including jogging, deep squatting, lunging, longitudinal jumping, direction-change running, etc. The warm-up time was 10 minutes. Afterward, testers provided a detailed explanation of the essentials of the test movements to the subjects, and sufficient time was allowed for practice. After the preparatory work was completed, the reflective marker ball and the electrodes were uniformly attached to the participants, and static calibration data were collected. The static calibration movements are shown in Fig.\u0026nbsp;2. Markers were attached to 39 bony marker points, including the left anterior head, right anterior head, 7th cervical vertebra, 10th lumbar vertebra, left anterior superior iliac spine, right anterior superior iliac spine, left posterior superior iliac spine, right posterior superior iliac spine, knees, thighs, calves, ankle joints, toes, heels, etc. The electrodes were attached to 8 lower limb muscles including the biceps femoris, rectus femoris, vastus lateralis, vastus medialis, gastrocnemius, soleus, peroneus longus and tibialis anterior in accordance with Surface Electromyography for the Non-Invasive Assessment of Muscle (SENIAM) guidelines\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e. At the start of the formal test, CAI patients were asked to stand on a 40 cm high test platform with the affected leg and hands naturally falling to either side. After the infrared camera started recording, participants dropped onto the force platform with a single leg, subsequently maintaining body equilibrium for a minimum of three seconds post-grounding\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. Instances of secondary movement post-grounding resulting in an inability to sustain balance were excluded from data analysis. (Fig.\u0026nbsp;2). They rested for one minute and repeated the same maneuver four times, resulting in a total of five valid data sets.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e2.5 Data Extraction and Preparation\u003c/h2\u003e \u003cp\u003eThis section describes analyses of the biomechanical data from the moment of landing, when the force value on the platform exceeded 10 N, to the moment of maximum knee flexion. Data from the marked points and the GRF data were collected and processed using Vicon software (Vicon Industries, Inc., USA). The original data were smoothed using a fourth order Butterworth filter with cut-off frequencies of 10 Hz and 100 Hz for the marker and GRF data, respectively. The midpoint of the line connecting the medial and lateral femoral condyle markers was defined as the center of the knee joint, and the midpoint of the line connecting the medial and lateral ankle markers was defined as the center of the ankle joint\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e. EMG signal data were processed using Matlab 2016b software, including applying a Butterworth band-pass filter with frequencies ranging from 10 Hz to 400 Hz, full-wave rectification, and low-pass filtering with a cut-off frequency of 6 Hz\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe kinematic and kinetic data were exported to a c3d format file, converted to mot (Multiple Object Tracking) and trc (Track Row Column) formats using the c3dExport.m package in Matlab 2016b, and then imported into OpenSim 4.1. In this study, the Gait_2354 model in OpenSim was used and the ACL was added to this model. The ACL model extended from the anterior fossa of the tibial condyle to the lateral condyle of the femur, and represented a passive nonlinear elastic soft tissue along the direction of the ligament starting and ending points. The ACL was set up as a passive tissue, with activation of contractile elements being inhibited (Fig.\u0026nbsp;3).\u003c/p\u003e \u003cp\u003eIn OpenSim, we first constructed a generic model based on the subject\u0026rsquo;s height, weight and muscle data, and then scaled the length and mass of the segments\u003csup\u003e1\u003c/sup\u003e using the marker point data obtained from the experiment (Scaling Model, SM). Furthermore, we verified the optimality of the model by finding the best-fit model for the data through inverse kinematics. The process primarily utilized the weighted least squares method to compute the disparities between the experimentally measured 3D coordinates of the marker points, the coordinate system, and the model coordinates, and to minimize these disparities. Force residuals (\u003cem\u003eFresidual\u003c/em\u003e) represented discrepancies between the experimental mechanical data and the simulation results. The Reduce Residuals Algorithm in OpenSim could reduce the residuals by optimizing the trajectory and making adjustments to the coupling quality and other variables. The maximum permissible force error was generally between 0 and 10 N, and the maximum permissible torque error was between 0 and 50 N. In addition, Calculate Muscle Control was used to simulate lower extremity muscle force and ACL load. Finally, the kinematic, kinetic and muscle activation data from OpenSim simulations were compared with experimental data in this study using the validation method proposed by Błażkiewicz et al\u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]\u003c/sup\u003e. OpenSim simulations were considered accurate if differences between residual pelvic forces and peak residual moments derived from OpenSim simulations and experimental measurements did not exceed 20 N and 75 N\u0026sdot;m, respectively, and EMG curves were similar.\u003c/p\u003e \u003cp\u003e \u003cb\u003e2.6 Experimental Indicators\u003c/b\u003e \u003c/p\u003e \u003cp\u003e1) ACL load was defined as the force on the ACL during human movement. It was derived from OpenSim modeling and normalized to a multiple of body weight (BW). 2) Joint angle was defined as the angle between adjacent hinges. Knee angle was defined as the angle between the thigh hinge and calf hinge, and ankle angle was defined as the angle between the calf hinge and the foot hinge. 3) Joint angular velocity is the angular displacement of the hinge around the joint\u0026rsquo;s center per unit of time and was usually derived from differentiation of angular displacement and time. 4) GRF is the force generated when the human body strikes the ground and was directly measured by the three-dimensional force plates. As GRF was strongly influenced by body weight, it was normalized by body weight. 5) Muscle force was defined as the force generated by muscle contraction during lower extremity movement and was derived from OpenSim modeling. As lower extremity muscle force during single-leg landing might be affected by body weight, muscle force was also normalized by body weight.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e2.7 Statistical Analysis\u003c/h2\u003e \u003cp\u003eThe study expressed all index data as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) and used an independently designed one-way ANOVA to compare differences in lower extremity joint kinematics, kinetics, muscle strength, and ACL loading between CAI patients who experienced 2, 3, 4, 5, and 6 or more ankle sprains, with the significance level set at \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05. The effect size of the one-way ANOVA, η\u003csup\u003e2\u003c/sup\u003e, was calculated. A low effect size was indicated by 0.01\u0026thinsp;≦\u0026thinsp;η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.06, a medium effect size by 0.06\u0026thinsp;≦\u0026thinsp;η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.14, and a high effect size by η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;≧\u0026thinsp;0.14\u003csup\u003e[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]\u003c/sup\u003e. Pearson\u0026rsquo;s correlation analysis was used to further investigate the relationship between lower extremity kinematics, kinetics, muscle strength and ACL loading in CAI patients. The correlation coefficient |r| \u0026ge; 0.50 was considered high, 0.50 \u0026gt; |r| \u0026ge; 0.30 was moderate, and 0.30 \u0026gt; |r| \u0026ge; 0.10 was low.