Restoration of the Native Joint Line Obliquity in Total Knee Arthroplasty Benefits Hip and Ankle Function

Restoration of the Native Joint Line Obliquity in Total Knee Arthroplasty Benefits Hip and Ankle Function | 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 Article Restoration of the Native Joint Line Obliquity in Total Knee Arthroplasty Benefits Hip and Ankle Function zhijun li, Philip Winnock de Grave, Tamaya Van Criekinge, Thomas Luyckx, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6147433/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Preserving the native joint line obliquity (JLO) during total knee arthroplasty (TKA) may enhance postoperative function. This study compared inverse kinematic alignment (iKA) TKA, which preserves native JLO, with adjusted mechanical alignment (aMA) TKA, which standardizes JLO to 90°, and a healthy control group across eight functional activities. Both TKA groups exhibited hip-knee coupling patterns similar to healthy controls during gait, low step-down, high step-down, low step-up, and sit-down activities. However, the aMA group required significantly greater compensatory hip flexion during high step-up ( p = 0.005, 0.016; Bonferroni-adjusted α = 0.017), despite demonstrating a lower maximum hip flexion (102.6° ± 23.10º) compared to the healthy control group (113.33° ± 11.08º) ( p = 0.014). In contrast, the iKA group maintained hip-knee coupling patterns comparable to the healthy control group during more demanding activities, such as lunges and squats. Additionally, the aMA group exhibited reduced ankle plantarflexion compared to the healthy control group during low step-down ( p = 0.008) and gait ( p = 0.002), while the iKA group was more closely with the healthy control group. Preserving native JLO supports natural hip and ankle motion, particularly under extreme joint angles, emphasizing the need to address TKA-induced biomechanical adaptations to improve functional outcomes. Health sciences/Diseases/Rheumatic diseases/Osteoarthritis Health sciences/Health occupations/Orthopaedics Total knee arthroplasty Alignment Joint line obliquity functional activities couple of movement Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction Total knee arthroplasty (TKA) is a transformative surgical intervention for individuals with end-stage knee osteoarthritis. It aims to alleviate pain, restore function, and improve overall quality of life 1 , 2 . Despite its high success rates, achieving optimal postoperative outcomes remains challenging, particularly in replicating the biomechanical and functional characteristics of the native knee, and also the adjacent joints 3 – 5 . Among evolving surgical techniques, the preservation or modification of the native joint line obliquity (JLO) of the knee has garnered significant attention for its potential impact on postoperative kinematics and functional performance 6 – 10 . The JLO plays a pivotal role in maintaining alignment and distributing forces across the adjacent joints, such as the hip and ankle, during both static and dynamic activities 11 – 13 . The alignment of the knee is essential as it acts as a biomechanical coupler between the movement of the adjacent hip and ankle joint 14 . This coupling mechanism has provided critical insights into movement patterns during various contexts, including stroke rehabilitation, limb malalignment in children, and certain strategies during physiotherapy 15 – 18 . However, its significance within TKA remains largely underexplored, particularly concerning the interplay between surgical alignment techniques and functional biomechanics. Conventional TKA techniques such as mechanical alignment, often involve altering the native knee alignment, which can induce compensatory adaptations in adjacent joints. These adjustments may disrupt lower limb movement patterns and compromise function outcomes 19 , 20 . Specifically, the adjusted mechanical alignment (aMA) technique changes the native JLO to a perpendicular to the tibial mechanical axis. In contrast, inverse kinematic alignment (iKA) seeks to preserve the native JLO 6 , 21 , restoring knee anatomy and biomechanics more closely to native 22 , 23 , and potentially minimizing the need for compensatory adjustments in adjacent joints that might reduce the risk of disrupted lower limb mechanics and functional impairments 23 . Functional activities range from basic gait to complex movements like squats and lunges, placing distinct requirements on joint mobility and stability. The dynamic interplay between the hip, knee, and ankle joints during these tasks is critical for movement efficiency and preserving long-term joint health 24 – 27 . Existing evidence highlights compensatory adjustments in hip and ankle mechanics following TKA 28 , 29 , with reduced knee joint angle being more easily managed than similar limitations at the hip 30 . However, the specific mechanisms through which alternations to the native JLO influence compensatory strategies in adjacent joints remain underexplored. While the biomechanical coupling of the hip and knee joints has been documented in some gait and rehabilitation studies, its role in the context of TKA-specific alignment changes is less understood 27 , 31 . This study seeks to fill these knowledge gaps by examining the biomechanical and functional outcomes of preserving the native JLO through iKA, compared to aMA. By analyzing joint kinematics and coupling mechanics during eight functional activities in a gait laboratory setting, this research seeks to clarify how native JLO reconstruction affects hip and ankle movement, compensatory patterns, and functional performance. The findings are expected to enhance understanding of the role of knee alignment in optimizing postoperative outcomes and contribute to refining the surgical techniques and rehabilitation strategies for TKA. Methods Participant Selection and Ethical Review This study recruited 30 patients diagnosed with advanced-stage knee osteoarthritis, characterized by persistent, severe pain unresponsive to conservative treatments. All patients underwent robotic-assisted TKA at AZ Delta Hospital, Roeselare, Belgium whose outcomes were assessed at a two-year post-surgery. Patient selection was based on a consecutive list, provided by the hospital administration, of patients who had undergone surgery two years prior. Recruitment involved contacting potential participants via telephone, explaining the study objectives, and outlining the requirements for gait laboratory analysis. Enrollment continued until 15 patients from each surgical group (iKA and aMA) agreed to participate. Importantly, the outcome measures were not disclosed to the patients during the recruitment procession. A healthy control group consisting of 21 age and sex-matched volunteers was included. The exclusion criteria ruled out individuals older than 85 years or those with comorbidities that could affect balance or gait, such as previous lower limb trauma, neurologic conditions, or systemic disease. All participants provided informed consent for data and image use. The study received approval from the institutional review board, adhered to the Declaration of Helsinki guidelines, and was registered at Ethics Committee Research UZ/KU Leuven (S67874) and Belg.Regnr (B3222022001251). Surgical Protocol and Perioperative Management A detailed description of the surgical approach, soft tissue envelop assessment, surgical steps, the preoperative and postoperative measurements, and perioperative protocol has been previously described by Winnock de Grave et al 6 , 23 . The procedure employs a far medial subvastus approach, involving a two-layer incision of the medial joint capsule. Arthrotomy is performed at the far medial aspect, anterior to the medial collateral ligament. Upon reaching the medial tibia, the longitudinal (vertical) capsular incision is redirected 90° horizontally, parallel to the tibial plateau, extending laterally. Importantly, no soft tissues are detached from the anteromedial tibia, consistent with the principles outlined in prior studies 32 , 33 . After completing the approach, the tourniquet was deflated for the remainder of the procedure. Navigation trackers were utilized to register the femur and tibia, following the robotic surgical guide 34 . The robotic system utilized computer navigation and robotically assisted instruments (Mako, Stryker, USA), the condition of the soft-tissue envelope was integrated into the robotic platform, wherein knee ligaments were tensioned in extension (at 10° flexion) and flexion (at 90° flexion with the patella in place), either manually holding the leg or utilizing ligament tensioner or spoons 35 . The prosthetics used were cemented, cruciate retaining Triathlon TKA implant (Stryker, Kalamazoo, USA) including patellar resurfacing in all cases. aMA: The constitutional coronal limb deformity was corrected within ± 3°, with tibial resection perpendicular to the tibial mechanical axis ( Fig. 1 c d). The tibial slope matched the native medial tibial slope, and the femoral component's position was adjusted to balance the flexion gap. Soft tissue release was performed if the hip-knee-ankle (HKA) angle fell outside 177° to 183° 21 . A residual laxity of 1–2 mm in both compartments in flexion and extension was targeted. iKA: The native tibial joint line was restored by resecting equal amounts of medial and lateral tibial bone ( Fig. 1 a b). The tibial slope matched the native medial tibial slope, and the femoral component's position aimed to restore the medial joint line height in extension. Soft tissue release may be performed for the HKA outside 174° to 183° 6 . Residual laxity goals were 1–2 mm in flexion and extension, with up to 3 mm allowed flexion on the lateral side. Data Collection and Data Preprocessing Biomechanical data were collected at the 3D movement laboratory located on the KU Leuven Brugge campus, which is equipped with 12 Vicon Vero cameras, 2 Vicon Vue cameras, Vicon Nexus 2.12 Software (©Vicon Motion Systems Ltd., Oxford, UK). A blinded investigator performed the participant measurements, including weight, height, leg length, knee width, ankle width, shoulder offset, elbow width, wrist width, and hand thickness, which were entered into the Vicon system. The model then calculated parameters such as tibial torsion, thigh rotation offset, shank rotation offset, foot plantar flexion offset, foot rotation offset, and Asis-trochanter distance. The maximum joint angle was manually measured using a protractor 36 . A total of 39 reflective markers (14 mm in diameter) were placed on anatomical landmarks according to the full-body plug-in-gait model 37 , 38 . During the preparation of the participants, the Vicon system was warmed and calibration according to the instructions, trajectory tails were set to 100 frames per second. The participants kept a T-pose or 'motorbike' pose for a few seconds captured a static trial, reconstructed the trail, and created a labeling skeleton template file for the subject. View the subject data in a 3D perspective view and ensure that all markers are visible to the Vicon cameras. Run the plug-in Gait static pipeline and ensure that plug-in Gait bones (segments) are visible in the 3D perspective view. The hip joint center was determined using the functional method, where markers placed on the pelvis and thigh were used to estimate the center of rotation during dynamic movements. No knee alignment device was used for the knee or ankle joint centers. The knee joint center is determined using the modified chord function, from the global position of the hip joint center, the thigh wand marker, and the knee maker, together with the knee offset, and thigh wand angle offset from the subject measurements. The ankle joint center is calculated from the knee joint center, shank cand marker, and ankle maker with the ankle offset and shank rotation offset using the modified chord function. The participants were instructed to perform eight functional activities ( Fig. 2 ) : Gait ( Fig. 2 a-e ) Lunge ( Fig. 2 p-r ) Squat ( Fig. 2 s-u ) Low step-up (165mm) ( Fig. 2 f-h ) High step-up (280 mm) ( Fig. 2 k-m ) Low step-down (165 mm) ( Fig. 2 h-j ) High step-down (280 mm) ( Fig. 2 m-o ) Five times sit-to-stand from a chair (460 mm high) ( Fig. 2 v-x ) Each activity was performed three times at a self-selected speed, the collected data underwent processing steps including reconstruction, filtering (Woltring filter), labeling, gap filling, events creation (where event names were assigned based on the motion of the knee marker as illustrated in Fig. 3 ), cycle definition, dynamic Plug-in Gait model analysis, and calculation of cycle parameters. The trials were saved in the C3D + VSK format and exported to C3D. The output angles for all joints are calculated from the YXZ cardan angles derived by comparing the relative orientation of the segments proximal (parent) and distal (child) to the joint 39 . Hip Flexion/Extension: Hip flexion is calculated about an axis parallel to the pelvic transverse axis which passes through the hip joint center. The sagittal thigh axis is projected onto the plane perpendicular to the hip flexion axis. Hip flexion is then the angle between the projected sagittal thigh axis and the sagittal pelvic axis. A positive (Flexion) angle value corresponds to the situation in which the knee is in front of the body 39 . Knee Flexion/Extension: The sagittal shank axis is projected into the plane perpendicular to the knee flexion axis. Knee flexion is the angle in that plane between this projection and the sagittal thigh axis. The sign is such that a positive angle corresponds to a flexed knee. Ankle Dorsi/Plantar Flexion: The foot vector is projected into the foot sagittal plane. The angle between the foot vector and the sagittal axis of the shank is the foot dorsi/plantar. A positive number corresponds to dorsiflexion 39 . The movement of eight functional activities was divided into two temporal phases: (1) Forward phase, from movement initiation to maximum knee flexion, and (2) Balance phase, from maximum knee flexion to the knee extension ( Fig. 3 ) . For gait, the movement was initially divided into stance phase ( Fig. 3 a-c ) and swing phase ( Fig. 3 c-e ) 18 , and then further separated into the forward ( Fig. 3 a-b, c-d ) and balance phase ( Fig. 3 b-c, d-e ) , and for five-times sit-to-stand from a chair initially divided into one cycle (Fig. 3 v-x), sit-down equals forward phase (Fig. 3 v-w), stand-up equals balance phase (Fig. 3 w-x). The forward phases were depicted in Fig. 3 as a-b, c-d, f-g, h-i, k-l, m-n, p-q, s-t, and v-w. While the balance phases were represented in Fig. 3 as b-c, d-e, g-h, i-j, l-m, n-o, q-r, t-u, and w-x. Statistical Analysis The sample size was determined based on previous studies by De Vroey et al and McClelland 40 , 41 . Upon completion of data collection, the effect size was calculated to verify that the sample of 15 participants was sufficient for the study. The data was then exported to MATLAB (R2022b for Windows; The MathWorks, Inc, Natick, MA, USA) for