Three-dimensional lower limb kinematics and kinetics in femoroacetabular impingement syndrome (FAIS) patients with and without borderline developmental dysplasia of the hip (BDDH) during level walking

Three-dimensional lower limb kinematics and kinetics in femoroacetabular impingement syndrome (FAIS) patients with and without borderline developmental dysplasia of the hip (BDDH) during level walking | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Three-dimensional lower limb kinematics and kinetics in femoroacetabular impingement syndrome (FAIS) patients with and without borderline developmental dysplasia of the hip (BDDH) during level walking Yuang Hao, Shuang Ren, Yichuan Zhu, Tong-Chuan He, Xin Miao, Yan Xu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5843084/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 May, 2025 Read the published version in BMC Musculoskeletal Disorders → Version 1 posted 4 You are reading this latest preprint version Abstract Purpose The impact of femoroacetabular impingement syndrome (FAIS) on gait has been reported; however, no studies have documented the effects of Borderline Developmental Dysplasia of the Hip (BDDH) combined with FAIS on gait. This study aimed to evaluate the kinematic and kinetic abnormalities of the lower extremities in patients with combined FAIS and BDDH during level walking. Methods A total of 42 participants were included, consisting of 14 patients with FAIS + BDDH, 14 with isolated FAIS and 14 healthy controls. Full-cycle kinematic and kinetic data were collected via motion capture and force plates. Gait analysis was performed in three planes (sagittal, coronal and transverse) for the hip, knee, ankle and pelvis joints. The range of motion (ROM), kinematics and kinetics were compared across the three groups. Results Compared with isolated FAIS patients, FAIS + BDDH patients presented a significantly greater hip flexion angle during terminal stance and significantly smaller hip extension angles during preswing (P < 0.05). Moreover, the hip abduction moment was significantly reduced in the loading response and midstance phases in FAIS + BDDH patients (P < 0.05). The knee extension moment was significantly reduced during terminal stance in both FAIS groups (P < 0.05). The ankle dorsiflexion angle was significantly greater during midstance in FAIS + BDDH patients than in healthy controls, with concomitant reductions in the ankle dorsiflexion moment (P 0.05). Conclusion Compared with patients with isolated FAIS, patients with FAIS combined with BDDH exhibit a gait pattern characterized by biomechanical defects of the hip joint similar to developmental dysplasia of the hip (DDH), increased knee stiffness, and compensatory alterations in the ankle joint. Level of evidence: V. Femoroacetabular impingement syndrome Biomechanics Gait Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Background Femoroacetabular impingement syndrome (FAIS) is a morphological abnormality of the hip joint that is commonly observed in young and active adults[1–3]. In a healthy hip joint, sufficient femoral head‒neck offset helps prevent impingement between the femoral neck and the pelvis. Surgical intervention is a commonly employed treatment for FAIS. Existing evidence demonstrates that, in the short term, surgical procedures can lead to significant improvements in joint function and a reduction in pain, thereby enhancing overall clinical outcomes[1, 4]. Borderline developmental dysplasia of the hip (BDDH) refers to a condition falling between a normal hip and adult developmental dysplasia of the hip (DDH)[5]. BDDH is typically defined as an acetabular lateral center-edge angle (LCEA) between 18 and 25 degrees[6, 7]. Furthermore, BDDH combined with hip joint instability is more likely to result in failure during arthroscopic treatment[8]. BDDH has gained considerable clinical attention in recent years[9]. A systematic review reported that the failure rate of arthroscopic surgery in FAIS patients with combined BDDH (FAI + BDDH) is 14.1% [10]. Abnormal hip morphology or movements beyond the physiological range can result in repetitive low-impact loading, particularly during combined movements in the sagittal, frontal, and transverse planes, such as hip flexion, adduction, and internal rotation[1, 3]. Previous studies have reported abnormal gait patterns in patients with DDH [11–13], with insufficient acetabular coverage identified as a primary reason contributing to these abnormalities. However, the underlying reasons for poor clinical outcomes in patients with BDDH remain poorly understood. Therefore, the aim of this study was to investigate the biomechanical characteristics associated with FAI + BDDH more thoroughly, with the goal of providing more effective guidance for rehabilitation strategies and clinical interventions. Therefore, the primary purpose of this study was to identify the biomechanical alterations in the lower limbs of FAIS + BDDH patients compared with those of isolated FAI patients and healthy controls through gait analysis, with the aim of elucidating the potential impact of BDDH on patients with FAIS. We hypothesized that gait abnormalities in FAIS + BDDH patients would be more pronounced than those in isolated FAIS patients. Methods Participants After institutional review board approval, patients who underwent hip arthroscopy from March 2024 to November 2024 at our institute were selected for gait analysis. The inclusion criteria included patients who were diagnosed with FAIS on the basis of their clinical symptoms and radiographic findings[14]. The exclusion criteria were as follows: (1) previous lower limb surgery[15]; (2) concomitant hip conditions, including hip osteoarthritis (OA) with a Tönnis grade > 1, avascular necrosis, Legg-Calvé-Perthes disease, osteoid osteoma, synovial chondromatosis, pigmented villonodular synovitis, and DDH (LCEA 40°). Data collection Patient demographic characteristics, including age at surgery, sex, affected side, height, weight, body mass index (BMI) and duration of symptoms, were recorded. Radiographic examinations were performed preoperatively to obtain an alpha angle (AA) in the Dunn view, lateral center edge angle (LCEA) and Tönnis grade in the anteroposterior (AP) view, as described in previous studies[16–18]. All enrolled patients underwent preoperative MRI with a 3.0 T scanner. Fat-saturated proton density (FSPD) sequences and T2-weighted sequences were performed in the axial, coronal, and oblique sagittal planes, respectively. A previously validated, semiquantitative, MRI-based scoring system (scoring hip osteoarthritis with MRI [SHOMRI]) was used to assess abnormalities in the articular cartilage and labrum of the hip joint separately[19]. The SHOMRI system has been previously used in assessments of hip joint abnormalities in patients with hip OA[20, 21]. Self-reported outcomes Patient-reported outcomes (PROs), including the visual analog pain scale (VAS), modified Harris hip score (mHHS) and International Hip Outcome Tool, 12-component form (iHOT-12), were used to assess hip function[22–24]. VAS, mHHS, and iHOT-12 scores were routinely collected preoperatively via questionnaires. Gait analysis The participants were required to wear fitted swimming trunks and remain barefoot during testing. A total of 37 reflective markers were attached to the participants, which were placed on the lateral and medial malleoli, heel, midpoint of the second metatarsophalangeal joint, first metatarsophalangeal joint, fifth metatarsophalangeal joint, lower one-third and upper one-third of the tibia, lateral lower one-third of the leg, tibial tuberosity, medial and lateral femoral condyles, anterior thigh, lateral thigh, anterior superior iliac spine, posterior superior iliac spine, highest point of the iliac crest, acromion, and right scapula. All patients and healthy participants were marked by the same tester (H.Y.A.) to ensure that the testing results were not affected by intertester variability. Prior to testing, the participants were allowed to walk barefoot at their self-perceived comfortable speed along a walkway to acclimate to the testing environment and to collect static calibration data. At the start of the test, the participants began walking from a premeasured starting point, ensuring that one foot unintentionally stepped on the first force plate while the other foot stepped on the second force plate. A successful trial was characterized by each foot making contact with a force plate, and participants were instructed to walk at their self-perceived comfortable speed along the testing walkway, with three valid data collections performed. Kinematic parameters of the lower limbs during walking were captured via an 8-camera infrared high-speed motion capture system (Vicon, Nexus, T40, UK) at a sampling frequency of 100 Hz. Kinetic parameters of the lower limbs during walking were collected via two three-dimensional force plates (AMTI, BP400600, USA) at a sampling frequency of 1000 Hz. As shown in Fig. 1 , a complete gait cycle includes the entire action phase from heel strike to the subsequent heel strike of the same foot. Taking one side as the reference, the entire gait cycle is divided