\u003c/p\u003e \u003c/div\u003e"},{"header":"3 Results","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003e3.1 ACL Loading\u003c/h2\u003e \u003cp\u003eFigure 4 shows that CAI patients with 4 ankle sprains (4 sprains vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;4.812, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.218; 4 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;4.812, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.218), 5 sprains (5 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;4.812, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.218; 5 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;4.812, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.012, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.218), or 6 or more sprains (6 vs. 2 : F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;4.812, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.218; 6 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;4.812, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.218) had a significantly greater peak ACL load during single-leg landing than CAI patients with only 2 or 3 ankle sprains.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.2 Kinetics, Kinematics and Muscle Force of the Lower Extremity\u003c/h2\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;5, patients with CAI who suffered 4 sprains (4 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.394, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.270; 4 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.394, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.270), 5 sprains (5 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.394, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.270; 5 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.394, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.270), or 6 or more sprains (6 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.394, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.015, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.270; 6 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.394, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.012, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.270) exhibited a significantly lower ankle dorsiflexion angle during single-leg landings than those who suffered only 2 or 3 ankle sprains. Furthermore, CAI patients with 5 ankle sprains exhibited a significantly greater ankle inversion angle during single-leg landing than those with only 3 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.741, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.045, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.178) or 4 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.741, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.039, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.178). The ankle inversion angle during single-leg landing was significantly greater in patients with CAI who had experienced 6 or more ankle sprains than those who had only experienced 2 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.741, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.010, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.178), 3 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.741, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.178), or 4 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.741, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.178) sprains. Additionally, patients who had experienced 5 ankle sprains also had a significantly greater ankle inversion angle than those who only experienced 2 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.741, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.010, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.178), 3 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.741, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.178) or 4 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.741, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.178) sprains. Furthermore, the study found that CAI patients who experienced 5 sprains (5 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;5.230, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.233; 5 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;5.230, \u003cem\u003eP\u003c/em\u003e\u0026lt;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.233; 5 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;5.230, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.006, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.233) or more than 6 (6 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;5.230, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.030, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.233; 6 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;5.230, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.233; 6 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;5.230, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.233) had a significantly greater knee inversion angle during single-leg landing than those who experienced only 2, 3, or 4 ankle sprains.\u003c/p\u003e \u003cp\u003eFigure 6 shows that CAI patients with 5 ankle sprains had a significantly greater ankle inversion angular velocity during single-leg landing than those with only 3 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.624, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.025, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.086) or 4 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;1.624, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.050, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.086) sprains.\u003c/p\u003e \u003cp\u003eVertical GRF was greater in CAI patients with 5 (5 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.309, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.268; 5 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.309, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.268; 5 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.309, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.268) or more than 6 sprains (6 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.309, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.268; 6 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.309, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.018, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.268; 6 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.309, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.015, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.268) than CAI patients with only 2, 3, or 4 sprains (Fig.\u0026nbsp;7).\u003c/p\u003e \u003cp\u003eFigure 8 shows that CAI patients with 4 ankle sprains had greater strength in the long head of the biceps femoris muscle than those with 2 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;2.455, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.016, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.125), 3 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;2.455, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.030, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.125), 5 (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;2.455, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.010, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.125), or 6 or more (F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;2.455, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.017, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.125) sprains. Additionally, CAI patients with 5 (5 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.199, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.264; 5 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.199, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.264; 5 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.199, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.264) or 6 or more (6 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.199, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.264; 6 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.199, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.264; 6 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;6.199, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.264) ankle sprains had significantly greater rectus femoris muscle strength during single-leg landing than those with only 2 or 3 sprains. Furthermore, CAI patients who experienced 5 (5 