further analysis. All discrete measures were evaluated for normality and homogeneity of variance before statistical analysis. A one-way ANOVA, followed by post hoc t -tests with Bonferroni-adjusted, was employed for comparisons involving variables, such as sex, age, height, weight, body mass index (BMI), leg length, and maximum joint angles. Additionally, t -tests were used to compare postoperative time, operative leg, preoperative HKA, and postoperative HKA. A significance threshold of p < 0.05 was applied for the analysis. The statistical parametric mapping (Version 0.4.10, www.spm1d.org ) one-way ANOVA was used to compare results among the three groups of the kinematic mean joint angler, followed by post hoc multiple t -tests with Bonferroni-adjusted critical p -value to identify specific differences between group pairs. The trendline R-squared (R 2 ) value was used to assess the relationship between the hip, knee, and ankle joint angles, and then segment the joint angle ranges for each activity. Results Demographics and Clinical Characteristics The mean age was 72.93 ± 6.09 years in the iKA group, 65.00 ± 8.10 years in the aMA group, and 67.48 ± 7.54 years in the healthy control group. The iKA group had a mean weight of 88.30 ± 14.80 kg, the aMA group had a mean weight of 92.90 ± 10.00 kg, and the healthy control group had a mean weight of 76.70 ± 9.20 kg. No significant differences were found among the three groups for height (F (2, 48) = 0.25, p = 0.779), BMI (F (2, 48) = 0.07, p = 0.933), or leg length (right leg: F (2, 48) = 1.16, p = 0.321; left leg: F (2, 48) = 1.15, p = 0.326). No significant differences were observed in preoperative HKA alignment. Postoperative HKA alignment showed significant differences ( p = 0.006), with the iKA group (-1.72° ± 2.04°) exhibiting less neutral alignment compared to the aMA (0.05° ± 1.54°). The demographics and clinical characteristics of participants across study groups are displayed in Table 1 . Four participants in the aMA group were unable to complete the high step-up and high step-down tasks, while two participants in the iKA group could not perform these tasks. Additionally, one participant in the healthy control group was excluded from the functional activities analysis due to issues with Vicon system calibration. Table 1 Demographics and clinical characteristics of participants across study groups iKA ( n = 15 ) aMA ( n = 15) HC ( n = 21) ANOVA Post hoc (t-tests) mean ± SD mean ± SD mean ± SD F P Sex (m/f) 10/5 9/6 12/9 0.16 0.852 N/A Age (year) 72.93 6.09 65.00 8.10 67.48 7.54 4.66 0.014 A: 0.005; B: 0.027.; C:0.353 Leg length Right (m) 0.90 0.05 0.86 0.05 0.88 0.06 1.16 0.321 N/A Leg length Left (m) 0.90 0.05 0.87 0.05 0.88 0.06 1.15 0.326 N/A Height (m) 1.69 0.10 1.68 0.07 1.68 0.09 0.25 0.779 N/A Weight (kg) 88.30 14.80 92.90 10.0 76.70 9.20 15.39 0.000 A: 0.329 ; B:<0.001; C:0.001 BMI (kg/m 2 ) 30.80 4.30 33.10 5.00 27.30 3.00 0.07 0.933 N/A Postop (months) 21.10 4.80 24.40 3.20 0.171 Operated leg (left/right) 8/11 9/8 0.529 HKA preop (°, - varus) -3.10 4.50 -2 4.60 0.500 HKA postop (°, - varus) -1.72 2.04 0.05 1.54 0.006 Note. iKA = inverse kinematic alignment total knee arthroplasty; aMA = adjusted mechanical alignment total knee arthroplasty; HC = healthy control; BMI = body mass index; SD = standard deviation; n: number; m/f: male/female; m: meter; kg: kilogram; (°) = degree; ANOVA: One-way analysis of variance; F: F-statistic derived from one-way analysis of variance; P : p -value from one-way analysis of variance; statistical significance was set at p < 0.05, bold values indicate a significant difference between groups; A:significant difference between iKA and aMA; B: significant difference between iKA and HC; C: significant difference between aMA and HC. N/A: Not Applicable. Clinical Examination of Maximum Joint Angle The maximum joint angles of the hip, knee, and ankle, as manually measured using a protractor, are presented in Table 2 . Hip flexion angles were 111.11° ± 12.05° in the iKA group, 102.06° ± 23.10° in the aMA group, and 113.33° ± 11.08° in the healthy control group. Statistical analysis revealed a significant difference across the three groups (F (2, 75) = 3.60, p = 0.032), with post hoc comparisons indicating a significant difference between the aMA and healthy control group ( p = 0.014). Similarly, the hip extension was recorded as 11.26° ± 4.94° in the iKA group, 9.44° ± 5.02° in the aMA group, and 13.24° ± 5.01° in the healthy control group, with a significant overall group effect (F (2, 75) = 4.91, p = 0.010), post hoc analysis revealed a significance difference between the aMA and healthy control groups ( p = 0.003). In contrast, no significant differences were observed for knee extension across the groups. However, knee flexion values were significantly different among the groups, with the iKA group showing 120.47° ± 7.65°, the aMA group showing 109.59° ± 18.28°, and the healthy control group showing 136.21° ± 9.37°. The iKA and aMA groups exhibited significantly reduced knee flexion compared to the healthy control group (p < 0.001). No significant differences were detected in the ankle joint angles. Table 2 Manual measurement of hip, knee, and ankle maximum joint angles using a protractor. iKA ( n = 19) aMA ( n = 17) HC ( n = 42) ANOVA Post hoc mean ±SD Min ~ Max mean ± SD Min ~ Max mean ± SD Min ~ Max F P Hip flexion (°) 111.11 12.05 80 ~ 125 102.06 23.10 21 ~ 125 113.33 11.08 91 ~ 144 3.60 0.032 A:0.144; B: 0.482; C;0.014 Hip extension (°) 11.26 4.94 5 ~ 20 9.44 5.02 0 ~ 15 13.24 5.01 4 ~ 22 4.91 0.010 A:0.151; B: 0.158; C; 0.003 Hip Abduction (°) 36.26 9.63 9 ~ 50 37.47 9.25 15 ~ 50 39.88 9.52 25 ~ 68 1.07 0.347 N/A Hip adduction (°) 17.16 5.11 7 ~ 25 18.18 6.61 8 ~ 29 20.79 4.72 8 ~ 30 3.62 0.031 A:0.606; B:0.009 ; C; 0.093 Hip extern rotation (°) 29.89 9.67 15 ~ 49 34.18 8.63 15 ~ 45 33.62 9.68 12 ~ 50 1.23 0.297 N/A Hip internal rotation (°) 21.95 5.70 14 ~ 30 24.12 6.88 12 ~ 37 27.79 9.39 10 ~ 48 3.72 0.029 A:0.023; B: 0.015; C; 0.015 Knee extension (°) 2.36 2.21 0 ~ 7 3.08 2.27 0 ~ 8 1.72 3.70 -12 ~ 6 0.13 0.880 N/A Knee flexion (°) 120.47 7.65 80 ~ 130 109.59 18.28 70 ~ 135 136.21 9.37 118 ~ 160 36.68 < 0.001 A: 0.698; B: <0.001; C:<0.001 Ankle dorsiflexion 0° (°) 11.89 11.17 -10 ~ 40 7.82 4.98 0 ~ 20 11.05 5.67 0 ~ 23 1.62 0.204 N/A Ankle plantarflexion (°) 44.84 14.50 15 ~ 60 41.24 11.80 24 ~ 60 45.05 13.73 19 ~ 70 0.51 0.602 N/A Ankle dorsiflexion 90° (°) 18.21 6.82 5 ~ 30 19.47 9.04 0 ~ 35 16.45 6.41 2 ~ 29 1.19 0.310 N/A Popliteal angle (°) 33.84 10.86 19 ~ 60 31.71 15.09 0 ~ 55 31.38 12.90 10 ~ 62 0.24 0.784 N/A Note. iKA = inverse kinematic alignment total knee arthroplasty; aMA = adjusted mechanical alignment total knee arthroplasty; HC = healthy control; (°) = degree; SD = standard deviation; n: number; ANOVA: One-way analysis of variance; F: F-statistic derived from one-way analysis of variance; P: p -value from one-way analysis of variance; statistical significance was set at p < 0.05, bold values indicate a significant difference between groups; A:significant difference between iKA and aMA; B: significant difference between iKA and HC; C: significant difference between aMA and HC. N/A: Not Applicable. Coupled Movement Between Hip and Knee The coupled movement of the hip and knee during the forward phase of the eight activities is shown in Fig. 4 . Both the iKA and aMA groups displayed slightly lower R 2 values compared to the healthy control group while maintaining a consistent relationship with the healthy control group when the knee flexion is below 110° and hip flexion less than 100°, as observed during gait, low step-down, high step-down, low step-up, and sit-down (Fig. 4 a-f). When the knee flexion exceeded 110° and the hip flexion remained below 100°, the aMA group maintained a similar R 2 value to the healthy control group (Fig. 4 g). However, one-way ANOVA and post hoc revealed a significant difference in hip joint angles between the aMA and healthy control groups during the high step-up activity (Fig. 5 c & Fig. 6 d), while no significant difference between the iKA and healthy control groups (Fig. 5 c & Fig. 6 e). Furthermore, when the knee flexion exceeded 110° and the hip flexion surpassed 100°, the R 2 value and hip joint angle for the aMA group significant difference from that of the healthy control group. However, there were no significant differences between the iKA and healthy control groups. This was particularly evident during the lunge and squat activities ( Fig. 4 h, i ) , specifically, during the lunge, the R 2 values for the aMA group decreased to 0.160 ( p < 0.001), compared to values of 0.731 ( p = 0.013) and 0.611 ( p < 0.001) for the iKA and healthy control groups, respectively ( Fig. 4 h ). During the squat, the R 2 value for the aMA group was 0.292 ( p < 0.001), while the values for the iKA and healthy control groups were 0.741 ( p = 0.058) and 0.805 ( p = 0.321), respectively ( Fig. 4 i ). Hip Flexion Angles During Step-up. Figure 5 illustrates that the hip flexion in the low step-up task of a significant difference among the three groups between 0% and 11%, as well as between 23% and 33% of the low step-up phase (Fig. 5 a b ; +8.93, F (2, 62) = 5.95, p = 0.016 & p = 0.018). However, during the high step-up, a significant difference in hip flexion among the three groups between 0% and 30%, and between 89% and 100% (Fig. 5 c d ; +11.45, F (2, 56) = 5.21, p = 0.004 & p = 0.038). The results of the post hoc analysis are shown in Fig. 6 , which further confirms significant differences between the aMA and healthy control groups during high step-up (Fig. 6 a; t = 3.15, p = 0.005 & p = 0.016), and the post hoc multiple t -tests with Bonferroni-adjusted critical p -value: α = 0.017, whereas no significant difference was observed between iKA and healthy control groups (Fig. 6 b). Ankle Flexion During Functional Activities The ankle angle results of one-way ANOVA and mean comparisons during low step-down and gait cycles are presented in Fig. 7 . There is significantly reduced ankle plantarflexion compared to the healthy control group between 44% and 48% of the low step-down (Fig. 7 a b ; -4º, F (2, 62) = 6.82, p = 0.035). This difference was confirmed by post hoc analysis between the aMA and healthy control groups (Fig. 8 a; t = 3.68, p = 0.008). No significant differences were observed for the iKA group during this phase. Furthermore, during the gait cycle, there was exhibited significantly different ankle plantarflexion among the three groups between 50% and 70%, as well as between 84% and 97% of the gait cycle (Fig. 7 c d ; -7.41º, F (2, 63) = 6.08, p = 0.007 and p = 0.021, respectively). Post hoc analysis further revealed that the aMA group exhibited significantly reduced plantarflexion compared to the HC group (Fig. 8 d; t = 3.38, p = 0.002). Additionally, the iKA group displayed significant differences compared to the aMA group (Fig. 8 f; t = 3.40, p = 0.006 & p = 0.004). Discussion This study investigates the impact of the restoration of the native JLO on functional activities following TKA. Our findings demonstrate that preserving the native JLO effectively maintains the natural joint kinematics between the hip, knee, and ankle, enabling physiologically accurate movement patterns. The effect of JLO preservation particularly becomes evident in activities requiring extreme joint angles, such as high step-up, lunge, and squat, where hip movement more closely resembles natural biomechanics with iKA, compared to aMA. Additionally, during gait and low step-down activities, the ankle plantarflexion angle in the iKA group closely approximates that of the HC group, underscoring the biomechanical advantage of retaining the native JLO. The coupled movement between the hip and knee refers to their interdependent motion, wherein the movement at one joint directly influences and affects the movement at the other joint 42 . This interdependence arises from shared muscle groups and the bony alignment of the lower limb, which together facilitate coordinated movement patterns 17 , 43 . This study provides the first comprehensive examination of this relationship across multiple functional activities within the TKA domain. During activities requiring knee flexion angles no more than 110 degrees and hip flexion angles no more than 100 degrees, such as gait, low step-down, high step-down, sit-to-stand, low step-up, both the aMA and iKA groups exhibited R 2 values comparable to each other, though slightly lower than those of the HC group ( Fig. 4 a-f ) . In activities requiring knee flexion angle exceeding 110 degrees and hip flexion angles no more than 100 degrees, such as high step-up, the R 2 values for the aMA and iKA groups remained closely aligned with those of the HC group (Fig. 4 g). However, during high step-up activities, which approaches the maximum knee flexion threshold of the aMA group (109.59º ± 18.28º; Table 2 ) , the aMA group required significantly greater hip flexion angles to complete the movement ( Fig. 5 c d & Fig. 6 a ). This pattern is consistent with previous research indicating altered movement patterns in TKA patients during functional activities 19 , 20 , 44 , 45 . When the prosthetic knee flexion angle is restricted, compensatory adjustments in the hip motion are required to meet functional demands 46 . Notably, four participants in the aMA group were unable to complete this task due to its biomechanical demands. During activities requiring knee flexion angles surpassing 110 degrees and hip flexion angles exceeding 100 degrees, such as lunge and squat, the iKA group demonstrated hip flexion angles and R 2 values closely aligned with those of the HC group. In contrast, the aMA group showed significant deviations from the HC group ( Fig. 4 h, i ) , reaching or exceeding the aMA group’s maximum knee and hip flexion thresholds. The maximum hip flexion of the aMA group (102.06º ± 23.10º) is significantly lower than the HC group (113.33º ± 11.08º; p = 0.014) (Table 2 ). These deviations may be attributed to alternations in femoral neck anteversion, defined as the angle between the femoral neck and shaft, which plays a crucial role in influencing hip biomechanics 47 . Although dynamic changes in femoral neck anteversion following total hip arthroplasty have been extensively documented 48 , its alterations post-TKA remain insufficiently explored. In varus knees treated with the aMA technique, the medial posterior condyle is typically resected 2–4 mm thicker than the lateral posterior condyle 49 , 50 , leading to modifications in femoral neck anteversion ( Fig. 1 d, f ) . Such changes may restrict hip flexion angles during demanding tasks, such as lunge and squat ( Fig. 4 h, i ). Additionally, a decrease in the femoral abduction angle may modestly affect the effectiveness of the aMA group in these activities ( Fig. 1 c, e ) . In contrast, the iKA technique preserves the native distal femoral anatomy, maintaining a more natural femoral neck anteversion (Fig. 1 b, f), which contributes to R 2 values and mean hip joint angles comparable to those of the HC group during these