into five phases. Data reduction and analysis All kinematic and dynamic data were processed via Visual3D software (C-Motion, USA). The three-dimensional coordinates of all the markers were smoothed via a Butterworth low-pass filter with a cutoff frequency set at 10 Hz, while the dynamic data were left unsmoothed. The moment when the vertical ground reaction force exceeded 20 N was defined as the foot contact moment, whereas the moment when it fell below 20 N was designated the foot-off moment. Lower limb segment coordinate systems were established on the basis of the positions of the markers. The hip joint center was calculated according to the methodology outlined by Bell[25]. The center of rotation for the knee joint was defined as the midpoint between the medial and lateral femoral condyles, and the center of rotation for the ankle joint was established as the midpoint between the medial and lateral malleoli. Three-dimensional angles for the pelvis, hip, knee and ankle joints were calculated via the Euler angle method, and three-dimensional moments for the hip, knee and ankle joints were computed via inverse dynamics. The joint moment presented in this study is classified as an endogenous moment. The dynamic parameters included the normalized three-dimensional moment for the hip, knee and ankle joints during the entire gait cycle. The kinematic parameters included normalized three-dimensional angles for each joint throughout the entire gait cycle. The ground reaction forces were standardized as multiples of body weight (BW); the moments were standardized as multiples of 9.8×height×weight, expressed in units of 9.8×BW×BH. For each of the kinematic and kinetic components, 101 discrete points corresponding to the 0–100% stance phase at a 1% interval were normalized via a cubic spline for statistical analysis. Statistical analysis One-way ANOVA was conducted to analyze the differences in demographic variables, walking speed and joint range of motion. A post hoc analysis of covariance with Bonferroni correction (p < 0.0167) between every two groups was performed. Independent sample t tests and Wilcoxon signed-rank tests were used to compare the differences in radiological variables. Qualitative data were analyzed via either a chi-square test or Fisher’s exact test. The level of statistical significance was set at P < 0.05. The kinematic and kinetic parameters of the hip, knee, and ankle were compared among the control group (the random side of the healthy control group), FAIS group (involved side), and FAIS + BDDH group (involved side) via one-way analysis of variance (ANOVA). A post hoc analysis of covariance with Bonferroni correction (p < 0.0167) between every two groups was performed. All statistical analyses were performed in MATLAB software (version: 2016b, MathWorks, USA) using Statistical Parametric Mapping (SPM) (p < 0.05). Results As shown in Fig. 2 , a total of 28 volunteers aged 18–50 years who were diagnosed with cam-type FAIS and scheduled for hip arthroscopy were recruited. Of these, 14 participants were diagnosed with BDDH (LCEA: 18° < LCEA < 25°). All participants were recruited from the admission records of a sports medicine physician (Y.X.). Additionally, 14 asymptomatic control participants with no history of hip or groin pain or lower extremity surgery were recruited from the university community. The study was approved by the institutional medical research ethics committee, and written informed consent was obtained from all participants. As shown in Table 1 , no significant differences were observed in the baseline data regarding sex, age, BMI, AA, duration of symptoms, patient-reported outcomes, or imaging scores (p > 0.05). The lateral center-edge angle in the BDDH group was significantly smaller than that in the FAIS group (p < 0.001). Table 1 Demographics, Walking Speeds, and Outcome Measures for the Study Groups FAIS + BDDH(n = 14) FAIS(n = 14) Healthy Control(n = 14) F/X² P Value BMI(‾x ± s, kg/m²) 20.59 ± 1.5 21.35 ± 3.4 22.81 ± 2.89 2.417 0.102 Age(‾x ± s, y) 32.14 ± 8.58 32.5 ± 6.64 28.71 ± 5.97 1.196 0.313 Walking speed(x ± s, m/s) 1.12 ± 0.14 1.17 ± 0.16 1.24 ± 0.13 2.719 0.078 Sex(Male: Female) 3: 11 2: 12 6: 8 3.202 0.202 AA 62.49 ± 7.84 68.08 ± 12.25 / 2.112 0.158 LCEA 22.71 ± 2.23 34.26 ± 4.81 / 66.547 <0.001 Duration of symptoms, months(‾x ± s, m) 27.86 ± 33.85 26.57 ± 26.84 / 0.012 0.912 VAS 3.07 ± 1.77 3.86 ± 1.61 / 1.505 0.231 MHHS 72.64 ± 12.85 69.71 ± 12.57 / 0.372 0.547 IHOT-12 44.03 ± 14.71 46.16 ± 13.69 / 0.158 0.695 SHOMRI-Total score 7.86 ± 2.83 6.79 ± 2.94 / 0.967 0.335 SHOMRI-Labrum 11.71 ± 3.33 10.21 ± 3.66 / 1.283 0.268 Note: an indicates a comparison with BDDH + FAIS , p < 0.05; b indicates a comparison with FAIS , p < 0.05; all pairwise comparisons were adjusted via the Bonferroni correction. Hip Hip Joint in the Sagittal Plane: Angle: During the terminal stance phase (29%-35%), the hip flexion angle in FAI + BDDH patients was significantly greater than that in patients with isolated FAIS (p < 0.05). (Fig. 3 A). Moment: During the loading response phase (2%, 4%), the moment of hip extension in FAI + BDDH patients was significantly shorter than that in healthy controls (p < 0.05) (Fig. 3 B). Hip Joint in the Coronal Plane: Angle: No statistically significant differences were detected in the hip joint angle in the coronal plane among FAI + BDDH patients, isolated FAIS patients and healthy controls (p > 0.05) (Fig. 3 C). Moment: During the loading response, midstance and terminal stance phases (3%-14%, 16%, 40%-51%), the hip abduction moment in FAI + BDDH patients was significantly smaller than that in healthy controls (p < 0.05). Similarly, during the loading response phase (5%-6%), the hip abduction moment in isolated FAIS patients was significantly smaller than that in healthy controls (p < 0.05) (Fig. 3 D). Hip Joint in the Transverse Plane: Angle: During the loading response, midstance, terminal stance and terminal swing phases (4%-12%, 14%, 40%-51%, 92%-95%), the internal rotation angle of the hip in FAI + BDDH patients was significantly greater than that in healthy controls (p < 0.05). In isolated FAIS patients, the hip external rotation angle was significantly smaller than that in healthy controls (p < 0.05) during the loading response phase (5%-6%) (Fig. 3 E). Moment: During the loading response phase (5%-7%), the hip external rotation moment in FAI + BDDH patients was significantly smaller than that in healthy controls (p < 0.05). Similarly, during the loading response phase (5%-8%), the hip external rotation moment in isolated FAIS patients was significantly smaller than that in healthy controls (p < 0.05) (Fig. 3 F). Knee Knee Joint in the Sagittal Plane Angle: No statistically significant differences were detected in the knee joint angle in the sagittal plane among FAI + BDDH patients, isolated FAIS patients and healthy controls (p > 0.05) (Fig. 4 A). Moment: During the terminal stance phase (30%-48%), the knee extension moment in FAI + BDDH patients was significantly shorter than that in healthy controls (p < 0.05). Similarly, during the loading response, terminal stance and preswing phases (2%, 32%-46%, 58%, and 60%, respectively), the knee extension moment in isolated FAIS patients was significantly shorter than that in healthy controls (p < 0.05) (Fig. 4 B). Knee Joint in the Coronal Plane Angle: No statistically significant differences were detected in the knee joint angle in the coronal plane among FAI + BDDH patients, isolated FAIS patients and healthy controls (p > 0.05) (Fig. 4 C). Moment: During the loading response phase (6%), the knee adduction moment in FAI + BDDH patients was significantly smaller than that in healthy controls (p < 0.05). Similarly, during the loading response phase (6%-7%), the knee adduction moment in isolated FAIS patients was significantly smaller than that in healthy controls (p < 0.05) (Fig. 4 D). Knee Joint in the Transverse Plane Angle: During the loading response and initial swing phases (5%, 62%), the knee external rotation angle in FAI + BDDH patients was significantly smaller than that in healthy controls (p < 0.05). Additionally, during the initial swing phase (5%-6%), the external rotation angle in isolated patients was significantly smaller than that in healthy controls (p < 0.05) (Fig. 4 E). Moment: During the terminal stance phase (35%-50%), the knee internal rotation moment in FAI + BDDH patients was significantly smaller than that in healthy controls (p 0.05) (Fig. 4 F). Ankle Ankle Joint in the Sagittal Plane Angle: During midstance (11%-14%), the ankle plantar flexion angle in FAI + BDDH patients was significantly greater than that in healthy controls (p < 0.05). During preswing (52%, 55%-56%), significant differences in the ankle plantar flexion angle were observed between FAI + BDDH patients and healthy controls (p < 0.05) (Fig. 5 A). Moment: During terminal stance (37%-51%), the ankle dorsiflexion moment in FAI + BDDH patients was significantly smaller than that in healthy controls (p < 0.05). In isolated FAIS patients, during the terminal stance phase (32%-49%), the ankle dorsiflexion moment was significantly smaller than that in healthy controls (p < 0.05) (Fig. 