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.644, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.030, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.174; 5 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.644, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.174; 5 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.644, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.019, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.174) or 6 or more (6 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.644, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.035, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.174; 6 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.644, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.174; 6 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;3.644, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.023, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.174) sprains exhibited reduced gastrocnemius muscle strength during single-leg landings than those who had only 2 to 4 ankle sprains. Additionally, those with 5 (5 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;8.146, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.321; 5 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;8.146, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.321; 5 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;8.146, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.321) or 6 (6 vs. 2: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;8.146, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.321; 6 vs. 3: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;8.146, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.321; 6 vs. 4: F\u003csub\u003e[1,72]\u003c/sub\u003e\u0026thinsp;=\u0026thinsp;8.146, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001, η\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.321) sprains exhibited significantly lower soleus muscle force during single-leg landing than those with only 2\u0026ndash;4 ankle sprains.\u003c/p\u003e \u003cp\u003eThe study found significant positive correlations between force produced by the long head of the biceps femoris muscle (r\u0026thinsp;=\u0026thinsp;0.532, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.041) during single-leg landing and ACL load in patients with CAI who had experienced 4 ankle sprains. Additionally, the dorsiflexion angle of the ankle was significantly negatively correlated with ACL load (r\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.707, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003). In CAI patients with five ankle sprains, ankle inversion angle (r\u0026thinsp;=\u0026thinsp;0.750, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001), ankle inversion velocity (r\u0026thinsp;=\u0026thinsp;0.538, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.039), and vertical GRF (r\u0026thinsp;=\u0026thinsp;0.761, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) during single-leg landing were significantly positively correlated with ACL load. Conversely, ankle dorsiflexion angle (r\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.765, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001), gastrocnemius muscle force (r\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.565, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.028), and soleus muscle force (r\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.762, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.001) were negatively correlated with ACL loading. In patients with CAI who experienced more than 6 ankle sprains, ankle inversion angle (r\u0026thinsp;=\u0026thinsp;0.808, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), knee varus angle (r\u0026thinsp;=\u0026thinsp;0.720, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004), vertical GRF (r\u0026thinsp;=\u0026thinsp;0.550, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.041), and rectus femoris muscle strength (r\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.863, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) were positively correlated with ACL load, whereas ankle dorsiflexion angle (r\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.640, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014) and soleus muscle force (r\u0026thinsp;=\u0026thinsp;\u0026minus;\u0026thinsp;0.763, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002) was negatively correlated with ACL load (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCorrelation of lower extremity kinematics, kinetics, and muscle strength with ACL load in patients with CAI\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"16\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c11\" colnum=\"11\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c12\" colnum=\"12\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c13\" colnum=\"13\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c14\" colnum=\"14\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c15\" colnum=\"15\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c16\" colnum=\"16\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eIndex\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"14\" nameend=\"c15\" namest=\"c2\"\u003e \u003cp\u003eACL loading\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e2 sprains\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003e3 sprains\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c9\" namest=\"c8\"\u003e \u003cp\u003e4 sprains\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003e5 sprains\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c16\" namest=\"c14\"\u003e \u003cp\u003e6 or more sprains\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003er\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003er\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003er\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003er\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c14\"\u003e \u003cp\u003er\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c15\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle dorsiflexion angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;0.024\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.934\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.077\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.786\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026minus;0.707\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.765\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.640\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle inversion angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.262\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.346\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.072\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.798\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026minus;0.009\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.974\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.750\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.808\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle internal rotation angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.010\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.972\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.174\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.536\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.197\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.482\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.982\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.715\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee flexion angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.005\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.987\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.196\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.484\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.378\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.165\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.265\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.340\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.184\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.530\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee varus angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;0.591\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.020\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.341\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.214\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026minus;0.279\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.313\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.418\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.121\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.720\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee internal rotation angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.363\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.184\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.268\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.334\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.026\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.928\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.343\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.211\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.981\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle plantarflexion angular velocity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.026\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.927\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.094\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.739\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.124\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.659\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.446\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.095\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.441\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.114\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle inversion angular velocity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.593\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.020\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.472\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.076\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.534\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.040\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.538\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.039\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.144\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.623\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle internal rotation angular velocity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;0.057\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.840\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.149\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.596\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.338\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.217\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.022\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.937\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.335\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.241\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee flexion angular velocity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.375\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.168\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.316\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.251\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.109\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.698\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.019\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.947\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.025\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.931\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee inversion angular velocity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.379\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.164\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.652\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.008\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.260\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.349\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.655\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.008\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.279\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee internal rotation angular velocity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.059\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.835\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.442\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.099\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.260\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.495\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.061\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.560\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.037\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnterior-posterior GRF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.423\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.116\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.732\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.665\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.060\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.832\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.411\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.144\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMedial-lateral GRF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;0.544\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.036\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.582\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.023\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026minus;0.380\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.163\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.816\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.725\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVertical GRF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.605\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.017\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.251\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.367\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.205\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.464\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.761\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.550\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLong head of biceps femoris strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;0.406\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.133\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.305\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.270\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.532\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.416\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.123\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.163\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.578\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eShort head of biceps femoris strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.498\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.059\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.178\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.526\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.950\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.123\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.663\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.432\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.123\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003esartorius muscle strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.867\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.313\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.255\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.622\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.337\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.219\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.173\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.555\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGracilis muscle strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.417\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.122\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.234\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.400\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026minus;0.094\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.740\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.119\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.672\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.059\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.841\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003erectus femoris muscle strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.715\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.423\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.116\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.189\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.501\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.042\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.882\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e0.863\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003egastrocnemius muscle strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;0.041\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.883\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.007\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.979\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.042\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.881\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.565\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.028\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.763\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSoleus muscle strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.505\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.055\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.056\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.842\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.273\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.325\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.762\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.377\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.184\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTibialis posterior muscle strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.206\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.464\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.165\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.556\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026minus;0.070\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.804\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.092\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.746\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.992\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTibialis anterior muscle strength\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e\u0026minus;0.017\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.952\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.316\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.251\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e\u0026minus;0.346\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.207\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e\u0026minus;0.478\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.072\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c14\"\u003e \u003cp\u003e\u0026minus;0.032\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c15\"\u003e \u003cp\u003e0.914\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c16\" namest=\"c16\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"4 Discussion","content":"\u003cp\u003eThe study results indicate that CAI patients who have experienced more than four ankle sprains exhibited increased ACL loading during single-leg landing. This finding supported the study\u0026rsquo;s hypothesis, which suggested that knee joint compensation in CAI patients primarily occurred after four ankle sprains.\u003c/p\u003e \u003cp\u003eThis paper reported that ankle dorsiflexion was limited during the landing phase in patients with CAI who had more than four ankle sprains. This might be due to excessive tension in the non-contractile tissues or degenerative lesions of the ankle joint caused by multiple sprains, which might reduce the flexibility of the anterior-posterior sliding of the talus and affect the brain\u0026rsquo;s ability to perceive the distance between the talus and the malleolus\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. These alterations ultimately result in reduced ankle dorsiflexion\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. The study results revealed that decreased ankle dorsiflexion angle leads to a substantial increase in ACL load in CAI patients. Previous research had demonstrated that reduced ankle dorsiflexion angle during landing reduced the proportion of energy absorbed and dissipated in the ankle joint. As a result, the remaining GRF was transferred to the knee joint, leading to knee joint energy compensation\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. Meanwhile, based on the sagittal plane coupling theory of lower extremity joints, limited ankle dorsiflexion angle often accompanies reduced knee flexion displacement during landing\u003csup\u003e[\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e. These biomechanical changes might increase the angle between the patellar tendon and the tibial shaft, causing the knee to bear greater anterior tibial shear force and increasing ACL loading\u003csup\u003e[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e. Hagins et al\u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e conducted a study that confirmed the aforementioned theory. They discovered that limited ankle dorsiflexion significantly increased knee valgus displacement. These biomechanical changes increased ACL load. Therefore, it is recommended that dorsiflexion stretching exercises, plantarflexor relaxation training, or dorsiflexor strength training should be used to increase ankle dorsiflexion and reduce knee compensation during landing in CAI patients with more than four ankle sprains\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/sup\u003e. It has been reported that a single session of ankle release therapy could also significantly improve the neuronal excitability of the soleus muscle and the static postural control of the lower extremity. Therefore, therapy can significantly improve ankle function in patients with CAI\u003csup\u003e[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn addition, the study revealed that CAI patients with more than 5 ankle injuries had a greater ankle inversion angle during single-leg landing, which might be due to joint kinematics and positioning deficits that made it difficult for them to accurately return the ankle to a neutral orientation, resulting in landing with an inverted posture\u003csup\u003e[\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/sup\u003e. The meta-analysis showed that CAI patients had moderate or mild eversion muscle weakness at centripetal contraction velocities between 30\u0026deg;/s and 120\u0026deg;/s. This weakness might be a significant contributing factor to the increased ankle inversion angle, which in turn further contributed to the increased knee inversion angle due to the presence of kinematic chains in the joints of the lower extremity. The above kinematic characteristics were significantly correlated with ACL loading. The reason for this was that the ACL was pre-strained in the inverted orientation due to its anatomical position, originating from the anterior fossa of the tibial condyle and terminating at the lateral condyle of the femur, making knee varus highly susceptible to ACL injuries than the neutral and valgus positions\u003csup\u003e[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/sup\u003e. The study by Orsi et al\u003csup\u003e[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/sup\u003e confirmed the above assumption and found that ACL tearing due to knee varus was 46.6% higher than that due to valgus. Therefore, the present results suggest that patients with CAI who have experienced more than five ankle sprains should perform both ankle evertor strength training and proprioceptive exercises simultaneously to maintain a neutral ankle orientation during the landing phase and reduce knee compensatory responses. Simultaneously, it is important to strengthen muscles around the knee joint and core muscle groups to enhance the stability of the knee joint and minimize ACL load during exercise.