activities ( Fig. 4 h, i ) . The maximum hip flexion observed in the iKA group (111.11º ± 12.05º) compared to the HC group (113.33º ± 11.08º; p = 0.482) further supports this finding (Table 2 ). Our results also reveal that during gait and low step-down activities, the plantarflexion ankle angle in the aMA group significantly differs from that of the HC group ( Fig. 7 a-d & Fig. 8 a d) . Conversely, the iKA group exhibits ankle plantarflexion angles closely approximating those of the HC group (Fig. 7 a-d & Fig. 8 b e ). Previous research has shown that perpendicular cuts to the tibial mechanical axis lead to alterations in the alignment of the ankle joint line, which is consistent with our findings 51 – 53 . Restoration of the native JLO is crucial for preserving not only knee biomechanics but also the natural alignment and function of the ankle 54 . When the native JLO is altered to 90 degrees in the aMA approach ( Fig. 1 c d) , even a small angular change at the knee can translate through the tibia to produce a significantly exaggerated angular change at the ankle, particularly in activities requiring plantarflexion, such as gait and low step-down ( Fig. 7 & Fig. 8 ) . This may also explain previous findings that foot orientation during gait differs from natural patterns after mechanical alignment TKA 23 , 26 . This study has several limitations. While sagittal plane movements were recorded accurately using the Vicon system, measurements in the coronal and transverse planes were less accurate. A more comprehensive evaluation of these planes would provide possibly more insights into the movements post-TKA. Although weight differences were normalized within the Vicon system, they may have been influenced by the kinetic aspects of the data from the forces plane, as a result, kinetic data were excluded from this analysis. Future studies incorporating comparable kinetic data would enhance the depth of these findings. Additionally, although electromyography data on muscle activity was collected, they were not analyzed in this study as they fall outside the scope of kinematic analysis. Incorporating these data in future studies could enhance our understanding of muscle behavior during post-TKA functional activities. In conclusion, the rising prevalence of TKA underscores the importance of addressing its long-term biomechanical implications. Changes in knee alignment significantly influence not only the knee but also the hip and ankle, emphasizing the importance of considering whole-limb biomechanics. By preserving the native JLO, it is possible to achieve postoperative movement patterns more closely aligned with natural kinematics, ultimately improving functional outcomes and quality of life for TKA patients. Declarations Author Contribution All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Van Criekinge Tamaya, Winnock deGrave Philip, Luyckx Thomas, Claeys Kurt, and Li Zhijun. The first draft of the manuscript was written by Li Zhijun. Winnock de Grave Philip, Claeys Kurt commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgement We sincerely thank the staff at AZ Delta, Roeselare, Belgium, for their invaluable assistance. We would also like to express our gratitude to the Rehabilitation Sciences team at KU Leuven, Brugge, Belgium, for their continued support. We extend our appreciation to the dedicated researchers at the Bioengineering Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, USA, for their contributions to help understand the data. Data Availability The dataset of this study is not publicly available due to the ongoing nature of this 15-year project. At this stage, the raw data can not be shared or utilized; however, data accessibility will be periodically reviewed, and we will ensure compliance with ethical and regulatory guidelines as the project progresses. Data may be available from the corresponding author upon request, subject to approval by the ethics committees of KU Leuven University and AZ Hospital. References Krummenauer, A., C. Wolf, K.-P. Günther & S. Kirschner. Clinical benefit and cost-effectiveness of total knee arthroplasty in the older patient. Eur. J. Med. Res. 14 , 76–84 (2009). Kurtz, S., Ong, K., Lau, E., Mowat, F. & Halpern, M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J. Bone Jt. Surg. 89 , 780–785 (2007). Beringer, D. C., Patel, J. J. & Bozic, K. J. An overview of economic issues in computer-assisted total joint arthroplasty. Clin. Orthop. Relat. Res. 463 , 26–30 (2007). Schönthaler, W., Dauwe, J. & Holzer, L. A. Patient-specific instrumentation in total knee arthroplasty: a review of the current literature. Acta Orthop. Belg. 89 , 299–306 (2023). Deep, K., Shankar, S. & Mahendra, A. Computer-assisted navigation in total knee and hip arthroplasty. 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Arthroplasty 32 , 575–580 (2017). Simon, S. R. Gait Analysis, Normal and Pathological Function. J. Bone Jt. Surg. 75 , 476–477 (1993). Wang, G. et al. Modified kinematic alignment better restores plantar pressure distribution than mechanical alignment in total knee arthroplasty: a randomized controlled trial. Sci. Rep. 14 , 1–9 (2024). Nazlıgül, A. S., Doğan, M., Duran, İ., Moya-Angeler, J. & Akkaya, M. Mid-Term Clinical and Radiological Changes in the Ankle Joint in Varus Knee Osteoarthritis Following Total Knee Arthroplasty. J. Clin. Med. 13 , (2024). Miner, A. L. et al. Knee range of motion after total knee arthroplasty: How important is this as an outcome measure? J. Arthroplasty 18 , 286–294 (2003). Vélez Día, D. & Moreno Gutiérrez, S. S. Biomechanics and Motor Control of Human Movement . XIKUA Boletín Científico de la Escuela Superior de Tlahuelilpan vol. 1 (2013). Thienpont, E. Faster quadriceps recovery with the far medial subvastus approach in minimally invasive total knee arthroplasty. Knee Surgery, Sport. Traumatol. Arthrosc. 21 , 2370–2374 (2013). Koninckx, A., Schwab, P. E., Deltour, A. & Thienpont, E. The minimally invasive far medial subvastus approach for total knee arthroplasty in valgus knees. Knee Surgery, Sport. Traumatol. Arthrosc. 22 , 1765–1770 (2014). Stryker Corporation. MAKO TKA Surgical Guide. Stryker Robot. Arm Syst. (2016). Weber, P. & Gollwitzer, H. Kinematic alignment in total knee arthroplasty. Oper. Orthop. Traumatol. 33 , 525–537 (2021). Swaney, S. Measurement of Joint Motion: A guide to goniometry. Physiotherapy vol. 82 278 (1996). Davids, J. R., Ounpuu, S., DeLuca, P. A. & Davis, R. B. Optimization of the walking ability of children with cerebral palsy. Instr. Course Lect. 53 , 511–522 (2004). Roy B. Davis III, Sylvia Õunpuu, Tyburski, D. & James R. Gage. A gait analysis data collection and reduction technique. Hum. Mon. Sci. 10 , 575–587 (1991). Vicon Motion Systems. Plug-in Gait Reference Guide. Vicon Nexus 2.10 User Man. Ref. Guid 53–54 (2020). De Vroey, H. et al. Hip and knee kinematics of the forward lunge one year after unicondylar and total knee arthroplasty. J. Electromyogr. Kinesiol. 48 , 24–30 (2019). McClelland, J. A., Feller, J. A., Menz, H. B. & Webster, K. E. Patients with total knee arthroplasty do not use all of their available range of knee flexion during functional activities. Clin. Biomech. 43 , 74–78 (2017). Frigo, C., Crenna, P. & Jensen, L. M. Moment-angle relationship at lower limb joints during human walking at different velocities. J. Electromyogr. Kinesiol. 6 , 177–190 (1996). de Sousa, A. M. M. et al. The Influence of Hip and Knee Joint Angles on Quadriceps Muscle-Tendon Unit Properties during Maximal Voluntary Isometric Contraction. Int. J. Environ. Res. Public Health 20 , (2023). Capin, J. J., Bade, M. J., Jennings, J. M., Snyder-Mackler, L. & Stevens-Lapsley, J. E. Total Knee Arthroplasty Assessments Should Include Strength and Performance-Based Functional Tests to Complement Range-of-Motion and Patient-Reported Outcome Measures. Phys. Ther. 102 , 1–10 (2022). Farquhar, S. J., Reisman, D. S. & Snyder-Mackler, L. Persistence of altered movement patterns during a sit-to-stand task 1 year following unilateral total knee arthroplasty. Phys. Ther. 88 , 567–579 (2008). Van Criekinge, T., Winnock de Grave, P., Luyckx, T. & Claeys, K. Trunk control, motion and alignment after total knee arthroplasty: a systematic review and meta-analysis. Gait Posture 94 , 173–188 (2022). Scorcelletti, M., Reeves, N. D., Rittweger, J. & Ireland, A. Femoral anteversion: significance and measurement. J. Anat. 237 , 811–826 (2020). Klim, S. M. et al. Femoral Anteversion in Total Hip Arthroplasty: Retrospective Comparison of Short- and Straight-Stem Models Using CT Scans. J. Clin. Med. 12 , 4–13 (2023). Wei, M., Hao, K., Kang, H., Kong, L. & Wang, F. Lateral distal femoral condyle has more uniform cartilage wear in varus knee osteoarthritis. Sci. Rep. 14 , 1–9 (2024). Liu, D. W., Martinez Martos, S., Dai, Y. & Beller, E. M. The femoral intercondylar notch is an accurate landmark for the resection depth of the distal femur in total knee arthroplasty. Knee Surg. Relat. Res. 34 , 1–7 (2022). Kim, J. T., Han, J., Lim, S., Shen, Q. H. & Won, Y. Y. Kinematically Aligned TKA Aligns the Ankle Joint Line Closer to Those of the Native Ankle than Mechanically Aligned TKA in Bipedal Stance. J. Knee Surg. 32 , 1033–1038 (2019). Jang, S. J. et al. Comparison of tibial alignment parameters based on clinically relevant anatomical landmarks a deep learning radiological analysis. Bone Jt. Open 3 , 767–776 (2022). Parcells, B. Hip and Knee Book: Comprehensive guide to TKA and THA techniques and considerations. Manasquan, NJ, USA (2017). Lee, J. H. & Jeong, B. O. Radiologic changes of the ankle joint after total knee arthroplasty. Foot Ankle Int. 33 , 1087–1092 (2012). Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 10 Jun, 2025 Reviews received at journal 09 Jun, 2025 Reviewers agreed at journal 19 May, 2025 Reviews received at journal 09 Apr, 2025 Reviewers agreed at journal 31 Mar, 2025 Reviewers agreed at journal 31 Mar, 2025 Reviewers invited by journal 31 Mar, 2025 Editor assigned by journal 31 Mar, 2025 Editor invited by journal 19 Mar, 2025 Submission checks completed at journal 17 Mar, 2025 First submitted to journal 03 Mar, 2025 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6147433","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":440714887,"identity":"686b7ff6-cfce-4f95-9432-b3c1484f86ca","order_by":0,"name":"zhijun li","email":"","orcid":"","institution":"KU Leuven","correspondingAuthor":false,"prefix":"","firstName":"zhijun","middleName":"","lastName":"li","suffix":""},{"id":440714888,"identity":"0fd1b77f-f67b-491b-bb43-803b5e0de701","order_by":1,"name":"Philip Winnock de Grave","email":"","orcid":"","institution":"KU Leuven","correspondingAuthor":false,"prefix":"","firstName":"Philip","middleName":"Winnock","lastName":"de Grave","suffix":""},{"id":440714889,"identity":"3edd260b-6973-47eb-b3fe-917a604479a2","order_by":2,"name":"Tamaya Van Criekinge","email":"","orcid":"","institution":"KU Leuven","correspondingAuthor":false,"prefix":"","firstName":"Tamaya","middleName":"Van","lastName":"Criekinge","suffix":""},{"id":440714890,"identity":"d5ae7e53-5c23-4d37-9d73-d5b26c362446","order_by":3,"name":"Thomas Luyckx","email":"","orcid":"","institution":"KU Leuven","correspondingAuthor":false,"prefix":"","firstName":"Thomas","middleName":"","lastName":"Luyckx","suffix":""},{"id":440714891,"identity":"ea561adb-b318-4760-8142-4d2489569c2a","order_by":4,"name":"Kurt Claeys","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/UlEQVRIiWNgGAWjYBACCQhlASIYHzZAGEBmA14tIGmwTmbDBpgRxGphkyRKi+SM3OcPGGok5Pkl0p9VzmyTkDO4kXzsAeMOG5xapCXSgc45JmE4c0aO2c2NbRLGBjfS0g0Yz6Th1CInkcbYwNggwbjhRg7bzYdtEokbzpwxk2BsO0xQi/3+G+nPCoFa6jecOf8NqOU/HodBtCRukEgwYwQ6LMHgeA8bUMsB3N7vecY4I+GYRPKMM2+MJWecA3rqeJuZROKZZJxaJI6nMXz4UGNj29+e/vBjT5mNPN9h5mcSH3fY4dQCBgkgQiABXYQg4Mft+lEwCkbBKBjhAACcpVPABvWFBQAAAABJRU5ErkJggg==","orcid":"","institution":"KU Leuven","correspondingAuthor":true,"prefix":"","firstName":"Kurt","middleName":"","lastName":"Claeys","suffix":""}],"badges":[],"createdAt":"2025-03-03 15:08:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6147433/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6147433/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":81031976,"identity":"30bebf89-8795-4490-88a8-a260d0a084bf","added_by":"auto","created_at":"2025-04-21 11:25:50","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":42542,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe bone cuts between the iKA and aMA techniques lead to differences in femoral neck anteversion and femoral abduction angles. \u0026nbsp;\u003c/strong\u003eThe iKA technique leads to a more closely natural femur neck anteversion than that of the aMA (A \u0026gt; B), and the femoral abduction angle of iKA minus the abduction angle of aMA is equal to the angle C. The principles of iKA (a, b) are shown by the black line (e, f). These principles involve performing equal bony resections medial and lateral on the tibial bone. The distal and posterior femoral cuts are determined by tensioning the ligaments and are made parallel to the tibial cut. Conversely, the principles of aMA (c, d) are represented by the red dot line (e, f). In aMA, bone cuts are made perpendicular to the mechanical line of the femur or tibia. ‘A’ angle: iKA femoral neck anteversion; ‘B’ angle: aMA femoral neck anteversion. ‘C’ angle: variations in joint line angle and femoral abduction angle are observed between the two techniques. The medial proximal tibial angle is 90 degrees in the aMA, and 87 degrees in iKA. LDFA: Lateral distal femoral angle. It is 87 degrees in aMA, but 90 degrees in iKA.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/0265bf4e239ed48637c69f4e.jpg"},{"id":81032510,"identity":"1df841ed-aa20-434b-a435-8f414bbc4fb4","added_by":"auto","created_at":"2025-04-21 11:33:50","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":114181,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eEight functional activities after reflective markers positioned on the anatomical.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e(a-e)\u003c/strong\u003egait, \u003cstrong\u003e(f-h)\u003c/strong\u003e low step-up, \u003cstrong\u003e(h-j)\u003c/strong\u003e low step-down, \u003cstrong\u003e(k-m)\u003c/strong\u003e high step-up, \u003cstrong\u003e(m-o)\u003c/strong\u003e high step-down, \u003cstrong\u003e(p-r)\u003c/strong\u003e lunge, \u003cstrong\u003e(s-u)\u003c/strong\u003e squat, \u003cstrong\u003e(v-x)\u003c/strong\u003eone cycle of sit-to-stand from a chair.