5 B). Ankle Joint in the Coronal Plane Angle: During terminal stance (46%-48%), the ankle eversion angle in FAI + BDDH patients was significantly greater than that in healthy controls (p < 0.05) (Fig. 5 C). Moment: During the loading response phase (0%-1%), the ankle inversion moment in FAI + BDDH patients was significantly greater than that in healthy controls (p < 0.05) (Fig. 5 D). Ankle Joint in the Transverse Plane Angle: During the loading response phase (0%-1%), the internal rotation angle of the ankle in FAI + BDDH patients was significantly smaller than that in healthy controls (p < 0.05) (Fig. 5 E). Moment: During terminal stance (37%-51%), the internal rotation moment of the ankle in FAI + BDDH patients was significantly smaller than that in healthy controls (p < 0.05). In isolated FAIS patients, during the terminal stance phase (36%-52%), the internal rotation moment of the ankle was significantly smaller than that in healthy controls (p < 0.05) (Fig. 5 F). Pelvis Pelvis in the Sagittal Plane Angle: No statistically significant differences were detected in the pelvis joint angles in the sagittal plane among FAI + BDDH patients, isolated FAIS patients and healthy controls (p > 0.05) (Fig. 6 A). Pelvis in the Coronal Plane Angle: No statistically significant differences were detected in the pelvis joint angles in the coronal plane among FAI + BDDH patients, isolated FAIS patients and healthy controls (p > 0.05) (Fig. 6 B). Pelvis in the transverse plane Angle: During the loading response phase (0%-1%), the internal rotation angle of the pelvis in isolated FAI patients was significantly smaller than that in healthy controls (p 0.05) (Table 2 ). Table 2 Range of motion BDDH + FAIS(n = 14) FAIS(n = 14) Healthy Control(n = 14) F P Value HIP ROM sagittal 43.81 ± 3.27 46.11 ± 5.82 46.86 ± 3.79 1.799 0.179 HIP ROM coronal 13.82 ± 2.64 15.35 ± 2.11 15.83 ± 2.81 2.384 0.106 HIP ROM transverse 18.02 ± 3.61 20.99 ± 8.77 16.23 ± 4.99 2.118 0.134 PELVIS ROM sagittal -4.82 ± 1.34 -5.22 ± 1.94 -4.32 ± 0.87 1.362 0.268 PELVIS ROM coronal 10.97 ± 2.31 10.66 ± 2.37 12.07 ± 2.65 1.28 0.29 PELVIS ROM transverse 15.08 ± 3.92 16.45 ± 12.05 14.56 ± 4.34 0.224 0.8 Note: an indicates a comparison with BDDH + FAIS , p < 0.05; b indicates a comparison with FAIS , p < 0.05; all pairwise comparisons were adjusted via the Bonferroni correction. Discussion Our study revealed that patients with FAIS combined with BDDH presented more compensatory biomechanical characteristics during gait than did those with isolated FAIS, including biomechanical defects of the hip joint, similar to DDH, stiffer knee joints, and compensatory alterations in the ankle joints. To the best of our knowledge, this is the first study to evaluate in vivo kinematics and kinetics in patients with combined FAIS and BDDH during level walking. In the sagittal plane of the hip joint, we observed reduced hip extension angles during the preswing phase in BDDH patients compared with those in isolated FAIS patients. Previous studies have reported reduced hip extension angles in FAIS patients[26–29], which may result from the joint approaching the end range of motion during extension. Increased tension in the hip joint ligaments and iliopsoas tendons can cause high pressure at the anterior–superior junction of the femoral head and neck[30, 31]. To avoid this mechanically stressful and pain-inducing scenario, patients adopt a modified gait pattern. Our study suggests that this abnormal gait pattern may be more pronounced in BDDH patients. Additionally, we found that the hip extension moment was reduced during the loading response in patients with combined BDDH, whereas this reduction did not reach statistical significance in patients with isolated FAIS. This decrease may stem from weakened hip abductors, extensors, and flexors, as reported in DDH patients[32], although this has not been confirmed in BDDH patients. Future research should focus on muscle strength assessments in BDDH patients to clarify the biomechanical mechanisms involved. We also observed a significantly reduced hip abduction moment during the loading response and midstance phases in patients with combined BDDH compared with healthy controls. In isolated FAIS patients, this phenomenon was observed only during the loading response. This reduction may be attributed to hip abductor weakness, which has been shown in DDH patients to involve shorter abductor moment arms, weaker abductor muscles[32], and a reduced hip abduction moment[33]. Our findings suggest that similar phenomena may occur in BDDH patients, but further electromyographic studies are needed to validate this conclusion. Patients with combined BDDHs exhibited greater hip internal rotation during the terminal stance and preswing phases. Our findings suggest that reduced osseous coverage may allow BDDH patients to achieve a greater range of hip internal rotation during gait. We also found that the knees of FAIS + BDDH patients displayed a gait pattern similar to that observed in ACL injuries, characterized by a combination of "stiffening gait" (extension deficiency and reduced extension moment) and "pivot-shift gait" (extension deficiency, along with reduced extension and internal rotation moment). Although the knee flexion angles during the loading response did not significantly differ, a similar trend was observed. The “pivot-shift avoidance” gait likely serves to prevent the knee from entering positions that could lead to anterolateral rotatory knee instability during terminal stance. This gait pattern was initially identified in patients with acute ACL injuries[34]. Previous studies have reported ipsilateral knee pain (IKP) in FAIS patients[35]. Our study biomechanically supports this observation. Our study revealed that the ankle dorsiflexion angle during preswing was significantly greater in FAI + BDDH patients than in healthy controls. Moreover, the ankle joint moment significantly decreased. As the external moment must be counteracted by the internal moment, this finding may indicate ankle muscle weakness in FAI + BDDH patients. Ankle dorsiflexion moment reductions were also observed in isolated FAIS patients. However, we detected increased ankle eversion and a decreased external rotation moment in FAI + BDDH patients, further supporting our conclusion that ankle compensation may be present in these patients during gait. Owing to the cross-sectional nature of this study, we cannot confirm whether this compensation is caused by BDDH or whether it exacerbates symptoms or represents a compensatory mechanism. To our knowledge, no previous studies have examined the dynamic relationship between the ankle and hip joints during gait in BDDH patients. Instability in adjacent joints can profoundly impact hip joint function. Future research should investigate the dynamic interplay between the ankle and hip and evaluate whether ankle-strengthening exercises benefit FAIS patients. The range of motion results revealed no significant differences between the FAIS combined with BDDH, isolated FAIS, and healthy control groups. These findings suggest that acetabular coverage and Cam deformities may have a limited impact on the joint range of motion during gait. Previous studies have reported a reduction in the pelvic and hip joint sagittal and coronal plane angles[26, 36–38]; however, our study did not observe this phenomenon. This may be due to sample selection, as we did not include Pincer-type FAIS patients in our study. Future research should further investigate the impact of acetabular coverage on joint range of motion during gait. This study offers novel biomechanical insights into the gait abnormalities of patients with combined FAIS and BDDH, with significant implications for clinical practice. Our findings demonstrate that patients with FAIS and BDDH exhibit more severe biomechanical compensation than those with isolated FAIS, including biomechanical defects of the hip joint similar to DDH, increased knee stiffness, and compensatory alterations in the ankle joint. These findings highlight the need for a multifaceted clinical approach that addresses both the structural and functional impairments characteristic of this patient population. The identification of gait patterns resembling those observed in anterior cruciate ligament (ACL) injury patients, such as "stiffening gait" and "pivot-shift gait," suggests that FAIS + BDDH patients may be at increased risk for knee instability. This underscores the clinical importance of early diagnosis and intervention, with an emphasis on strengthening knee stabilizing muscles to prevent further joint instability. The reductions in hip extension and abduction moment observed in these patients, along with ankle compensation, indicate deficits in muscle strength and joint control, which may be addressed through targeted rehabilitation programs focusing on the hip abductors, knee extensors, and ankle stabilizers. Such interventions may significantly improve gait mechanics and overall functional outcomes. Furthermore, our study provides a deeper understanding of the dynamic interaction between the hip joint and adjacent joints, such as the knee and ankle, in patients with combined FAIS