\u003c/p\u003e \u003cp\u003eThis study found that CAIs with five ankle sprains had a significantly greater ankle inversion angular velocity during single-leg landing than CAI with only three or four ankle sprains. The reason for this was that the activation time of the ankle extensor muscles, such as the peroneus longus and peroneus brevis, was 126 ms later in CAI patients than the healthy population at the moment of initial contact. As a consequence, these patients were unable to promptly generate eversion moment, thereby inhibiting the immediate reduction of ankle inversion angular velocity\u003csup\u003e[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/sup\u003e. The study found a positive correlation between the ankle inversion angular velocity and ACL loading. Previous studies have demonstrated that increased ankle inversion angular velocity leads to a reduction in postural stability in patients with CAI, as the vertical position of the center of mass moves away from the point of support\u003csup\u003e[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/sup\u003e. Results from previous studies have shown that deficits in postural control have a high C-statistic of 0.94 for predicting ACL injuries\u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e. Having said all of the above, during the rehabilitation process of CAI patients, it is important to not only improve the strength of the ankle eversion muscles, but also to focus on exercises that enhance body posture control. Implementing this approach could effectively mitigate knee joint compensation in patients with CAI, thus providing a preventive measure against the occurrence of ACL injuries\u003csup\u003e[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis study found that CAI patients who had experienced more than five ankle sprains exhibited a larger vertical GRF during single-leg landing. This was because CAI patients developed a strategy to protect the ankle after multiple sprains, often completing the landing with a lower ankle dorsiflexion angle, which reduced the proportion of energy absorbed at the ankle. While this strategy might enhance ankle stability to some extent, it did not promote landing cushioning and tended to result in a higher vertical GRF\u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e. Weinhandl et al\u003csup\u003e[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e]\u003c/sup\u003e discovered a positive correlation between vertical GRF and ACL loading through forward kinetic modeling, which was consistent with the findings of this study. This was due to the fact that a higher vertical GRF increased the overall loading rate of the lower extremity and the load on the ACL\u003csup\u003e[\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]\u003c/sup\u003e. The above results highlight the importance of enhancing ankle sagittal plane mobility in prevention of ACL injuries. In addition, because the hip extensors were stronger than the knee and ankle extensors, increasing the hip\u0026rsquo;s contribution to energy absorption might be beneficial in reducing knee compensation in CAI patients\u003csup\u003e[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSerpell et al\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e demonstrated that the biceps femoris frequently contracts in conjunction with the vastus lateralis muscles, resulting in increased anterior-posterior tibial displacement and passive stretching of the ACL by approximately 0.52 mm. In addition, sustained contraction of the biceps femoris during exercise could cause muscle strain and contractile inhibition, leading to an imbalance of forces around the knee that may further aggravate ACL load\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e. The present study found that CAI patients with four ankle sprains demonstrated greater biceps femoris muscle strength during exercise, which positively correlated with ACL loading, consistent with previous research\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e. Increased biceps strength during landing in CAI patients might be due to the fact that ankle instability might affect sensorimotor control at the level of the spine, thus altering the feed-forward mechanisms of the lower extremity joints, and finally causing the biceps femoris to be activated prior to landing and increasing the load on the ACL. Serpell et al\u003csup\u003e[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]\u003c/sup\u003e conducted a study which concluded that intentional activation of both the biceps femoris and the vastus medialis could reduce anteroposterior displacement of the tibia and ACL elongation by 1.2 mm and 2.0 mm, respectively. Therefore, co-activation training of the biceps femoris and vastus medialis could play an important role in minimizing ACL injuries in CAI patients.\u003c/p\u003e \u003cp\u003eThis study found that CAI patients with more than 5 ankle sprains exhibited greater rectus femoris muscle force during the landing phase. This was attributed to the limited ankle dorsiflexion in CAI patients, which reduced the energy absorption capacity of the ankle joint. As a result, patients had to maintain higher knee extensor muscle force to absorb the residual GRF\u003csup\u003e[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]\u003c/sup\u003e. In accordance with the findings of Li et al\u003csup\u003e[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/sup\u003e, the application of a force measuring 200 N to the rectus femoris muscle during knee extension yielded a pronounced increase in the anteroposterior displacement of the tibia, concomitant with an approximate 70 N augmentation in the load exerted on the ACL. Furthermore, co-contraction of the quadriceps and hamstrings further increased the ACL force, and if it exceeded 2020 N, a serious ACL injury might occur\u003csup\u003e[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/sup\u003e. It was suggested that patients with CAI should first focus on improving the flexibility of the ankle joint in the sagittal plane, increasing the energy absorption capacity of the ankle joint during landing, and reducing the cushioning load on the rectus femoris muscle.\u003c/p\u003e \u003cp\u003eThe gastrocnemius and soleus muscles together form the triceps surae muscles, which are responsible for keeping the body upright and play a crucial role in maintaining the stability of the ankle and knee joints. A study utilizing a 2D geometric model discovered that activation of the gastrocnemius and soleus muscles resulted in a reduction of ACL strain at all knee flexion angles\u003csup\u003e[\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e]\u003c/sup\u003e. In a subsequent study, Ali et al\u003csup\u003e[\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e]\u003c/sup\u003e simulated a single-leg landing maneuver and found that full activation of the gastrocnemius muscle had a protective effect on the ACL. The present results indicate that CAI patients with more than five ankle sprains exhibited lower gastrocnemius and soleus muscle strength during single-leg landing, which increased the load on the ACL. The reason for this might be that the motor neuron pools of the gastrocnemius, soleus and quadriceps muscles are interconnected. Patients with CAI often experience increased rectus femoris muscle strength during exercise, which inhibits the activation of the gastrocnemius and soleus muscles. These biomechanical characteristics decrease the muscle\u0026rsquo;s ability to protect the ACL, resulting in a significant increase in ACL load\u003csup\u003e[\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]\u003c/sup\u003e. This finding highlights the importance of improving ankle energy absorption and reducing rectus femoris muscle tension during exercise in patients with CAI.