\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/2eb49850e41c1d611a1fc8c5.jpg"},{"id":81031978,"identity":"86ef1472-7e94-4c95-97fe-6d7fba5bf0f2","added_by":"auto","created_at":"2025-04-21 11:25:50","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":98008,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eDifferential phases of eight functional activities divide in Vicon. \u003c/strong\u003eThe green side represents the right and the functional leg, while the red side corresponds to the left. The event naming is determined based on the motion of the knee marker, with the teal color line illustrating the trajectory of the knee marker. \u003cstrong\u003ea-e \u003c/strong\u003eGait cycle:\u003cstrong\u003e (a-c)\u003c/strong\u003e gait stance phase, (\u003cstrong\u003ec-e)\u003c/strong\u003egait swing phase, (\u003cstrong\u003ea-b)\u003c/strong\u003e forward phase in gait stance phase, (\u003cstrong\u003eb-c)\u003c/strong\u003ebalance phase in gait stance phase; (\u003cstrong\u003ec-d)\u003c/strong\u003e forward phase in gait swing phase, (\u003cstrong\u003ed-e)\u003c/strong\u003e balance phase in gait swing phase. \u003cstrong\u003ef-h \u003c/strong\u003eLow step-up cycle: \u003cstrong\u003e(f-g)\u003c/strong\u003e forward phase in low step-up, \u003cstrong\u003e(g-h) \u003c/strong\u003ebalance phase in low step-up, \u003cstrong\u003eh-j \u003c/strong\u003eLow step-down cycle: \u003cstrong\u003e(h-i) \u003c/strong\u003eforward phase in low step-down, \u003cstrong\u003e(i-j) \u003c/strong\u003ebalance phase in low step-down. \u003cstrong\u003ek-m \u003c/strong\u003eHigh step-up cycle: \u003cstrong\u003e(k-l) \u003c/strong\u003eforward phase in high step-up, \u003cstrong\u003e(l-m) \u003c/strong\u003ebalance phase in high step-up. \u003cstrong\u003em-o \u003c/strong\u003eHigh step-down cycle: \u003cstrong\u003e(m-n) \u003c/strong\u003eforward phase in high step-down, \u003cstrong\u003e(n-o) \u003c/strong\u003ebalance phase in high step-down. \u003cstrong\u003ep-r \u003c/strong\u003eLunge cycle: \u003cstrong\u003e(p-q) \u003c/strong\u003eforward phase in the lunge, \u003cstrong\u003e(q-r) \u003c/strong\u003ebalance phase in lunge. \u003cstrong\u003es-u \u003c/strong\u003eSquat cycle: \u003cstrong\u003e(s-t) \u003c/strong\u003eforward phase in the squat, \u003cstrong\u003e(t-u) \u003c/strong\u003ebalance phase in the squat. \u003cstrong\u003ev-x\u003c/strong\u003e One of the five times sit-to-stand: \u003cstrong\u003e(v-w) \u003c/strong\u003eforward phase, sit-down, \u003cstrong\u003e(w-x) \u003c/strong\u003ebalance phase, stand-up. Movement Initiation: (\u003cstrong\u003ea, c, f, h, k, m, p, s, v)\u003c/strong\u003e; Maximum knee flexion: (\u003cstrong\u003eb, d, g, i, l, n, q, t, w\u003c/strong\u003e); Knee Extension: \u003cstrong\u003e(c, e, h, j, m, o, r, u, x)\u003c/strong\u003e. %: percent. Green: the right side; Red: the left side; Orange: the trunk; Blue: the bone segments; Teal: the trajectory of the knee marker. mm: millimeters.\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/422c6a893a29d5507f1fc86b.jpg"},{"id":81031980,"identity":"f3bdbd38-0e30-4a78-a858-ac1efc4b4937","added_by":"auto","created_at":"2025-04-21 11:25:50","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":127278,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe coupled motion of the hip and knee angles during the forward phase of the eight activities.\u003c/strong\u003e \u003cstrong\u003ea-f\u003c/strong\u003e \u0026nbsp;The aMA and iKA groups show slightly lower R\u003csup\u003e2\u003c/sup\u003e values compared to the healthy control group but maintain a consistent relationship with the healthy control group such as gait \u003cstrong\u003e(a, b)\u003c/strong\u003e, low step-down \u003cstrong\u003e(c)\u003c/strong\u003e, high step-down \u003cstrong\u003e(d)\u003c/strong\u003e, low step-up \u003cstrong\u003e(e)\u003c/strong\u003e, sit-down \u003cstrong\u003e(f), \u003c/strong\u003eand\u003cstrong\u003e \u003c/strong\u003ehigh step-up \u003cstrong\u003e(g)\u003c/strong\u003e; \u003cstrong\u003eh, i\u003c/strong\u003e The R\u003csup\u003e2\u003c/sup\u003e value for the aMA group deviates from that of the HC group in the lunge \u003cstrong\u003e(h)\u003c/strong\u003e and squat \u003cstrong\u003e(i)\u003c/strong\u003e activities, with the R\u003csup\u003e2\u003c/sup\u003e values decrease to 0.160 and 0.292, respectively. Negative values represent extension join angles, while positive values indicate flexion angles. iKA: inverse kinematic alignment, aMA: adjusted mechanical alignment, HC: healthy control. p: \u003cem\u003ep\u003c/em\u003e-value, statistical significance was set at \u003cem\u003ep \u003c/em\u003e\u0026lt; 0.05. (°): degree.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/16760b8b7c8b1d6475381b28.jpg"},{"id":81032511,"identity":"e6963c2b-79f0-4daa-9f76-3c06c677a6ee","added_by":"auto","created_at":"2025-04-21 11:33:50","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":58372,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe hip flexion angle of one-way ANOVA and mean comparisons of low and high step-up.\u003c/strong\u003e \u003cstrong\u003ea b\u003c/strong\u003ethe hip flexion angle in the low step-up of the three groups was significantly different between 0% and 11%, as well as between the 23% and 33% (+8.93, F (2, 62) = 5.95, \u003cem\u003ep\u003c/em\u003e = 0.016 \u0026amp; \u003cem\u003ep\u003c/em\u003e = 0.018). (\u003cstrong\u003ea) \u003c/strong\u003eThe results of the one-way ANOVA for hip flexion during the low step-up. (\u003cstrong\u003eb)\u003c/strong\u003e The mean hip flexion during the low step-up. \u003cstrong\u003ec d\u003c/strong\u003e there were significant differences between 0% and 30% of the high step-up, and between 89% and 100% (+11.45, F (2, 56) = 5.21, \u003cem\u003ep\u003c/em\u003e = 0.004 \u0026amp; \u003cem\u003ep\u003c/em\u003e = 0.038). (\u003cstrong\u003ec) \u003c/strong\u003eThe results of the one-way ANOVA for hip flexion during the high step-up. (\u003cstrong\u003ed)\u003c/strong\u003e The mean hip flexion during the high step-up. iKA: inverse kinematic alignment, aMA: adjusted mechanical alignment, HC: healthy control. p: \u003cem\u003ep\u003c/em\u003e-value, statistical significance was set at \u003cem\u003ep \u003c/em\u003e\u0026lt; 0.05, α: alpha, Type I error rate (default: 0.05), F*: the critical Random Field Theory threshold, %: percent.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/b7461dc2ba5f459edc26b392.jpg"},{"id":81031979,"identity":"231122c8-bb02-4233-9a29-3604daf90e1f","added_by":"auto","created_at":"2025-04-21 11:25:50","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":73279,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003epost-hoc \u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003emultiple \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003et\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-test with adjusted critical \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-value analysis of hip flexion angles between two groups in low and high step-ups.\u003c/strong\u003e (\u003cstrong\u003ea)\u003c/strong\u003e There was a significant difference between the aMA and healthy control groups during low step-up (α = 0.017, \u003cem\u003et \u003c/em\u003e= 3.477, \u003cem\u003ep \u003c/em\u003e= 0.015); (\u003cstrong\u003eb)\u003c/strong\u003eThere was a significant difference between the iKA and the healthy control group in the hip flexion angle during low step-up (α = 0.017, \u003cem\u003et \u003c/em\u003e= 3.358, \u003cem\u003ep \u003c/em\u003e= 0.015 and 0.016). (\u003cstrong\u003ec)\u003c/strong\u003e There was no significant difference between the iKA and HC groups. (\u003cstrong\u003ed)\u003c/strong\u003eThere was a significant difference between the aMA and healthy control groups during high step-up (α = 0.017, \u003cem\u003et \u003c/em\u003e= 3.151, \u003cem\u003ep \u003c/em\u003e= 0.005 and p = 0.016); \u003cstrong\u003e(e)\u003c/strong\u003e There was no significant difference between the iKA and healthy control groups; (\u003cstrong\u003ef)\u003c/strong\u003e There was no significant difference between the iKA and aMA groups. iKA: inverse kinematic alignment, aMA: adjusted mechanical alignment, HC: healthy control group. α: alpha, Bonferroni-adjusted, t: \u003cem\u003epost-hoc \u003c/em\u003emultiple\u003cem\u003e t\u003c/em\u003e-statistic, p: \u003cem\u003ep\u003c/em\u003e-value, statistical significance was set at \u003cem\u003ep \u003c/em\u003e\u0026lt; α.\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/323340c84bc15e2951a6953f.jpg"},{"id":81031983,"identity":"e0be3389-deea-4769-9da6-f01e9aafd1d5","added_by":"auto","created_at":"2025-04-21 11:25:50","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":64036,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe results of one-way ANOVA and mean comparisons for ankle flexion angle during low step-down and gait. a b \u003c/strong\u003ethere was a significant difference between the three groups between 44% and 48% of the low step-down (-4º, F (2, 62) = 6.821, \u003cem\u003ep\u003c/em\u003e = 0.035). (\u003cstrong\u003ea) \u003c/strong\u003eThe results of the one-way ANOVA for ankle flexion during the low step-down. (\u003cstrong\u003eb)\u003c/strong\u003e The mean ankle flexion during the low step-down. \u003cstrong\u003ec d\u003c/strong\u003e there was a significant difference between the three groups during the 50% to 70% and 84% to 97% phases of the gait cycle (-7.41º, F (2, 63) = 6.083, \u003cem\u003ep\u003c/em\u003e = 0.007 \u0026amp; \u003cem\u003ep\u003c/em\u003e = 0.021). (\u003cstrong\u003ec) \u003c/strong\u003eThe results of the one-way ANOVA for ankle flexion during gait. (\u003cstrong\u003ed)\u003c/strong\u003e The mean ankle flexion angle during gait. iKA: inverse kinematic alignment, aMA: adjusted mechanical alignment, HC: healthy control. degree (+): ankle dorsiflexion; degree (-): ankle plantar flexion. p: \u003cem\u003ep\u003c/em\u003e-value, statistical significance was set at \u003cem\u003ep \u003c/em\u003e\u0026lt; 0.05, α: alpha, Type I error rate (default: 0.05), F*: the critical Random Field Theory threshold, %: percent.\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/2e32e42a91e029f21f4056c4.jpg"},{"id":81031984,"identity":"d7443e81-9ead-4779-b53c-4140a03b413d","added_by":"auto","created_at":"2025-04-21 11:25:50","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":75935,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003epost hoc \u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003emultiple \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003et\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-test with adjusted critical \u003c/strong\u003e\u003cem\u003e\u003cstrong\u003ep\u003c/strong\u003e\u003c/em\u003e\u003cstrong\u003e-value analysis of ankle flexion angles between two groups in low step-down and gait.\u003c/strong\u003e (\u003cstrong\u003ea)\u003c/strong\u003eThe aMA group showed a significantly different ankle plantar flexion angle than the healthy control group during low step-down (α =0.017, \u003cem\u003et \u003c/em\u003e=3.68, \u003cem\u003ep \u003c/em\u003e= 0.008). (\u003cstrong\u003eb)\u003c/strong\u003eNo significant difference was observed between the iKA and HC groups. (\u003cstrong\u003ec)\u003c/strong\u003eNo significant difference was observed between the iKA and aMA groups. (\u003cstrong\u003ed\u003c/strong\u003e) The aMA group exhibited significantly different from the healthy control group in the ankle plantar flexion angle during gaiting (α = 0.017, \u003cem\u003et \u003c/em\u003e= 3.380, \u003cem\u003ep \u003c/em\u003e= 0.002). (\u003cstrong\u003ee)\u003c/strong\u003e No significant difference was identified between the iKA and healthy control groups. \u0026nbsp;(\u003cstrong\u003ef\u003c/strong\u003e) The aMA group demonstrated a significantly different ankle flexion angle from the iKA group (α = 0.017, \u003cem\u003et \u003c/em\u003e= 3.397, \u003cem\u003ep \u003c/em\u003e= 0.007 \u0026amp; 0.004). degree (+): ankle dorsiflexion, degree (-): ankle plantar flexion. iKA: inverse kinematic alignment. aMA: adjusted mechanical alignment, HC: healthy control. α: alpha, Bonferroni-adjusted, t: \u003cem\u003epost-hoc \u003c/em\u003emultiple\u003cem\u003e t\u003c/em\u003e-statistic, p: \u003cem\u003ep\u003c/em\u003e-value, statistical significance was set at \u003cem\u003ep \u003c/em\u003e\u0026lt; α.\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/4b6cd40ace1214ddf4db1b06.jpg"},{"id":81034582,"identity":"28c00dfa-2a78-4d87-825b-237564b46c19","added_by":"auto","created_at":"2025-04-21 11:57:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2208294,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6147433/v1/9d6b92c8-d4f1-4199-851c-b1f5fd8a6a52.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eRestoration of the Native Joint Line Obliquity in Total Knee Arthroplasty Benefits Hip and Ankle Function\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTotal knee arthroplasty (TKA) is a transformative surgical intervention for individuals with end-stage knee osteoarthritis. It aims to alleviate pain, restore function, and improve overall quality of life\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Despite its high success rates, achieving optimal postoperative outcomes remains challenging, particularly in replicating the biomechanical and functional characteristics of the native knee, and also the adjacent joints\u003csup\u003e\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Among evolving surgical techniques, the preservation or modification of the native joint line obliquity (JLO) of the knee has garnered significant attention for its potential impact on postoperative kinematics and functional performance \u003csup\u003e\u003cspan additionalcitationids=\"CR7 CR8 CR9\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe JLO plays a pivotal role in maintaining alignment and distributing forces across the adjacent joints, such as the hip and ankle, during both static and dynamic activities\u003csup\u003e\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. The alignment of the knee is essential as it acts as a biomechanical coupler between the movement of the adjacent hip and ankle joint\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. This coupling mechanism has provided critical insights into movement patterns during various contexts, including stroke rehabilitation, limb malalignment in children, and certain strategies during physiotherapy\u003csup\u003e\u003cspan additionalcitationids=\"CR16 CR17\" citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. However, its significance within TKA remains largely underexplored, particularly concerning the interplay between surgical alignment techniques and functional biomechanics.