and BDDH. Given the observed biomechanical interdependencies, future research should focus on exploring the efficacy of joint-specific rehabilitation strategies and evaluating whether strengthening adjacent joints (e.g., the ankle) can mitigate the biomechanical deficits observed in the hip and knee. These insights could lead to the development of more refined, evidence-based therapeutic protocols tailored to this complex patient group. In conclusion, this study contributes to the growing body of literature on the biomechanical profile of FAIS + BDDH patients, offering valuable evidence that can inform the development of more personalized and effective treatment strategies. By improving the understanding of gait abnormalities and their underlying mechanisms, this research has the potential to enhance clinical outcomes, reduce the risk of joint instability, and improve the overall quality of life for individuals affected by these conditions. Limitations Our study has several limitations. First, we did not match participants for sex, age, or BMI, which may lower the level of evidence. Second, we investigated only biomechanical changes during level walking, an activity that minimally provokes the hip joint. Further research should incorporate more ecological walking protocols and include more strenuous activities, such as running or stair climbing, to provide a more comprehensive understanding. Finally, we did not perform pelvic anteroposterior radiographs for the healthy control group. Conclusion Patients with FAIS combined with BDDH exhibit a gait pattern characterized by biomechanical defects of the hip joint similar to those with DDH, increased knee stiffness, and compensatory alterations in the ankle joint compared with those with isolated FAIS. Declarations Ethics and Consent to Participate declarations Ethical approval from The Ethics Committee of Peking University Third Hospital approved this study (No. M2024138). Informed consent Informed consent was obtained from all individual participants included in the study. All methods were performed in accordance with the guidelines and regulations of the Ethics Committee of Peking University Third Hospital. Funding National Key Research and Development Program of China (2023YFE0119100) National Natural Science Foundation of China (82372496) Peking University Third Hospital (BYSYZD2023011) Peking University Third Hospital (BYSYZHKC2023111) The Capital Health Research and Development of Special (No. 2022-2Z-40915) Clinical trial number Not applicable. Authors' contributions 1. Conception and design of the study: Yuang Hao and Shuang Ren. 2. Acquisition of data: Yuang Hao, Yichuan Zhu, Shuang Ren, Tong-Chuan He 3. Analyses of data: Yuang Hao. 4. Drafting the work: Yuang Hao and Shuang Ren. 5. Revising it critically for important intellectual content: Xin Miao and Yan Xu. 6. Final approval of the version to be published: Yuang Hao, Shuang Ren, Yichuan Zhu, Tong-Chuan He, Xin Miao, and Yan Xu. Acknowledgements Not applicable. Consent for publication Not applicable. Data Availability declaration All relevant data supporting the conclusions are included within the article and tables. The datasets used and/or analyzed during the current study available from the corresponding author on reasonable request. Competing Interest declaration The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. References Ganz R, Parvizi J, Beck M, Leunig M, Nötzli H, Siebenrock K. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003(417):112 − 20. Beck M, Kalhor M, Leunig M, Ganz R. Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip. J Bone Joint Surg Br. 2005;87(7):1012-8. Sierra R, Trousdale R, Ganz R, Leunig M. Hip disease in the young, active patient: evaluation and nonarthroplasty surgical options. J Am Acad Orthop Surg. 2008;16(12):689–703. Clohisy J, St John L, Schutz A. Surgical treatment of femoroacetabular impingement: a systematic review of the literature. Clin Orthop Relat Res. 2010;468(2):555 − 64. Wang X, Song G, Zhang J. Arthroscopic Treatment of Labral Tears in Patients with Borderline Developmental Dysplasia of the Hip: A Retrospective Study with Mean 5.8 Years Follow-Up. Orthop Surg. 2021;13(6):1835-42. Della Rocca F, Di Francia V, Schiavi P, D'Ambrosi R. Hip arthroscopy and T-shaped capsular plication for the treatment of borderline dysplasia: a minimum 2-year follow-up. Eur J Orthop Surg Traumatol. 2022;32(3):449 − 58. McQuivey KS, Secretov E, Domb BG, Levy BA, Krych AJ, Neville M, et al. A Multicenter Study of Radiographic Measures Predicting Failure of Arthroscopy in Borderline Hip Dysplasia: Beware of the Tönnis Angle. Am J Sports Med. 2020;48(7):1608-15. Kraeutler MJ. Editorial Commentary: Most Patients With Borderline Hip Dysplasia Do Well After Hip Arthroscopy: Could Instability Be the Problem for Those Who Do Poorly? Arthroscopy. 2023;39(2):283-4. Zhang J, Li Z, Wu Y, Yu K, Gan L, Liu Y, et al. Borderline Developmental Dysplasia of the Hip With Osseous Impingement as Distinct From Femoroacetabular Impingement and Developmental Dysplasia of the Hip. Orthop J Sports Med. 2024;12(8):23259671241249948. Ding Z, Sun Y, Liu S, Chen J. Hip Arthroscopic Surgery in Borderline Developmental Dysplastic Hips: A Systematic Review. Am J Sports Med. 2019;47(10):2494 − 500. Song K, Gaffney BMM, Shelburne KB, Pascual-Garrido C, Clohisy JC, Harris MD. Dysplastic hip anatomy alters muscle moment arm lengths, lines of action, and contributions to joint reaction forces during gait. J Biomech. 2020;110:109968. Shepherd MC, Gaffney BMM, Song K, Clohisy JC, Nepple JJ, Harris MD. Femoral version deformities alter joint reaction forces in dysplastic hips during gait. J Biomech. 2022;135:111023. Wu T, Lohse KR, Van Dillen L, Song K, Clohisy JC, Harris MD. Are Abnormal Muscle Biomechanics and Patient-reported Outcomes Associated in Patients With Hip Dysplasia? Clin Orthop Relat Res. 2023;481(12):2380-9. Griffin DR, Dickenson EJ, O'Donnell J, Agricola R, Awan T, Beck M, et al. The Warwick Agreement on femoroacetabular impingement syndrome (FAI syndrome): an international consensus statement. Br J Sports Med. 2016;50(19):1169-76. Philippon M, Maxwell R, Johnston T, Schenker M, Briggs K. Clinical presentation of femoroacetabular impingement. Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 2007;15(8):1041-7. Mansor Y, Perets I, Close MR, Mu BH, Domb BG. In Search of the Spherical Femoroplasty: Cam Overresection Leads to Inferior Functional Scores Before and After Revision Hip Arthroscopic Surgery. Am J Sports Med. 2018;46(9):2061-71. Megerian MF, Strony JT, Mengers SR, Joseph NM, Salata MJ, Wetzel RJ. Use of Anatomic Radiographic Horizons for the Lateral Center-Edge Angle in the Classification of Hip Dysplasia. Am J Sports Med. 2022;50(13):3610-6. Hiza E, Dierckman BD, Guanche C, Applegate G, Shah D, Ryu JH. Reliability of the Tönnis Classification and Its Correlation With Magnetic Resonance Imaging and Intraoperative Chondral Damage. Arthroscopy. 2019;35(2):403-8. Lee S, Nardo L, Kumar D, Wyatt CR, Souza RB, Lynch J, et al. Scoring hip osteoarthritis with MRI (SHOMRI): A whole joint osteoarthritis evaluation system. J Magn Reson Imaging. 2015;41(6):1549-57. Liao TC, Samaan MA, Popovic T, Neumann J, Zhang AL, Link TM, et al. Abnormal Joint Loading During Gait in Persons With Hip Osteoarthritis Is Associated With Symptoms and Cartilage Lesions. J Orthop Sports Phys Ther. 2019;49(12):917 − 24. Lewińska A, Palczewski P, Piłat K, Cieszanowski A, Rongies W. The Use of Scoring Hip Osteoarthritis with MRI as an Assessment Tool for Physiotherapeutic Treatment in Patients with Osteoarthritis of the Hip. J Clin Med. 2021;11(1). Byrd JW. Hip arthroscopy: patient assessment and indications. Instr Course Lect. 2003;52:711-9. Griffin DR, Parsons N, Mohtadi NG, Safran MR. A short version of the International Hip Outcome Tool (iHOT-12) for use in routine clinical practice. Arthroscopy. 2012;28(5):611-6; quiz 6–8. Ebert JR, Raymond AC, Aujla RS, D'Alessandro P. The Effect of a Formal Nonoperative Management Program Combining a Hip Injection With Structured Adjunctive Exercise Rehabilitation in Patients With Symptomatic Femoroacetabular Impingement Syndrome. Am J Sports Med. 2023;51(3):694–706. Reize P, Müller O, Motzny S, Wülker N. [Prediction of the location of the center of rotation of the hip joint external landmarks]. Z Orthop Ihre Grenzgeb. 2006;144(5):492-6. Brisson N, Lamontagne M, Kennedy M, Beaulé P. The effects of cam femoroacetabular impingement corrective surgery on lower-extremity gait biomechanics. Gait Posture. 2013;37(2):258 − 63. Hunt M, Guenther J, Gilbart M. Kinematic and kinetic differences during walking in patients with and without symptomatic femoroacetabular impingement. Clinical biomechanics (Bristol, Avon). 2013;28(5):519 − 23. Lewis C, Khuu A, Loverro K. Gait Alterations in Femoroacetabular Impingement Syndrome Differ by Sex. J Orthop Sports Phys Ther. 2018;48(8):649 − 58. Ng K, Mantovani G, Modenese L, Beaulé P, Lamontagne M. Altered Walking and Muscle Patterns Reduce Hip Contact Forces in Individuals With Symptomatic Cam Femoroacetabular Impingement. Am J Sports Med. 2018;46(11):2615-23. Daenen B, Preidler K, Padmanabhan S, Brossmann J, Tyson R, Goodwin D, et al. Symptomatic herniation pits of the femoral neck: anatomic and clinical study. AJR Am J Roentgenol. 