\u003c/p\u003e \u003cp\u003eIn summary, although the results of this study can help to understand the relationship between lower extremity movement patterns and ACL load in CAI patients with different numbers of ankle sprains, there are some limitations. For example, this study only explored participants who had experienced 2, 3, 4, 5 or 6 or more ankle sprains, and future studies could further subdivide the \u0026ldquo;6 or more\u0026rdquo; category so that the results of the study can be more targeted.\u003c/p\u003e"},{"header":"5 Conclusion","content":"\u003cp\u003ePatients with CAI who have experienced more than four ankle sprains within a year exhibited knee compensation and increased ACL load during single-leg landing. Limited ankle dorsiflexion, increased ankle inversion angle, excessive vertical GRF, and insufficient gastrocnemius and soleus muscle strength might increase ACL load. Therefore, patients with more than four ankle sprains should focus on increasing ankle dorsiflexion, performing rehabilitation of the ankle evertor, plantar flexor, and knee extensor muscle groups, and consider adjusting the energy absorption patterns of the lower extremity joints to more effectively cushion GRF, and reduce ACL load.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthical Approval:\u003c/strong\u003e \u003cp\u003e The study was performed in accordance with the ethical standards of the Declaration of Helsinki given ethics approval was obtained from the Ethics Committee of East China Normal University on 11 December 2023.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThe authors have not received a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eZeyi Zhang and Youping Sun was responsible for the conception and design of the study and data collection; Zeyi Zhang, Shengmeng Wei and Hanlin Shi were involved in the processing and statistical analysis of data; Zeyi Zhang were involved in the drafting of the manuscript; and all authors contributed to the interpretation of the data for the work and revising it critically for important intellectual content. All the authors finally approved the manuscript. Youping Sun was responsible for obtaining project funding and takes responsibility for the integrity of the work as a whole. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\u003ch2\u003eAvailability of data and materials:\u003c/h2\u003e \u003cp\u003eThe datasets generated and/or analysed during the current study are not publicly available due the pending closure of the relevant research project but are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePatient involvement statement:\u003c/strong\u003e Study participants were not involved in the design, conduct, interpretation, or translation of the current research.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData sharing statement:\u0026nbsp;\u003c/strong\u003eAll data used in this study are available upon request. For requests of the raw data, please contact Zeyi Zhang ([email protected]). The raw data from this study can be used for review studies (e.g., meta-analyses).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eHERZOG M M, KERR Z Y, MARSHALL S W, et al.Epidemiology of Ankle Sprains and Chronic Ankle Instability[J]. J Athl Train,2019,54(6):603-610.\u003c/li\u003e\n\u003cli\u003eVAN RIJN R M, VAN OS A G, BERNSEN R M, et al.What is the clinical course of acute ankle sprains? A systematic literature review[J]. Am J Med,2008,121(4):324-331.e326.\u003c/li\u003e\n\u003cli\u003eHERTEL J, CORBETT R O.An Updated Model of Chronic Ankle Instability[J]. J Athl Train,2019,54(6):572-588.\u003c/li\u003e\n\u003cli\u003eMOISAN G, DESCARREAUX M, CANTIN V.Effects of chronic ankle instability on kinetics, kinematics and muscle activity during walking and running: A systematic review[J]. 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Phys Ther Sport,2019,37:210-219.\u003c/li\u003e\n\u003cli\u003eZHAO X, GU Y.Single leg landing movement differences between male and female badminton players after overhead stroke in the backhand-side court[J]. Hum Mov Sci,2019,66:142-148.\u003c/li\u003e\n\u003cli\u003eTERADA M, PFILE K R, PIETROSIMONE B G, et al.Effects of chronic ankle instability on energy dissipation in the lower extremity[J]. Med Sci Sports Exerc,2013,45(11):2120-2128.\u003c/li\u003e\n\u003cli\u003eROSEN A B, JAFFRI A, MITCHELL A, et al.Association of Ankle Sprain Frequency With Body Mass and Self-Reported Function: A Pooled Multisite Analysis[J]. J Sport Rehabil,2022,31(8):1000-1005.\u003c/li\u003e\n\u003cli\u003eKRAMER L C, DENEGAR C R, BUCKLEY W E, et al.Factors associated with anterior cruciate ligament injury: history in female athletes[J]. J Sports Med Phys Fitness,2007,47(4):446-454.\u003c/li\u003e\n\u003cli\u003eGRIBBLE P A, DELAHUNT E, BLEAKLEY C, et al.Selection criteria for patients with chronic ankle instability in controlled research: a position statement of the International Ankle Consortium[J]. J Orthop Sports Phys Ther,2013,43(8):585-591.\u003c/li\u003e\n\u003cli\u003eHERMENS H J, FRERIKS B, DISSELHORST-KLUG C, et al.Development of recommendations for SEMG sensors and sensor placement procedures[J]. J Electromyogr Kinesiol,2000,10(5):361-374.\u003c/li\u003e\n\u003cli\u003eH\u0026eacute;BERT-LOSIER K, SCHELIN L, TENGMAN E, et al.Curve analyses reveal altered knee, hip, and trunk kinematics during drop-jumps long after anterior cruciate ligament rupture[J]. Knee,2018,25(2):226-239.\u003c/li\u003e\n\u003cli\u003eBAGWELL J J, AVILA E, REYNOLDS N, et al.Running biomechanics differ during and after pregnancy compared to females who have never been pregnant[J]. Gait Posture,2024,109:277-283.\u003c/li\u003e\n\u003cli\u003eBŁAŻKIEWICZ M, WIT A.Compensatory strategy for ankle dorsiflexion muscle weakness during gait in patients with drop-foot[J]. Gait Posture,2019,68:88-94.\u003c/li\u003e\n\u003cli\u003eFRITZ C O, MORRIS P E, RICHLER J J.Effect size estimates: current use, calculations, and interpretation[J]. J Exp Psychol Gen,2012,141(1):2-18.\u003c/li\u003e\n\u003cli\u003eHOCH M C, ANDREATTA R D, MULLINEAUX D R, et al.Two-week joint mobilization intervention improves self-reported function, range of motion, and dynamic balance in those with chronic ankle instability[J]. J Orthop Res,2012,30(11):1798-1804.\u003c/li\u003e\n\u003cli\u003eFONG C M, BLACKBURN J T, NORCROSS M F, et al.Ankle-dorsiflexion range of motion and landing biomechanics[J]. J Athl Train,2011,46(1):5-10.\u003c/li\u003e\n\u003cli\u003eHAGINS M, PAPPAS E, KREMENIC I, et al.The effect of an inclined landing surface on biomechanical variables during a jumping task[J]. Clin Biomech (Bristol, Avon),2007,22(9):1030-1036.\u003c/li\u003e\n\u003cli\u003eXUE X, MA T, LI Q, et al.Chronic ankle instability is associated with proprioception deficits: A systematic review and meta-analysis[J]. J Sport Health Sci,2021,10(2):182-191.\u003c/li\u003e\n\u003cli\u003eHOMYK A, ORSI A, WIBBY S, et al.Failure locus of the anterior cruciate ligament: 3D finite element analysis[J]. Comput Methods Biomech Biomed Engin,2012,15(8):865-874.\u003c/li\u003e\n\u003cli\u003eORSI A D, CHAKRAVARTHY S, CANAVAN P K, et al.The effects of knee joint kinematics on anterior cruciate ligament injury and articular cartilage damage[J]. Comput Methods Biomech Biomed Engin,2016,19(5):493-506.\u003c/li\u003e\n\u003cli\u003eCHEN Q, WORTLEY M, BHASKARAN D, et al.Is the inverted surface landing more suitable in evaluating ankle braces and ankle inversion perturbation?[J]. Clin J Sport Med,2012,22(3):214-220.\u003c/li\u003e\n\u003cli\u003eKO K R, LEE H, LEE W Y, et al.Ankle strength is not strongly associated with postural stability in patients awaiting surgery for chronic lateral ankle instability[J]. Knee Surg Sports Traumatol Arthrosc,2020,28(1):326-333.\u003c/li\u003e\n\u003cli\u003ePATERNO M V, SCHMITT L C, FORD K R, et al.Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sport[J]. Am J Sports Med,2010,38(10):1968-1978.\u003c/li\u003e\n\u003cli\u003eJEON H G, LEE S Y, PARK S E, et al.Ankle Instability Patients Exhibit Altered Muscle Activation of Lower Extremity and Ground Reaction Force during Landing: A Systematic Review and Meta-Analysis[J]. J Sports Sci Med,2021,20(2):373-390.