\u003c/p\u003e \u003cp\u003eConventional TKA techniques such as mechanical alignment, often involve altering the native knee alignment, which can induce compensatory adaptations in adjacent joints. These adjustments may disrupt lower limb movement patterns and compromise function outcomes\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e. Specifically, the adjusted mechanical alignment (aMA) technique changes the native JLO to a perpendicular to the tibial mechanical axis. In contrast, inverse kinematic alignment (iKA) seeks to preserve the native JLO \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e, restoring knee anatomy and biomechanics more closely to native\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e, and potentially minimizing the need for compensatory adjustments in adjacent joints that might reduce the risk of disrupted lower limb mechanics and functional impairments\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eFunctional activities range from basic gait to complex movements like squats and lunges, placing distinct requirements on joint mobility and stability. The dynamic interplay between the hip, knee, and ankle joints during these tasks is critical for movement efficiency and preserving long-term joint health \u003csup\u003e\u003cspan additionalcitationids=\"CR25 CR26\" citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e\u003c/sup\u003e. Existing evidence highlights compensatory adjustments in hip and ankle mechanics following TKA\u003csup\u003e\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e,\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u003c/sup\u003e, with reduced knee joint angle being more easily managed than similar limitations at the hip\u003csup\u003e\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e\u003c/sup\u003e. However, the specific mechanisms through which alternations to the native JLO influence compensatory strategies in adjacent joints remain underexplored. While the biomechanical coupling of the hip and knee joints has been documented in some gait and rehabilitation studies, its role in the context of TKA-specific alignment changes is less understood\u003csup\u003e\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e,\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis study seeks to fill these knowledge gaps by examining the biomechanical and functional outcomes of preserving the native JLO through iKA, compared to aMA. By analyzing joint kinematics and coupling mechanics during eight functional activities in a gait laboratory setting, this research seeks to clarify how native JLO reconstruction affects hip and ankle movement, compensatory patterns, and functional performance. The findings are expected to enhance understanding of the role of knee alignment in optimizing postoperative outcomes and contribute to refining the surgical techniques and rehabilitation strategies for TKA.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipant Selection and Ethical Review\u003c/h2\u003e \u003cp\u003e\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eThis study recruited 30 patients diagnosed with advanced-stage knee osteoarthritis, characterized by persistent, severe pain unresponsive to conservative treatments. All patients underwent robotic-assisted TKA at AZ Delta Hospital, Roeselare, Belgium whose outcomes were assessed at a two-year post-surgery. Patient selection was based on a consecutive list, provided by the hospital administration, of patients who had undergone surgery two years prior. Recruitment involved contacting potential participants via telephone, explaining the study objectives, and outlining the requirements for gait laboratory analysis.\u003c/p\u003e\u003cp\u003eEnrollment continued until 15 patients from each surgical group (iKA and aMA) agreed to participate. Importantly, the outcome measures were not disclosed to the patients during the recruitment procession. A healthy control group consisting of 21 age and sex-matched volunteers was included. The exclusion criteria ruled out individuals older than 85 years or those with comorbidities that could affect balance or gait, such as previous lower limb trauma, neurologic conditions, or systemic disease. All participants provided informed consent for data and image use. The study received approval from the institutional review board, adhered to the Declaration of Helsinki guidelines, and was registered at Ethics Committee Research UZ/KU Leuven (S67874) and Belg.Regnr (B3222022001251).\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSurgical Protocol and Perioperative Management\u003c/h3\u003e\u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eA detailed description of the surgical approach, soft tissue envelop assessment, surgical steps, the preoperative and postoperative measurements, and perioperative protocol has been previously described by Winnock de Grave et al \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e,\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. The procedure employs a far medial subvastus approach, involving a two-layer incision of the medial joint capsule. Arthrotomy is performed at the far medial aspect, anterior to the medial collateral ligament. Upon reaching the medial tibia, the longitudinal (vertical) capsular incision is redirected 90\u0026deg; horizontally, parallel to the tibial plateau, extending laterally. Importantly, no soft tissues are detached from the anteromedial tibia, consistent with the principles outlined in prior studies\u003csup\u003e\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e,\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e\u003c/sup\u003e. After completing the approach, the tourniquet was deflated for the remainder of the procedure.\u003c/p\u003e \u003cp\u003eNavigation trackers were utilized to register the femur and tibia, following the robotic surgical guide \u003csup\u003e\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e\u003c/sup\u003e. The robotic system utilized computer navigation and robotically assisted instruments (Mako, Stryker, USA), the condition of the soft-tissue envelope was integrated into the robotic platform, wherein knee ligaments were tensioned in extension (at 10\u0026deg; flexion) and flexion (at 90\u0026deg; flexion with the patella in place), either manually holding the leg or utilizing ligament tensioner or spoons \u003csup\u003e\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e\u003c/sup\u003e. The prosthetics used were cemented, cruciate retaining Triathlon TKA implant (Stryker, Kalamazoo, USA) including patellar resurfacing in all cases.\u003c/p\u003e \u003cp\u003eaMA: The constitutional coronal limb deformity was corrected within \u0026plusmn;\u0026thinsp;3\u0026deg;, with tibial resection perpendicular to the tibial mechanical axis \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec \u003cb\u003ed).\u003c/b\u003e The tibial slope matched the native medial tibial slope, and the femoral component's position was adjusted to balance the flexion gap. Soft tissue release was performed if the hip-knee-ankle (HKA) angle fell outside 177\u0026deg; to 183\u0026deg; \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e. A residual laxity of 1\u0026ndash;2 mm in both compartments in flexion and extension was targeted.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eiKA: The native tibial joint line was restored by resecting equal amounts of medial and lateral tibial bone \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ea \u003cb\u003eb).\u003c/b\u003e The tibial slope matched the native medial tibial slope, and the femoral component's position aimed to restore the medial joint line height in extension. Soft tissue release may be performed for the HKA outside 174\u0026deg; to 183\u0026deg; \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Residual laxity goals were 1\u0026ndash;2 mm in flexion and extension, with up to 3 mm allowed flexion on the lateral side.\u003c/p\u003e\n\u003ch3\u003eData Collection and Data Preprocessing\u003c/h3\u003e\n\u003cp\u003eBiomechanical data were collected at the 3D movement laboratory located on the KU Leuven Brugge campus, which is equipped with 12 Vicon Vero cameras, 2 Vicon Vue cameras, Vicon Nexus 2.12 Software (\u0026copy;Vicon Motion Systems Ltd., Oxford, UK). A blinded investigator performed the participant measurements, including weight, height, leg length, knee width, ankle width, shoulder offset, elbow width, wrist width, and hand thickness, which were entered into the Vicon system. The model then calculated parameters such as tibial torsion, thigh rotation offset, shank rotation offset, foot plantar flexion offset, foot rotation offset, and Asis-trochanter distance. The maximum joint angle was manually measured using a protractor\u003csup\u003e\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e\u003c/sup\u003e.\u003cdiv class=\"BlockQuote\"\u003e\u003cp\u003eA total of 39 reflective markers (14 mm in diameter) were placed on anatomical landmarks according to the full-body plug-in-gait model\u003csup\u003e\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e,\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e\u003c/sup\u003e. During the preparation of the participants, the Vicon system was warmed and calibration according to the instructions, trajectory tails were set to 100 frames per second. The participants kept a T-pose or 'motorbike' pose for a few seconds captured a static trial, reconstructed the trail, and created a labeling skeleton template file for the subject. View the subject data in a 3D perspective view and ensure that all markers are visible to the Vicon cameras. Run the plug-in Gait static pipeline and ensure that plug-in Gait bones (segments) are visible in the 3D perspective view. The hip joint center was determined using the functional method, where markers placed on the pelvis and thigh were used to estimate the center of rotation during dynamic movements. No knee alignment device was used for the knee or ankle joint centers. The knee joint center is determined using the modified chord function, from the global position of the hip joint center, the thigh wand marker, and the knee maker, together with the knee offset, and thigh wand angle offset from the subject measurements. The ankle joint center is calculated from the knee joint center, shank cand marker, and ankle maker with the ankle offset and shank rotation offset using the modified chord function.\u003c/p\u003e\u003cp\u003eThe participants were instructed to perform eight functional activities \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e:\u003c/p\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003col\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eGait \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ea-e\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eLunge \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ep-r\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eSquat \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003es-u\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eLow step-up (165mm) \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ef-h\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eHigh step-up (280 mm) \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ek-m\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eLow step-down (165 mm) \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eh-j\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eHigh step-down (280 mm) \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003em-o\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003cspan\u003e \u003cli\u003e \u003cp\u003eFive times sit-to-stand from a chair (460 mm high) \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003ev-x\u003cb\u003e)\u003c/b\u003e\u003c/p\u003e \u003c/li\u003e \u003c/span\u003e \u003c/ol\u003e \u003c/p\u003e \u003cp\u003eEach activity was performed three times at a self-selected speed, the collected data underwent processing steps including reconstruction, filtering (Woltring filter), labeling, gap filling, events creation (where event names were assigned based on the motion of the knee marker as illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), cycle definition, dynamic Plug-in Gait model analysis, and calculation of cycle parameters. The trials were saved in the C3D\u0026thinsp;+\u0026thinsp;VSK format and exported to C3D.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe output angles for all joints are calculated from the YXZ cardan angles derived by comparing the relative orientation of the segments proximal (parent) and distal (child) to the joint\u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. Hip Flexion/Extension: Hip flexion is calculated about an axis parallel to the pelvic transverse axis which passes through the hip joint center. The sagittal thigh axis is projected onto the plane perpendicular to the hip flexion axis. Hip flexion is then the angle between the projected sagittal thigh axis and the sagittal pelvic axis. A positive (Flexion) angle value corresponds to the situation in which the knee is in front of the body \u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e. Knee Flexion/Extension: The sagittal shank axis is projected into the plane perpendicular to the knee flexion axis. Knee flexion is the angle in that plane between this projection and the sagittal thigh axis. The sign is such that a positive angle corresponds to a flexed knee. Ankle Dorsi/Plantar Flexion: The foot vector is projected into the foot sagittal plane. The angle between the foot vector and the sagittal axis of the shank is the foot dorsi/plantar. A positive number corresponds to dorsiflexion \u003csup\u003e\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe movement of eight functional activities was divided into two temporal phases: (1) Forward phase, from movement initiation to maximum knee flexion, and (2) Balance phase, from maximum knee flexion to the knee extension \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. For gait, the movement was initially divided into stance phase \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea-c\u003cb\u003e)\u003c/b\u003e and swing phase \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec-e\u003cb\u003e)\u003c/b\u003e \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e, and then further separated into the forward \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea-b, c-d\u003cb\u003e)\u003c/b\u003e and balance phase \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb-c, d-e\u003cb\u003e)\u003c/b\u003e, and for five-times sit-to-stand from a chair initially divided into one cycle (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ev-x), sit-down equals forward phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ev-w), stand-up equals balance phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ew-x). The forward phases were depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e \u003cb\u003eas a-b, c-d, f-g, h-i, k-l, m-n, p-q, s-t, and v-w.\u003c/b\u003e While the balance phases were represented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e \u003cb\u003eas b-c, d-e, g-h, i-j, l-m, n-o, q-r, t-u, and w-x.