1997;168(1):149 − 53. Hewitt J, Guilak F, Glisson R, Vail T. Regional material properties of the human hip joint capsule ligaments. J Orthop Res. 2001;19(3):359 − 64. Harris MD, Shepherd MC, Song K, Gaffney BMM, Hillen TJ, Harris-Hayes M, et al. The biomechanical disadvantage of dysplastic hips. J Orthop Res. 2022;40(6):1387-96. Harris MD, MacWilliams BA, Bo Foreman K, Peters CL, Weiss JA, Anderson AE. Higher medially directed joint reaction forces are a characteristic of dysplastic hips: A comparative study using subject-specific musculoskeletal models. J Biomech. 2017;54:80 − 7. Hurd WJ, Snyder-Mackler L. Knee instability after acute ACL rupture affects movement patterns during the mid-stance phase of gait. J Orthop Res. 2007;25(10):1369-77. Zhu Y, Zhang S, Gao G, Wang H, Luan S, Wu K, et al. Concomitant Ipsilateral Knee Pain Is Associated With Worse Preoperative Functional Status and Short-Term Outcomes After Hip Arthroscopy in Patients With Femoroacetabular Impingement Syndrome. Arthroscopy. 2024;40(5):1490-9. Kennedy M, Lamontagne M, Beaulé P. Femoroacetabular impingement alters hip and pelvic biomechanics during gait Walking biomechanics of FAI. Gait Posture. 2009;30(1):41 − 4. Rylander J, Shu B, Favre J, Safran M, Andriacchi T. Functional testing provides unique insights into the pathomechanics of femoroacetabular impingement and an objective basis for evaluating treatment outcome. J Orthop Res. 2013;31(9):1461-8. Catelli D, Ng K, Kowalski E, Beaulé P, Lamontagne M. Modified gait patterns due to cam FAI syndrome remain unchanged after surgery. Gait Posture. 2019;72:135 − 41. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 16 May, 2025 Read the published version in BMC Musculoskeletal Disorders → Version 1 posted Editorial decision: Revision requested 24 Jan, 2025 Editor assigned by journal 24 Jan, 2025 Submission checks completed at journal 24 Jan, 2025 First submitted to journal 16 Jan, 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. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-5843084","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":406645576,"identity":"be0a4810-8bb6-44cc-bb15-11cd32fc239b","order_by":0,"name":"Yuang Hao","email":"","orcid":"","institution":"Beijing Sport University","correspondingAuthor":false,"prefix":"","firstName":"Yuang","middleName":"","lastName":"Hao","suffix":""},{"id":406645577,"identity":"57a90ca8-b3d4-40c0-ab20-a31bc0d51564","order_by":1,"name":"Shuang Ren","email":"","orcid":"","institution":"Peking University Third Hospital","correspondingAuthor":false,"prefix":"","firstName":"Shuang","middleName":"","lastName":"Ren","suffix":""},{"id":406645578,"identity":"3d0f5b8b-5dd2-4af1-a27c-9ed4bbde19db","order_by":2,"name":"Yichuan Zhu","email":"","orcid":"","institution":"Peking University Third Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yichuan","middleName":"","lastName":"Zhu","suffix":""},{"id":406645579,"identity":"2f5a3ccc-6e1e-4dcb-961c-661fde72d10d","order_by":3,"name":"Tong-Chuan He","email":"","orcid":"","institution":"University of Chicago","correspondingAuthor":false,"prefix":"","firstName":"Tong-Chuan","middleName":"","lastName":"He","suffix":""},{"id":406645580,"identity":"afba1898-7611-4fd5-955b-e0f4a33b7306","order_by":4,"name":"Xin Miao","email":"","orcid":"","institution":"Peking University Third Hospital","correspondingAuthor":false,"prefix":"","firstName":"Xin","middleName":"","lastName":"Miao","suffix":""},{"id":406645581,"identity":"a107f17a-d3cf-445c-9ca5-87d24c4e03e4","order_by":5,"name":"Yan Xu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAnklEQVRIiWNgGAWjYBACgwMgskLCjp9ELWcskiUbiNUCVsnYVsG44QCxWvjZzx6T5p0nwWxwgPnhoxvEaGHjyUs25t0mwSd5gM3YOIcoLQw5ho+BWpj5DvCwSROnhf+NwWHeORKMDcRrkQDZ0iDBOIEELW+MDecck0iWbCbaL/w5ZhJvaurs+NmbHz4mSgsCMJOmfBSMglEwCkYBPgAAbRMolN+CuYkAAAAASUVORK5CYII=","orcid":"","institution":"Peking University Third Hospital","correspondingAuthor":true,"prefix":"","firstName":"Yan","middleName":"","lastName":"Xu","suffix":""}],"badges":[],"createdAt":"2025-01-16 15:23:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5843084/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5843084/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s12891-025-08727-4","type":"published","date":"2025-05-16T15:58:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":74947037,"identity":"64ad0d90-5943-4b8b-b983-f5b3adbe2b92","added_by":"auto","created_at":"2025-01-28 15:43:07","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":114159,"visible":true,"origin":"","legend":"\u003cp\u003eGait cycle: Subphases in a gait cycle\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-5843084/v1/119e359d8580b0770a1e70b6.png"},{"id":74947038,"identity":"e573f3de-bd71-4622-beb1-4769d7a4e1f3","added_by":"auto","created_at":"2025-01-28 15:43:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":59401,"visible":true,"origin":"","legend":"\u003cp\u003eFlow chart of patient selection\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-5843084/v1/862aa83efe29bd3a37ac0311.png"},{"id":74947040,"identity":"26c03fe7-3ba9-4515-80e9-703adb27d4a2","added_by":"auto","created_at":"2025-01-28 15:43:07","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":197232,"visible":true,"origin":"","legend":"\u003cp\u003eFull-cycle hip joint angle and moment. SPM results are displayed below the figure and indicate significant (p \u0026lt; 0.05) differences between (a) FAI and Healthy Control, (b) FAI+BDDH and Healthy Control, and (c) FAI+BDDH and FAI. The statistical differences in joint moments occurring after 60% of the gait cycle should be disregarded.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-5843084/v1/fb88a5766c462604dfdd6964.png"},{"id":74947052,"identity":"9ab544ee-96c8-495c-b75f-3523ec2cb2c7","added_by":"auto","created_at":"2025-01-28 15:43:07","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":220392,"visible":true,"origin":"","legend":"\u003cp\u003eFull-cycle knee joint angle and moment. SPM results are displayed below the figure and indicate significant (p \u0026lt; 0.05) differences between (a) FAI and Healthy Control, (b) FAI+BDDH and Healthy Control, and (c) FAI+BDDH and FAI. The statistical differences in joint moments occurring after 60% of the gait cycle should be disregarded.\u003c/p\u003e","description":"","filename":"image4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-5843084/v1/dfc4706b510e4e0e4f2a3aca.jpeg"},{"id":74947039,"identity":"3aa55ad8-28c2-4a0e-8421-f63891957217","added_by":"auto","created_at":"2025-01-28 15:43:07","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":199494,"visible":true,"origin":"","legend":"\u003cp\u003eFull-cycle ankle joint angle and moment. SPM results are displayed below the figure and indicate significant (p \u0026lt; 0.05) differences between (a) FAI and Healthy Control, (b) FAI+BDDH and Healthy Control, and (c) FAI+BDDH and FAI. The statistical differences in joint moments occurring after 60% of the gait cycle should be disregarded.\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-5843084/v1/be81fc0a38393587d81f41da.png"},{"id":74947047,"identity":"060f3eb0-bef3-4efd-b069-5c237cc32083","added_by":"auto","created_at":"2025-01-28 15:43:07","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":104407,"visible":true,"origin":"","legend":"\u003cp\u003eFull-cycle pelvis joint angle. SPM results are displayed below the figure and indicate significant (p \u0026lt; 0.05) differences between (a) FAI and Healthy Control, (b) FAI+BDDH and Healthy Control, and (c) FAI+BDDH and FAI.\u003c/p\u003e","description":"","filename":"image6.png","url":"https://assets-eu.researchsquare.com/files/rs-5843084/v1/8cb550924a3267118cb49ad4.png"},{"id":83067870,"identity":"46af2e5d-a3aa-4b17-9949-d92c35bfe17e","added_by":"auto","created_at":"2025-05-19 16:07:18","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1746272,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5843084/v1/e8c1b7b3-4869-4a73-8782-76e694c216fb.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Three-dimensional lower limb kinematics and kinetics in femoroacetabular impingement syndrome (FAIS) patients with and without borderline developmental dysplasia of the hip (BDDH) during level walking","fulltext":[{"header":"Background","content":"\u003cp\u003eFemoroacetabular impingement syndrome (FAIS) is a morphological abnormality of the hip joint that is commonly observed in young and active adults[1\u0026ndash;3]. In a healthy hip joint, sufficient femoral head‒neck offset helps prevent impingement between the femoral neck and the pelvis. Surgical intervention is a commonly employed treatment for FAIS. Existing evidence demonstrates that, in the short term, surgical procedures can lead to significant improvements in joint function and a reduction in pain, thereby enhancing overall clinical outcomes[1, 4]. Borderline developmental dysplasia of the hip (BDDH) refers to a condition falling between a normal hip and adult developmental dysplasia of the hip (DDH)[5]. BDDH is typically defined as an acetabular lateral center-edge angle (LCEA) between 18 and 25 degrees[6, 7]. Furthermore, BDDH combined with hip joint instability is more likely to result in failure during arthroscopic treatment[8]. BDDH has gained considerable clinical attention in recent years[9]. A systematic review reported that the failure rate of arthroscopic surgery in FAIS patients with combined BDDH (FAI\u0026thinsp;+\u0026thinsp;BDDH) is 14.1% [10].