\u003c/li\u003e\n\u003cli\u003eWEINHANDL J T, O\u0026apos;CONNOR K M.Influence of ground reaction force perturbations on anterior cruciate ligament loading during sidestep cutting[J]. Comput Methods Biomech Biomed Engin,2017,20(13):1394-1402.\u003c/li\u003e\n\u003cli\u003ePOLLARD C D, SIGWARD S M, POWERS C M.ACL Injury Prevention Training Results in Modification of Hip and Knee Mechanics During a Drop-Landing Task[J]. Orthop J Sports Med,2017,5(9):2325967117726267.\u003c/li\u003e\n\u003cli\u003eSERPELL B G, SCARVELL J M, PICKERING M R, et al.Medial and lateral hamstrings and quadriceps co-activation affects knee joint kinematics and ACL elongation: a pilot study[J]. BMC Musculoskelet Disord,2015,16:348.\u003c/li\u003e\n\u003cli\u003eLI Y, KO J, WALKER M A, et al.Does chronic ankle instability influence lower extremity muscle activation of females during landing?[J]. J Electromyogr Kinesiol,2018,38:81-87.\u003c/li\u003e\n\u003cli\u003eLI G, RUDY T W, SAKANE M, et al.The importance of quadriceps and hamstring muscle loading on knee kinematics and in-situ forces in the ACL[J]. J Biomech,1999,32(4):395-400.\u003c/li\u003e\n\u003cli\u003eADOUNI M, SHIRAZI-ADL A, MAROUANE H.Role of gastrocnemius activation in knee joint biomechanics: gastrocnemius acts as an ACL antagonist[J]. Comput Methods Biomech Biomed Engin,2016,19(4):376-385.\u003c/li\u003e\n\u003cli\u003eALI N, ANDERSEN M S, RASMUSSEN J, et al.The application of musculoskeletal modeling to investigate gender bias in non-contact ACL injury rate during single-leg landings[J]. Comput Methods Biomech Biomed Engin,2014,17(14):1602-1616.\u003c/li\u003e\n\u003cli\u003eSEDORY E J, MCVEY E D, CROSS K M, et al.Arthrogenic muscle response of the quadriceps and hamstrings with chronic ankle instability[J]. J Athl Train,2007,42(3):355-360.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Footnotes","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003e \"Segments\" is a body part that can move around a joint axis, such as the head, trunk, upper limbs, or lower limbs. It can also refer to a part of a limb, such as the hand, forearm, upper arm, foot, calf, or thigh.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-neuroengineering-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jner","sideBox":"Learn more about [Journal of NeuroEngineering and Rehabilitation](http://jneuroengrehab.biomedcentral.com/)","snPcode":"12984","submissionUrl":"https://submission.nature.com/new-submission/12984/3","title":"Journal of NeuroEngineering and Rehabilitation","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"ankle sprain frequencies, CAI patients, ACL loading, biomechanics, OpenSim modelling","lastPublishedDoi":"10.21203/rs.3.rs-4419864/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4419864/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo investigate the relationship between the biomechanical characteristics of lower extremity and anterior cruciate ligament (ACL) loading during single-leg landing in patients with chronic ankle instability (CAI) who have different ankle sprain frequencies within a year.\u003c/p\u003e\u003ch2\u003eStudy Design:\u003c/h2\u003e \u003cp\u003eCross-sectional study; Level of evidence, 3.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eAnkle sprain occurrences among 74 participants were meticulously documented over one year. The participants were systematically classified into groups based on the monitoring data regarding the frequency of ankle sprains over the course of this year, ranging from 2 to 6 or more incidents. Kinematic, kinetic, and electromyographic data were collected while participants performed a single-leg landing task. Lower extremity muscle force and ACL loading were modeled using OpenSim software.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eCAI patients with more than four ankle sprains had higher peak ACL loading during single-leg landing than those with only two or three ankle sprains (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Additionally, CAI patients with more than four ankle sprains exhibited a limited range of ankle dorsiflexion and biceps femoris muscle strength, which was significantly correlated with ACL loading (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05). CAI patients with more than 5 ankle sprains had greater ankle inversion angle, inversion angular velocity, vertical ground reaction force (GRF), rectus femoris muscle strength, and lower gastrocnemius, soleus muscle force during single-leg landing, and these biomechanical indices were significantly correlated with ACL strain (\u003cem\u003eP\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eBased on these findings, it appears that experiencing four ankle sprains within a year might be a threshold for the development of knee compensation in CAI patients. This compensation could result in a significant increase in ACL loading. The study also found that CAI patients with more than four ankle sprains commonly exhibited altered motor characteristics such as limited ankle dorsiflexion angle, increased ankle inversion angle, excessive vertical GRF, and insufficient gastrocnemius and soleus muscle force during the landing phase. These characteristics might be responsible for the observed increase in ACL loading.\u003c/p\u003e","manuscriptTitle":"Association between Lower Extremity Movement Patterns and ACL Loading in CAI Patients Across Varied Ankle Sprain Frequencies within a Year","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-06-06 15:38:04","doi":"10.21203/rs.3.rs-4419864/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-25T13:49:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-08T12:38:30+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-04T04:25:13+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"240657532108048863446117429421864611116","date":"2024-07-02T06:49:21+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-01T06:09:12+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"85099659463606470264160198669927753073","date":"2024-06-29T03:57:58+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"90105311720684887149904796470417966925","date":"2024-06-29T01:55:53+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"174741131937566228195714450943253821940","date":"2024-06-27T16:28:27+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-06-27T13:21:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"217021841770787442106990883024743042746","date":"2024-06-27T11:56:03+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"252087438627589738708913466693506073834","date":"2024-06-26T23:15:10+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-06-26T20:25:32+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-05-21T01:48:25+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-05-21T01:48:24+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of NeuroEngineering and Rehabilitation","date":"2024-05-14T14:17:03+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-neuroengineering-and-rehabilitation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jner","sideBox":"Learn more about [Journal of NeuroEngineering and Rehabilitation](http://jneuroengrehab.biomedcentral.com/)","snPcode":"12984","submissionUrl":"https://submission.nature.com/new-submission/12984/3","title":"Journal of NeuroEngineering and Rehabilitation","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"bb1798a9-1aa8-4bfb-9103-d082dbdeb402","owner":[],"postedDate":"June 6th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-04-07T16:04:50+00:00","versionOfRecord":{"articleIdentity":"rs-4419864","link":"https://doi.org/10.1186/s12984-025-01552-9","journal":{"identity":"journal-of-neuroengineering-and-rehabilitation","isVorOnly":false,"title":"Journal of NeuroEngineering and Rehabilitation"},"publishedOn":"2025-04-04 15:57:47","publishedOnDateReadable":"April 4th, 2025"},"versionCreatedAt":"2024-06-06 15:38:04","video":"","vorDoi":"10.1186/s12984-025-01552-9","vorDoiUrl":"https://doi.org/10.1186/s12984-025-01552-9","workflowStages":[]},"version":"v1","identity":"rs-4419864","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4419864","identity":"rs-4419864","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}