\u003c/b\u003e\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe sample size was determined based on previous studies by De Vroey et al and McClelland\u003csup\u003e\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e,\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e\u003c/sup\u003e. Upon completion of data collection, the effect size was calculated to verify that the sample of 15 participants was sufficient for the study. The data was then exported to MATLAB (R2022b for Windows; The MathWorks, Inc, Natick, MA, USA) for further analysis. All discrete measures were evaluated for normality and homogeneity of variance before statistical analysis. A one-way ANOVA, followed by \u003cem\u003epost hoc t\u003c/em\u003e-tests with Bonferroni-adjusted, was employed for comparisons involving variables, such as sex, age, height, weight, body mass index (BMI), leg length, and maximum joint angles. Additionally, \u003cem\u003et\u003c/em\u003e-tests were used to compare postoperative time, operative leg, preoperative HKA, and postoperative HKA. A significance threshold of \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was applied for the analysis. The statistical parametric mapping (Version 0.4.10, \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ewww.spm1d.org\u003c/span\u003e\u003cspan address=\"http://www.spm1d.org\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e) one-way ANOVA was used to compare results among the three groups of the kinematic mean joint angler, followed by \u003cem\u003epost hoc\u003c/em\u003e multiple \u003cem\u003et\u003c/em\u003e-tests with Bonferroni-adjusted critical \u003cem\u003ep\u003c/em\u003e-value to identify specific differences between group pairs. The trendline R-squared (R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e) value was used to assess the relationship between the hip, knee, and ankle joint angles, and then segment the joint angle ranges for each activity.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eDemographics and Clinical Characteristics\u003c/h2\u003e \u003cp\u003eThe mean age was 72.93\u0026thinsp;\u0026plusmn;\u0026thinsp;6.09 years in the iKA group, 65.00\u0026thinsp;\u0026plusmn;\u0026thinsp;8.10 years in the aMA group, and 67.48\u0026thinsp;\u0026plusmn;\u0026thinsp;7.54 years in the healthy control group. The iKA group had a mean weight of 88.30\u0026thinsp;\u0026plusmn;\u0026thinsp;14.80 kg, the aMA group had a mean weight of 92.90\u0026thinsp;\u0026plusmn;\u0026thinsp;10.00 kg, and the healthy control group had a mean weight of 76.70\u0026thinsp;\u0026plusmn;\u0026thinsp;9.20 kg. No significant differences were found among the three groups for height (F (2, 48)\u0026thinsp;=\u0026thinsp;0.25, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.779), BMI (F (2, 48)\u0026thinsp;=\u0026thinsp;0.07, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.933), or leg length (right leg: F (2, 48)\u0026thinsp;=\u0026thinsp;1.16, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.321; left leg: F (2, 48)\u0026thinsp;=\u0026thinsp;1.15, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.326). No significant differences were observed in preoperative HKA alignment. Postoperative HKA alignment showed significant differences (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.006), with the iKA group (-1.72\u0026deg; \u0026plusmn; 2.04\u0026deg;) exhibiting less neutral alignment compared to the aMA (0.05\u0026deg; \u0026plusmn; 1.54\u0026deg;). The demographics and clinical characteristics of participants across study groups are displayed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Four participants in the aMA group were unable to complete the high step-up and high step-down tasks, while two participants in the iKA group could not perform these tasks. Additionally, one participant in the healthy control group was excluded from the functional activities analysis due to issues with Vicon system calibration.\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 and clinical characteristics of participants across study groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"10\"\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=\"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=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" 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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eiKA (\u003cem\u003en\u0026thinsp;=\u0026thinsp;15 )\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eaMA (\u003cem\u003en\u0026thinsp;=\u0026thinsp;15)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eHC (\u003cem\u003en\u0026thinsp;=\u0026thinsp;21)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eANOVA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c10\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003ePost hoc (t-tests)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003emean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026plusmn; SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003emean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026plusmn; SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003emean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u0026plusmn; SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex (m/f)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10/5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9/6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e12/9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.852\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (year)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e72.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e65.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e8.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e67.48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e7.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e4.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eA: 0.005; B: 0.027.; C:0.353\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeg length Right (m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.321\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLeg length Left (m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.326\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight (m)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.779\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight (kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e88.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e92.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e76.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e9.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e15.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.000\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eA: \u003cem\u003e0.329\u003c/em\u003e; B:\u0026lt;0.001; C:0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e33.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e27.30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e3.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e0.933\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePostop (months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e21.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24.40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.171\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOperated leg (left/right)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8/11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9/8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.529\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHKA preop (\u0026deg;, - varus)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-3.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e4.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.500\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHKA postop (\u0026deg;, - varus)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1.54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0.006\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"10\"\u003e\u003cem\u003eNote.\u003c/em\u003e iKA\u0026thinsp;=\u0026thinsp;inverse kinematic alignment total knee arthroplasty; aMA\u0026thinsp;=\u0026thinsp;adjusted mechanical alignment total knee arthroplasty; HC\u0026thinsp;=\u0026thinsp;healthy control; BMI\u0026thinsp;=\u0026thinsp;body mass index; SD\u0026thinsp;=\u0026thinsp;standard deviation; n: number; m/f: male/female; m: meter; kg: kilogram; (\u0026deg;)\u0026thinsp;=\u0026thinsp;degree; ANOVA: One-way analysis of variance; F: F-statistic derived from one-way analysis of variance; P : \u003cem\u003ep\u003c/em\u003e-value from one-way analysis of variance; statistical significance was set at \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, bold values indicate a significant difference between groups; A:significant difference between iKA and aMA; B: significant difference between iKA and HC; C: significant difference between aMA and HC. N/A: Not Applicable.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eClinical Examination of Maximum Joint Angle\u003c/h3\u003e\n\u003cp\u003eThe maximum joint angles of the hip, knee, and ankle, as manually measured using a protractor, are presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. Hip flexion angles were 111.11\u0026deg; \u0026plusmn; 12.05\u0026deg; in the iKA group, 102.06\u0026deg; \u0026plusmn; 23.10\u0026deg; in the aMA group, and 113.33\u0026deg; \u0026plusmn; 11.08\u0026deg; in the healthy control group. Statistical analysis revealed a significant difference across the three groups (F (2, 75)\u0026thinsp;=\u0026thinsp;3.60, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.032), with \u003cem\u003epost hoc\u003c/em\u003e comparisons indicating a significant difference between the aMA and healthy control group (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014). Similarly, the hip extension was recorded as 11.26\u0026deg; \u0026plusmn; 4.94\u0026deg; in the iKA group, 9.44\u0026deg; \u0026plusmn; 5.02\u0026deg; in the aMA group, and 13.24\u0026deg; \u0026plusmn; 5.01\u0026deg; in the healthy control group, with a significant overall group effect (F (2, 75)\u0026thinsp;=\u0026thinsp;4.91, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.010), \u003cem\u003epost hoc\u003c/em\u003e analysis revealed a significance difference between the aMA and healthy control groups (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.003). In contrast, no significant differences were observed for knee extension across the groups. However, knee flexion values were significantly different among the groups, with the iKA group showing 120.47\u0026deg; \u0026plusmn; 7.65\u0026deg;, the aMA group showing 109.59\u0026deg; \u0026plusmn; 18.28\u0026deg;, and the healthy control group showing 136.21\u0026deg; \u0026plusmn; 9.37\u0026deg;. The iKA and aMA groups exhibited significantly reduced knee flexion compared to the healthy control group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). No significant differences were detected in the ankle joint angles.\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\u003eManual measurement of hip, knee, and ankle maximum joint angles using a protractor.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"13\"\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 \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e \u003cp\u003eiKA (\u003cem\u003en\u0026thinsp;=\u0026thinsp;19)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e \u003cp\u003eaMA (\u003cem\u003en\u0026thinsp;=\u0026thinsp;17)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"3\" nameend=\"c10\" namest=\"c8\"\u003e \u003cp\u003eHC (\u003cem\u003en\u0026thinsp;=\u0026thinsp;42)\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c12\" namest=\"c11\"\u003e \u003cp\u003eANOVA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c13\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cem\u003ePost hoc\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003emean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026plusmn;SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMin\u0026thinsp;~\u0026thinsp;Max\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003emean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026plusmn; SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eMin\u0026thinsp;~\u0026thinsp;Max\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003emean\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c9\"\u003e \u003cp\u003e\u0026plusmn; SD\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c10\"\u003e \u003cp\u003eMin\u0026thinsp;~\u0026thinsp;Max\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c11\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c12\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHip flexion (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e111.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e12.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80\u0026thinsp;~\u0026thinsp;125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e102.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e23.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e21\u0026thinsp;~\u0026thinsp;125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e113.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e11.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e91\u0026thinsp;~\u0026thinsp;144\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e3.60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.032\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eA:0.144; B: 0.482; \u003cb\u003eC;0.014\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHip extension (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e11.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u0026thinsp;~\u0026thinsp;20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e9.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e5.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u0026thinsp;~\u0026thinsp;15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e13.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e5.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e4\u0026thinsp;~\u0026thinsp;22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e4.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.010\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eA:0.151; B: 0.158; C; \u003cb\u003e0.003\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHip Abduction (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e36.26\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9\u0026thinsp;~\u0026thinsp;50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e37.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e15\u0026thinsp;~\u0026thinsp;50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e39.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e9.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e25\u0026thinsp;~\u0026thinsp;68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e1.07\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.347\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHip adduction (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e17.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7\u0026thinsp;~\u0026thinsp;25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e18.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e8\u0026thinsp;~\u0026thinsp;29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e20.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e4.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e8\u0026thinsp;~\u0026thinsp;30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e3.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.031\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eA:0.606; \u003cb\u003eB:0.009\u003c/b\u003e; C; 0.093\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHip extern rotation (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e29.