\u003c/p\u003e \u003cp\u003eAbnormal hip morphology or movements beyond the physiological range can result in repetitive low-impact loading, particularly during combined movements in the sagittal, frontal, and transverse planes, such as hip flexion, adduction, and internal rotation[1, 3]. Previous studies have reported abnormal gait patterns in patients with DDH [11\u0026ndash;13], with insufficient acetabular coverage identified as a primary reason contributing to these abnormalities. However, the underlying reasons for poor clinical outcomes in patients with BDDH remain poorly understood. Therefore, the aim of this study was to investigate the biomechanical characteristics associated with FAI\u0026thinsp;+\u0026thinsp;BDDH more thoroughly, with the goal of providing more effective guidance for rehabilitation strategies and clinical interventions.\u003c/p\u003e \u003cp\u003eTherefore, the primary purpose of this study was to identify the biomechanical alterations in the lower limbs of FAIS\u0026thinsp;+\u0026thinsp;BDDH patients compared with those of isolated FAI patients and healthy controls through gait analysis, with the aim of elucidating the potential impact of BDDH on patients with FAIS.\u003c/p\u003e \u003cp\u003eWe hypothesized that gait abnormalities in FAIS\u0026thinsp;+\u0026thinsp;BDDH patients would be more pronounced than those in isolated FAIS patients.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eParticipants\u003c/h2\u003e \u003cp\u003e After institutional review board approval, patients who underwent hip arthroscopy from March 2024 to November 2024 at our institute were selected for gait analysis. The inclusion criteria included patients who were diagnosed with FAIS on the basis of their clinical symptoms and radiographic findings[14]. The exclusion criteria were as follows: (1) previous lower limb surgery[15]; (2) concomitant hip conditions, including hip osteoarthritis (OA) with a T\u0026ouml;nnis grade\u0026thinsp;\u0026gt;\u0026thinsp;1, avascular necrosis, Legg-Calv\u0026eacute;-Perthes disease, osteoid osteoma, synovial chondromatosis, pigmented villonodular synovitis, and DDH (LCEA\u0026thinsp;\u0026lt;\u0026thinsp;18\u0026deg;); (3) lower extremity injuries within the past month; (4) other forms of arthritis, diabetes, or heart disease that limit daily activities; and (5) pincer-type FAIS (LCEA\u0026thinsp;\u0026gt;\u0026thinsp;40\u0026deg;).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eData collection\u003c/h3\u003e\n\u003cp\u003ePatient demographic characteristics, including age at surgery, sex, affected side, height, weight, body mass index (BMI) and duration of symptoms, were recorded.\u003c/p\u003e \u003cp\u003eRadiographic examinations were performed preoperatively to obtain an alpha angle (AA) in the Dunn view, lateral center edge angle (LCEA) and T\u0026ouml;nnis grade in the anteroposterior (AP) view, as described in previous studies[16\u0026ndash;18].\u003c/p\u003e \u003cp\u003eAll enrolled patients underwent preoperative MRI with a 3.0 T scanner. Fat-saturated proton density (FSPD) sequences and T2-weighted sequences were performed in the axial, coronal, and oblique sagittal planes, respectively. A previously validated, semiquantitative, MRI-based scoring system (scoring hip osteoarthritis with MRI [SHOMRI]) was used to assess abnormalities in the articular cartilage and labrum of the hip joint separately[19]. The SHOMRI system has been previously used in assessments of hip joint abnormalities in patients with hip OA[20, 21].\u003c/p\u003e\n\u003ch3\u003eSelf-reported outcomes\u003c/h3\u003e\n\u003cp\u003ePatient-reported outcomes (PROs), including the visual analog pain scale (VAS), modified Harris hip score (mHHS) and International Hip Outcome Tool, 12-component form (iHOT-12), were used to assess hip function[22\u0026ndash;24]. VAS, mHHS, and iHOT-12 scores were routinely collected preoperatively via questionnaires.\u003c/p\u003e\n\u003ch3\u003eGait analysis\u003c/h3\u003e\n\u003cp\u003eThe participants were required to wear fitted swimming trunks and remain barefoot during testing. A total of 37 reflective markers were attached to the participants, which were placed on the lateral and medial malleoli, heel, midpoint of the second metatarsophalangeal joint, first metatarsophalangeal joint, fifth metatarsophalangeal joint, lower one-third and upper one-third of the tibia, lateral lower one-third of the leg, tibial tuberosity, medial and lateral femoral condyles, anterior thigh, lateral thigh, anterior superior iliac spine, posterior superior iliac spine, highest point of the iliac crest, acromion, and right scapula. All patients and healthy participants were marked by the same tester (H.Y.A.) to ensure that the testing results were not affected by intertester variability. Prior to testing, the participants were allowed to walk barefoot at their self-perceived comfortable speed along a walkway to acclimate to the testing environment and to collect static calibration data. At the start of the test, the participants began walking from a premeasured starting point, ensuring that one foot unintentionally stepped on the first force plate while the other foot stepped on the second force plate. A successful trial was characterized by each foot making contact with a force plate, and participants were instructed to walk at their self-perceived comfortable speed along the testing walkway, with three valid data collections performed. Kinematic parameters of the lower limbs during walking were captured via an 8-camera infrared high-speed motion capture system (Vicon, Nexus, T40, UK) at a sampling frequency of 100 Hz. Kinetic parameters of the lower limbs during walking were collected via two three-dimensional force plates (AMTI, BP400600, USA) at a sampling frequency of 1000 Hz.\u003c/p\u003e \u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, a complete gait cycle includes the entire action phase from heel strike to the subsequent heel strike of the same foot. Taking one side as the reference, the entire gait cycle is divided into five phases.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eData reduction and analysis\u003c/h3\u003e\n\u003cp\u003eAll kinematic and dynamic data were processed via Visual3D software (C-Motion, USA). The three-dimensional coordinates of all the markers were smoothed via a Butterworth low-pass filter with a cutoff frequency set at 10 Hz, while the dynamic data were left unsmoothed. The moment when the vertical ground reaction force exceeded 20 N was defined as the foot contact moment, whereas the moment when it fell below 20 N was designated the foot-off moment.\u003c/p\u003e \u003cp\u003eLower limb segment coordinate systems were established on the basis of the positions of the markers. The hip joint center was calculated according to the methodology outlined by Bell[25]. The center of rotation for the knee joint was defined as the midpoint between the medial and lateral femoral condyles, and the center of rotation for the ankle joint was established as the midpoint between the medial and lateral malleoli. Three-dimensional angles for the pelvis, hip, knee and ankle joints were calculated via the Euler angle method, and three-dimensional moments for the hip, knee and ankle joints were computed via inverse dynamics.\u003c/p\u003e \u003cp\u003eThe joint moment presented in this study is classified as an endogenous moment. The dynamic parameters included the normalized three-dimensional moment for the hip, knee and ankle joints during the entire gait cycle. The kinematic parameters included normalized three-dimensional angles for each joint throughout the entire gait cycle. The ground reaction forces were standardized as multiples of body weight (BW); the moments were standardized as multiples of 9.8\u0026times;height\u0026times;weight, expressed in units of 9.8\u0026times;BW\u0026times;BH.\u003c/p\u003e \u003cp\u003eFor each of the kinematic and kinetic components, 101 discrete points corresponding to the 0\u0026ndash;100% stance phase at a 1% interval were normalized via a cubic spline for statistical analysis.