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e9.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15\u0026thinsp;~\u0026thinsp;49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e34.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e8.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e15\u0026thinsp;~\u0026thinsp;45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e33.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e9.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e12\u0026thinsp;~\u0026thinsp;50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e1.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.297\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHip internal rotation (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21.95\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e5.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14\u0026thinsp;~\u0026thinsp;30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e24.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e6.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e12\u0026thinsp;~\u0026thinsp;37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e27.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e9.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e10\u0026thinsp;~\u0026thinsp;48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e3.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.029\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eA:0.023; B: 0.015; C; \u003cb\u003e0.015\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee extension (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e2.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e2.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u0026thinsp;~\u0026thinsp;7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e3.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e2.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u0026thinsp;~\u0026thinsp;8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e1.72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e3.70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e-12\u0026thinsp;~\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.880\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eKnee flexion (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e120.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e7.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e80\u0026thinsp;~\u0026thinsp;130\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e109.59\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e18.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e70\u0026thinsp;~\u0026thinsp;135\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e136.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e9.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e118\u0026thinsp;~\u0026thinsp;160\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e36.68\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 \u003cp\u003eA: 0.698; \u003cb\u003eB: \u0026lt;0.001; C:\u0026lt;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle dorsiflexion 0\u0026deg; (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e11.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e11.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-10\u0026thinsp;~\u0026thinsp;40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e7.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e4.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u0026thinsp;~\u0026thinsp;20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e11.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e5.67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e0\u0026thinsp;~\u0026thinsp;23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e1.62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.204\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle plantarflexion (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e44.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e14.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15\u0026thinsp;~\u0026thinsp;60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e41.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e11.80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e24\u0026thinsp;~\u0026thinsp;60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e45.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e13.73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e19\u0026thinsp;~\u0026thinsp;70\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.602\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAnkle dorsiflexion 90\u0026deg; (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e18.21\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e6.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u0026thinsp;~\u0026thinsp;30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e19.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e9.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u0026thinsp;~\u0026thinsp;35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e16.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e6.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e2\u0026thinsp;~\u0026thinsp;29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e1.19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.310\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePopliteal angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e33.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e10.86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19\u0026thinsp;~\u0026thinsp;60\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e31.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e15.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u0026thinsp;~\u0026thinsp;55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e31.38\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e \u003cp\u003e12.90\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c10\"\u003e \u003cp\u003e10\u0026thinsp;~\u0026thinsp;62\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c11\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c12\"\u003e \u003cp\u003e0.784\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c13\"\u003e \u003cp\u003eN/A\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"13\"\u003e\u003cem\u003eNote.\u003c/em\u003e iKA\u0026thinsp;=\u0026thinsp;inverse kinematic alignment total knee arthroplasty; aMA\u0026thinsp;=\u0026thinsp;adjusted mechanical alignment total knee arthroplasty; HC\u0026thinsp;=\u0026thinsp;healthy control; (\u0026deg;)\u0026thinsp;=\u0026thinsp;degree; SD\u0026thinsp;=\u0026thinsp;standard deviation; n: number; ANOVA: One-way analysis of variance; F: F-statistic derived from one-way analysis of variance; P: \u003cem\u003ep\u003c/em\u003e-value from one-way analysis of variance; statistical significance was set at \u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.05, bold values indicate a significant difference between groups; A:significant difference between iKA and aMA; B: significant difference between iKA and HC; C: significant difference between aMA and HC. N/A: Not Applicable.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eCoupled Movement Between Hip and Knee\u003c/h3\u003e\n\u003cp\u003eThe coupled movement of the hip and knee during the forward phase of the eight activities is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Both the iKA and aMA groups displayed slightly lower R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e values compared to the healthy control group while maintaining a consistent relationship with the healthy control group when the knee flexion is below 110\u0026deg; and hip flexion less than 100\u0026deg;, as observed during gait, low step-down, high step-down, low step-up, and sit-down (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea-f). When the knee flexion exceeded 110\u0026deg; and the hip flexion remained below 100\u0026deg;, the aMA group maintained a similar R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e value to the healthy control group (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eg). However, one-way ANOVA and \u003cem\u003epost hoc\u003c/em\u003e revealed a significant difference in hip joint angles between the aMA and healthy control groups during the high step-up activity (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec \u003cb\u003e\u0026amp;\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ed), while no significant difference between the iKA and healthy control groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec \u0026amp; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ee). Furthermore, when the knee flexion exceeded 110\u0026deg; and the hip flexion surpassed 100\u0026deg;, the R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e value and hip joint angle for the aMA group significant difference from that of the healthy control group. However, there were no significant differences between the iKA and healthy control groups. This was particularly evident during the lunge and squat activities \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eh, i\u003cb\u003e)\u003c/b\u003e, specifically, during the lunge, the R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e values for the aMA group decreased to 0.160 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), compared to values of 0.731 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.013) and 0.611 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001) for the iKA and healthy control groups, respectively \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eh\u003cb\u003e).\u003c/b\u003e During the squat, the R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e value for the aMA group was 0.292 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;\u0026lt;\u0026thinsp;0.001), while the values for the iKA and healthy control groups were 0.741 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.058) and 0.805 (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.321), respectively \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ei\u003cb\u003e).\u003c/b\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eHip Flexion Angles During Step-up.\u003c/b\u003e \u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e illustrates that the hip flexion in the low step-up task of a significant difference among the three groups between 0% and 11%, as well as between 23% and 33% of the low step-up phase (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea \u003cb\u003eb\u003c/b\u003e; +8.93, F (2, 62)\u0026thinsp;=\u0026thinsp;5.95, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.016 \u0026amp; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.018). However, during the high step-up, a significant difference in hip flexion among the three groups between 0% and 30%, and between 89% and 100% (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec \u003cb\u003ed\u003c/b\u003e; +11.45, F (2, 56)\u0026thinsp;=\u0026thinsp;5.21, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004 \u0026amp; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.038). The results of the \u003cem\u003epost hoc\u003c/em\u003e analysis are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e, which further confirms significant differences between the aMA and healthy control groups during high step-up (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea; \u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.15, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005 \u0026amp; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.016), and the \u003cem\u003epost hoc\u003c/em\u003e multiple \u003cem\u003et\u003c/em\u003e-tests with Bonferroni-adjusted critical \u003cem\u003ep\u003c/em\u003e-value: α\u0026thinsp;=\u0026thinsp;0.017, whereas no significant difference was observed between iKA and healthy control groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eb).\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eAnkle Flexion During Functional Activities\u003c/h2\u003e \u003cp\u003eThe ankle angle results of one-way ANOVA and mean comparisons during low step-down and gait cycles are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e. There is significantly reduced ankle plantarflexion compared to the healthy control group between 44% and 48% of the low step-down (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea \u003cb\u003eb\u003c/b\u003e; -4\u0026ordm;, F (2, 62)\u0026thinsp;=\u0026thinsp;6.82, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.035). This difference was confirmed by \u003cem\u003epost hoc\u003c/em\u003e analysis between the aMA and healthy control groups (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea; \u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.68, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008). No significant differences were observed for the iKA group during this phase. Furthermore, during the gait cycle, there was exhibited significantly different ankle plantarflexion among the three groups between 50% and 70%, as well as between 84% and 97% of the gait cycle (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ec \u003cb\u003ed\u003c/b\u003e; -7.41\u0026ordm;, F (2, 63)\u0026thinsp;=\u0026thinsp;6.08, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.007 and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.021, respectively). \u003cem\u003ePost hoc\u003c/em\u003e analysis further revealed that the aMA group exhibited significantly reduced plantarflexion compared to the HC group (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ed; t\u0026thinsp;=\u0026thinsp;3.38, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002). Additionally, the iKA group displayed significant differences compared to the aMA group (Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ef; \u003cem\u003et\u003c/em\u003e\u0026thinsp;=\u0026thinsp;3.40, \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.006 \u0026amp; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.004).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study investigates the impact of the restoration of the native JLO on functional activities following TKA. Our findings demonstrate that preserving the native JLO effectively maintains the natural joint kinematics between the hip, knee, and ankle, enabling physiologically accurate movement patterns. The effect of JLO preservation particularly becomes evident in activities requiring extreme joint angles, such as high step-up, lunge, and squat, where hip movement more closely resembles natural biomechanics with iKA, compared to aMA. Additionally, during gait and low step-down activities, the ankle plantarflexion angle in the iKA group closely approximates that of the HC group, underscoring the biomechanical advantage of retaining the native JLO.