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eOne-way ANOVA was conducted to analyze the differences in demographic variables, walking speed and joint range of motion. A post hoc analysis of covariance with Bonferroni correction (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0167) between every two groups was performed. Independent sample t tests and Wilcoxon signed-rank tests were used to compare the differences in radiological variables. Qualitative data were analyzed via either a chi-square test or Fisher\u0026rsquo;s exact test. The level of statistical significance was set at P\u0026thinsp;\u0026lt;\u0026thinsp;0.05. The kinematic and kinetic parameters of the hip, knee, and ankle were compared among the control group (the random side of the healthy control group), FAIS group (involved side), and FAIS\u0026thinsp;+\u0026thinsp;BDDH group (involved side) via one-way analysis of variance (ANOVA). A post hoc analysis of covariance with Bonferroni correction (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0167) between every two groups was performed. All statistical analyses were performed in MATLAB software (version: 2016b, MathWorks, USA) using Statistical Parametric Mapping (SPM) (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eAs shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, a total of 28 volunteers aged 18\u0026ndash;50 years who were diagnosed with cam-type FAIS and scheduled for hip arthroscopy were recruited. Of these, 14 participants were diagnosed with BDDH (LCEA: 18\u0026deg; \u0026lt; LCEA\u0026thinsp;\u0026lt;\u0026thinsp;25\u0026deg;). All participants were recruited from the admission records of a sports medicine physician (Y.X.). Additionally, 14 asymptomatic control participants with no history of hip or groin pain or lower extremity surgery were recruited from the university community. The study was approved by the institutional medical research ethics committee, and written informed consent was obtained from all participants.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, no significant differences were observed in the baseline data regarding sex, age, BMI, AA, duration of symptoms, patient-reported outcomes, or imaging scores (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The lateral center-edge angle in the BDDH group was significantly smaller than that in the FAIS group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\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, Walking Speeds, and Outcome Measures for the Study Groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFAIS\u0026thinsp;+\u0026thinsp;BDDH(n\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eFAIS(n\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eHealthy Control(n\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eF/X\u0026sup2;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eP Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eBMI(\u0026oline;x\u0026thinsp;\u0026plusmn;\u0026thinsp;s, kg/m\u0026sup2;)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e20.59\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e21.35\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e22.81\u0026thinsp;\u0026plusmn;\u0026thinsp;2.89\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.417\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.102\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"1\" nameend=\"c7\" namest=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAge(\u0026oline;x\u0026thinsp;\u0026plusmn;\u0026thinsp;s, y)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32.14\u0026thinsp;\u0026plusmn;\u0026thinsp;8.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e28.71\u0026thinsp;\u0026plusmn;\u0026thinsp;5.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.196\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.313\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eWalking speed(x\u0026thinsp;\u0026plusmn;\u0026thinsp;s, m/s)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.12\u0026thinsp;\u0026plusmn;\u0026thinsp;0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1.17\u0026thinsp;\u0026plusmn;\u0026thinsp;0.16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.24\u0026thinsp;\u0026plusmn;\u0026thinsp;0.13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.719\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.078\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSex(Male: Female)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3: 11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2: 12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6: 8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3.202\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.202\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eAA\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e62.49\u0026thinsp;\u0026plusmn;\u0026thinsp;7.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e68.08\u0026thinsp;\u0026plusmn;\u0026thinsp;12.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e2.112\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.158\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eLCEA\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.71\u0026thinsp;\u0026plusmn;\u0026thinsp;2.23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e34.26\u0026thinsp;\u0026plusmn;\u0026thinsp;4.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e66.547\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDuration of symptoms, months(\u0026oline;x\u0026thinsp;\u0026plusmn;\u0026thinsp;s, m)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27.86\u0026thinsp;\u0026plusmn;\u0026thinsp;33.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26.57\u0026thinsp;\u0026plusmn;\u0026thinsp;26.84\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.012\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.912\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eVAS\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.07\u0026thinsp;\u0026plusmn;\u0026thinsp;1.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.86\u0026thinsp;\u0026plusmn;\u0026thinsp;1.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.505\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.231\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMHHS\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e72.64\u0026thinsp;\u0026plusmn;\u0026thinsp;12.85\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e69.71\u0026thinsp;\u0026plusmn;\u0026thinsp;12.57\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.372\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.547\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eIHOT-12\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44.03\u0026thinsp;\u0026plusmn;\u0026thinsp;14.71\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e46.16\u0026thinsp;\u0026plusmn;\u0026thinsp;13.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.158\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.695\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSHOMRI-Total score\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.86\u0026thinsp;\u0026plusmn;\u0026thinsp;2.83\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.79\u0026thinsp;\u0026plusmn;\u0026thinsp;2.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.967\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.335\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e \u003cp\u003e\u003cb\u003eSHOMRI-Labrum\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.71\u0026thinsp;\u0026plusmn;\u0026thinsp;3.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10.21\u0026thinsp;\u0026plusmn;\u0026thinsp;3.66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e/\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.283\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.268\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003eNote: an indicates a comparison with \u003cb\u003eBDDH\u0026thinsp;+\u0026thinsp;FAIS\u003c/b\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05; b indicates a comparison with \u003cb\u003eFAIS\u003c/b\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05; all pairwise comparisons were adjusted via the Bonferroni correction.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003eHip\u003c/h3\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eHip Joint in the Sagittal Plane:\u003c/h2\u003e \u003cp\u003eAngle: During the terminal stance phase (29%-35%), the hip flexion angle in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly greater than that in patients with isolated FAIS (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eA).\u003c/p\u003e \u003cp\u003eMoment: During the loading response phase (2%, 4%), the moment of hip extension in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly shorter than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eB).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eHip Joint in the Coronal Plane:\u003c/h2\u003e \u003cp\u003eAngle: No statistically significant differences were detected in the hip joint angle in the coronal plane among FAI\u0026thinsp;+\u0026thinsp;BDDH patients, isolated FAIS patients and healthy controls (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003eMoment: During the loading response, midstance and terminal stance phases (3%-14%, 16%, 40%-51%), the hip abduction moment in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Similarly, during the loading response phase (5%-6%), the hip abduction moment in isolated FAIS patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eD).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eHip Joint in the Transverse Plane:\u003c/h2\u003e \u003cp\u003eAngle: During the loading response, midstance, terminal stance and terminal swing phases (4%-12%, 14%, 40%-51%, 92%-95%), the internal rotation angle of the hip in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly greater than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In isolated FAIS patients, the hip external rotation angle was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) during the loading response phase (5%-6%) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eE).