\u003c/p\u003e \u003cp\u003eThe coupled movement between the hip and knee refers to their interdependent motion, wherein the movement at one joint directly influences and affects the movement at the other joint\u003csup\u003e\u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e\u003c/sup\u003e. This interdependence arises from shared muscle groups and the bony alignment of the lower limb, which together facilitate coordinated movement patterns\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e,\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e\u003c/sup\u003e. This study provides the first comprehensive examination of this relationship across multiple functional activities within the TKA domain. During activities requiring knee flexion angles no more than 110 degrees and hip flexion angles no more than 100 degrees, such as gait, low step-down, high step-down, sit-to-stand, low step-up, both the aMA and iKA groups exhibited R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e values comparable to each other, though slightly lower than those of the HC group \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003ea-f\u003cb\u003e)\u003c/b\u003e.\u003c/p\u003e \u003cp\u003eIn activities requiring knee flexion angle exceeding 110 degrees and hip flexion angles no more than 100 degrees, such as high step-up, the R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e values for the aMA and iKA groups remained closely aligned with those of the HC group (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eg). However, during high step-up activities, which approaches the maximum knee flexion threshold of the aMA group (109.59\u0026ordm; \u0026plusmn; 18.28\u0026ordm;; Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e, the aMA group required significantly greater hip flexion angles to complete the movement \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ec \u003cb\u003ed\u003c/b\u003e \u0026amp; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003ea\u003cb\u003e).\u003c/b\u003e This pattern is consistent with previous research indicating altered movement patterns in TKA patients during functional activities\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e,\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e,\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e,\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e\u003c/sup\u003e. When the prosthetic knee flexion angle is restricted, compensatory adjustments in the hip motion are required to meet functional demands\u003csup\u003e\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e\u003c/sup\u003e. Notably, four participants in the aMA group were unable to complete this task due to its biomechanical demands.\u003c/p\u003e \u003cp\u003eDuring activities requiring knee flexion angles surpassing 110 degrees and hip flexion angles exceeding 100 degrees, such as lunge and squat, the iKA group demonstrated hip flexion angles and R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e values closely aligned with those of the HC group. In contrast, the aMA group showed significant deviations from the HC group \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eh, i\u003cb\u003e)\u003c/b\u003e, reaching or exceeding the aMA group\u0026rsquo;s maximum knee and hip flexion thresholds. The maximum hip flexion of the aMA group (102.06\u0026ordm; \u0026plusmn; 23.10\u0026ordm;) is significantly lower than the HC group (113.33\u0026ordm; \u0026plusmn; 11.08\u0026ordm;; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). These deviations may be attributed to alternations in femoral neck anteversion, defined as the angle between the femoral neck and shaft, which plays a crucial role in influencing hip biomechanics\u003csup\u003e\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e\u003c/sup\u003e. Although dynamic changes in femoral neck anteversion following total hip arthroplasty have been extensively documented\u003csup\u003e\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e\u003c/sup\u003e, its alterations post-TKA remain insufficiently explored. In varus knees treated with the aMA technique, the medial posterior condyle is typically resected 2\u0026ndash;4 mm thicker than the lateral posterior condyle\u003csup\u003e\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e,\u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e\u003c/sup\u003e, leading to modifications in femoral neck anteversion \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ed, f\u003cb\u003e)\u003c/b\u003e. Such changes may restrict hip flexion angles during demanding tasks, such as lunge and squat \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eh, i\u003cb\u003e).\u003c/b\u003e Additionally, a decrease in the femoral abduction angle may modestly affect the effectiveness of the aMA group in these activities \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec, e\u003cb\u003e)\u003c/b\u003e. In contrast, the iKA technique preserves the native distal femoral anatomy, maintaining a more natural femoral neck anteversion (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eb, f), which contributes to R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e values and mean hip joint angles comparable to those of the HC group during these activities \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eh, i\u003cb\u003e)\u003c/b\u003e. The maximum hip flexion observed in the iKA group (111.11\u0026ordm; \u0026plusmn; 12.05\u0026ordm;) compared to the HC group (113.33\u0026ordm; \u0026plusmn; 11.08\u0026ordm;; \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.482) further supports this finding (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eOur results also reveal that during gait and low step-down activities, the plantarflexion ankle angle in the aMA group significantly differs from that of the HC group \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea-d \u0026amp; Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003ea \u003cb\u003ed)\u003c/b\u003e. Conversely, the iKA group exhibits ankle plantarflexion angles closely approximating those of the HC group (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003ea-d \u003cb\u003e\u0026amp;\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003eb \u003cb\u003ee\u003c/b\u003e). Previous research has shown that perpendicular cuts to the tibial mechanical axis lead to alterations in the alignment of the ankle joint line, which is consistent with our findings\u003csup\u003e\u003cspan additionalcitationids=\"CR52\" citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e\u003c/sup\u003e. Restoration of the native JLO is crucial for preserving not only knee biomechanics but also the natural alignment and function of the ankle\u003csup\u003e\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e\u003c/sup\u003e. When the native JLO is altered to 90 degrees in the aMA approach \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003ec \u003cb\u003ed)\u003c/b\u003e, even a small angular change at the knee can translate through the tibia to produce a significantly exaggerated angular change at the ankle, particularly in activities requiring plantarflexion, such as gait and low step-down \u003cb\u003e(\u003c/b\u003eFig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e \u003cb\u003e\u0026amp;\u003c/b\u003e Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. This may also explain previous findings that foot orientation during gait differs from natural patterns after mechanical alignment TKA\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e,\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis study has several limitations. While sagittal plane movements were recorded accurately using the Vicon system, measurements in the coronal and transverse planes were less accurate. A more comprehensive evaluation of these planes would provide possibly more insights into the movements post-TKA. Although weight differences were normalized within the Vicon system, they may have been influenced by the kinetic aspects of the data from the forces plane, as a result, kinetic data were excluded from this analysis. Future studies incorporating comparable kinetic data would enhance the depth of these findings. Additionally, although electromyography data on muscle activity was collected, they were not analyzed in this study as they fall outside the scope of kinematic analysis. Incorporating these data in future studies could enhance our understanding of muscle behavior during post-TKA functional activities.\u003c/p\u003e \u003cp\u003eIn conclusion, the rising prevalence of TKA underscores the importance of addressing its long-term biomechanical implications. Changes in knee alignment significantly influence not only the knee but also the hip and ankle, emphasizing the importance of considering whole-limb biomechanics. By preserving the native JLO, it is possible to achieve postoperative movement patterns more closely aligned with natural kinematics, ultimately improving functional outcomes and quality of life for TKA patients.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Van Criekinge Tamaya, Winnock deGrave Philip, Luyckx Thomas, Claeys Kurt, and Li Zhijun. The first draft of the manuscript was written by Li Zhijun. Winnock de Grave Philip, Claeys Kurt commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eWe sincerely thank the staff at AZ Delta, Roeselare, Belgium, for their invaluable assistance. We would also like to express our gratitude to the Rehabilitation Sciences team at KU Leuven, Brugge, Belgium, for their continued support. We extend our appreciation to the dedicated researchers at the Bioengineering Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, USA, for their contributions to help understand the data.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe dataset of this study is not publicly available due to the ongoing nature of this 15-year project. At this stage, the raw data can not be shared or utilized; however, data accessibility will be periodically reviewed, and we will ensure compliance with ethical and regulatory guidelines as the project progresses. Data may be available from the corresponding author upon request, subject to approval by the ethics committees of KU Leuven University and AZ Hospital.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKrummenauer, A., C. Wolf, K.-P. G\u0026uuml;nther \u0026amp; S. Kirschner. Clinical benefit and cost-effectiveness of total knee arthroplasty in the older patient. \u003cem\u003eEur. J. Med. Res.\u003c/em\u003e \u003cstrong\u003e14\u003c/strong\u003e, 76\u0026ndash;84 (2009).\u003c/li\u003e\n\u003cli\u003eKurtz, S., Ong, K., Lau, E., Mowat, F. \u0026amp; Halpern, M. Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. \u003cem\u003eJ. Bone Jt. Surg.\u003c/em\u003e \u003cstrong\u003e89\u003c/strong\u003e, 780\u0026ndash;785 (2007).\u003c/li\u003e\n\u003cli\u003eBeringer, D. C., Patel, J. J. \u0026amp; Bozic, K. J. An overview of economic issues in computer-assisted total joint arthroplasty. \u003cem\u003eClin. 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Radiologic changes of the ankle joint after total knee arthroplasty. \u003cem\u003eFoot Ankle Int.\u003c/em\u003e \u003cstrong\u003e33\u003c/strong\u003e, 1087\u0026ndash;1092 (2012).\u003c/li\u003e\n\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":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Total knee arthroplasty, Alignment, Joint line obliquity, functional activities, couple of movement","lastPublishedDoi":"10.21203/rs.3.rs-6147433/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6147433/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePreserving the native joint line obliquity (JLO) during total knee arthroplasty (TKA) may enhance postoperative function. This study compared inverse kinematic alignment (iKA) TKA, which preserves native JLO, with adjusted mechanical alignment (aMA) TKA, which standardizes JLO to 90\u0026deg;, and a healthy control group across eight functional activities. Both TKA groups exhibited hip-knee coupling patterns similar to healthy controls during gait, low step-down, high step-down, low step-up, and sit-down activities. However, the aMA group required significantly greater compensatory hip flexion during high step-up (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.005, 0.016; Bonferroni-adjusted α\u0026thinsp;=\u0026thinsp;0.017), despite demonstrating a lower maximum hip flexion (102.6\u0026deg; \u0026plusmn; 23.10\u0026ordm;) compared to the healthy control group (113.33\u0026deg; \u0026plusmn; 11.08\u0026ordm;) (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.014). In contrast, the iKA group maintained hip-knee coupling patterns comparable to the healthy control group during more demanding activities, such as lunges and squats. Additionally, the aMA group exhibited reduced ankle plantarflexion compared to the healthy control group during low step-down (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.008) and gait (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002), while the iKA group was more closely with the healthy control group. Preserving native JLO supports natural hip and ankle motion, particularly under extreme joint angles, emphasizing the need to address TKA-induced biomechanical adaptations to improve functional outcomes.\u003c/p\u003e","manuscriptTitle":"Restoration of the Native Joint Line Obliquity in Total Knee Arthroplasty Benefits Hip and Ankle Function","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-21 11:25:45","doi":"10.21203/rs.3.rs-6147433/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-06-10T07:21:16+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-06-09T12:49:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"281968547296963991030458144684860539016","date":"2025-05-19T15:38:44+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-09T15:06:36+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"148012787010445353807728531013268258951","date":"2025-03-31T14:32:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"190849966525742440850905177701763178915","date":"2025-03-31T14:15:13+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-31T14:00:24+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-03-31T13:57:38+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-03-19T04:22:41+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-17T08:29:12+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2025-03-03T15:02:30+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9f047909-4067-4534-990c-322971958a32","owner":[],"postedDate":"April 21st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":47445546,"name":"Health sciences/Diseases/Rheumatic diseases/Osteoarthritis"},{"id":47445547,"name":"Health sciences/Health occupations/Orthopaedics"}],"tags":[],"updatedAt":"2025-07-28T07:23:53+00:00","versionOfRecord":[],"versionCreatedAt":"2025-04-21 11:25:45","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6147433","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6147433","identity":"rs-6147433","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}