\u003c/p\u003e \u003cp\u003eMoment: During the loading response phase (5%-7%), the hip external rotation moment in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Similarly, during the loading response phase (5%-8%), the hip external rotation moment in isolated FAIS patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eF).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eKnee\u003c/h2\u003e \u003cdiv id=\"Sec15\" class=\"Section3\"\u003e \u003ch2\u003eKnee Joint in the Sagittal Plane\u003c/h2\u003e \u003cp\u003eAngle: No statistically significant differences were detected in the knee joint angle in the sagittal plane among FAI\u0026thinsp;+\u0026thinsp;BDDH patients, isolated FAIS patients and healthy controls (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA).\u003c/p\u003e \u003cp\u003eMoment: During the terminal stance phase (30%-48%), the knee extension moment in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly shorter than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Similarly, during the loading response, terminal stance and preswing phases (2%, 32%-46%, 58%, and 60%, respectively), the knee extension moment in isolated FAIS patients was significantly shorter than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003eKnee Joint in the Coronal Plane\u003c/h2\u003e \u003cp\u003eAngle: No statistically significant differences were detected in the knee joint angle in the coronal plane among FAI\u0026thinsp;+\u0026thinsp;BDDH patients, isolated FAIS patients and healthy controls (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003eMoment: During the loading response phase (6%), the knee adduction moment in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Similarly, during the loading response phase (6%-7%), the knee adduction moment in isolated FAIS patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eD).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003eKnee Joint in the Transverse Plane\u003c/h2\u003e \u003cp\u003eAngle: During the loading response and initial swing phases (5%, 62%), the knee external rotation angle in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Additionally, during the initial swing phase (5%-6%), the external rotation angle in isolated patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eE).\u003c/p\u003e \u003cp\u003eMoment: During the terminal stance phase (35%-50%), the knee internal rotation moment in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Additionally, during the terminal stance phase (38%-46%), the internal rotation moment in isolated patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eF).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003eAnkle\u003c/h2\u003e \u003cdiv id=\"Sec19\" class=\"Section3\"\u003e \u003ch2\u003eAnkle Joint in the Sagittal Plane\u003c/h2\u003e \u003cp\u003eAngle: During midstance (11%-14%), the ankle plantar flexion angle in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly greater than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). During preswing (52%, 55%-56%), significant differences in the ankle plantar flexion angle were observed between FAI\u0026thinsp;+\u0026thinsp;BDDH patients and healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eA).\u003c/p\u003e \u003cp\u003eMoment: During terminal stance (37%-51%), the ankle dorsiflexion moment in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In isolated FAIS patients, during the terminal stance phase (32%-49%), the ankle dorsiflexion moment was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eB).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec20\" class=\"Section2\"\u003e \u003ch2\u003eAnkle Joint in the Coronal Plane\u003c/h2\u003e \u003cp\u003eAngle: During terminal stance (46%-48%), the ankle eversion angle in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly greater than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003eMoment: During the loading response phase (0%-1%), the ankle inversion moment in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly greater than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eD).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec21\" class=\"Section2\"\u003e \u003ch2\u003eAnkle Joint in the Transverse Plane\u003c/h2\u003e \u003cp\u003eAngle: During the loading response phase (0%-1%), the internal rotation angle of the ankle in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eE).\u003c/p\u003e \u003cp\u003eMoment: During terminal stance (37%-51%), the internal rotation moment of the ankle in FAI\u0026thinsp;+\u0026thinsp;BDDH patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In isolated FAIS patients, during the terminal stance phase (36%-52%), the internal rotation moment of the ankle was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eF).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec22\" class=\"Section2\"\u003e \u003ch2\u003ePelvis\u003c/h2\u003e \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e \u003ch2\u003ePelvis in the Sagittal Plane\u003c/h2\u003e \u003cp\u003eAngle: No statistically significant differences were detected in the pelvis joint angles in the sagittal plane among FAI\u0026thinsp;+\u0026thinsp;BDDH patients, isolated FAIS patients and healthy controls (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eA).\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec24\" class=\"Section2\"\u003e \u003ch2\u003ePelvis in the Coronal Plane\u003c/h2\u003e \u003cp\u003eAngle: No statistically significant differences were detected in the pelvis joint angles in the coronal plane among FAI\u0026thinsp;+\u0026thinsp;BDDH patients, isolated FAIS patients and healthy controls (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eB).\u003c/p\u003e \u003cdiv id=\"Sec25\" class=\"Section3\"\u003e \u003ch2\u003ePelvis in the transverse plane\u003c/h2\u003e \u003cp\u003eAngle: During the loading response phase (0%-1%), the internal rotation angle of the pelvis in isolated FAI patients was significantly smaller than that in healthy controls (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eNo significant differences were detected in the range of motion of the pelvis or hip joints across the three planes among the three groups (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eRange of motion\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBDDH\u0026thinsp;+\u0026thinsp;FAIS(n\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eFAIS(n\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eHealthy Control(n\u0026thinsp;=\u0026thinsp;14)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eP Value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHIP ROM sagittal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e43.81\u0026thinsp;\u0026plusmn;\u0026thinsp;3.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46.11\u0026thinsp;\u0026plusmn;\u0026thinsp;5.82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e46.86\u0026thinsp;\u0026plusmn;\u0026thinsp;3.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.799\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.179\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHIP ROM coronal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13.82\u0026thinsp;\u0026plusmn;\u0026thinsp;2.64\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.35\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e15.83\u0026thinsp;\u0026plusmn;\u0026thinsp;2.81\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.384\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.106\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eHIP ROM transverse\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18.02\u0026thinsp;\u0026plusmn;\u0026thinsp;3.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20.99\u0026thinsp;\u0026plusmn;\u0026thinsp;8.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e16.23\u0026thinsp;\u0026plusmn;\u0026thinsp;4.99\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.118\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.134\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePELVIS ROM sagittal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-4.82\u0026thinsp;\u0026plusmn;\u0026thinsp;1.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e-5.22\u0026thinsp;\u0026plusmn;\u0026thinsp;1.94\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e-4.32\u0026thinsp;\u0026plusmn;\u0026thinsp;0.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.362\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.268\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePELVIS ROM coronal\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.97\u0026thinsp;\u0026plusmn;\u0026thinsp;2.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.66\u0026thinsp;\u0026plusmn;\u0026thinsp;2.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12.07\u0026thinsp;\u0026plusmn;\u0026thinsp;2.65\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePELVIS ROM transverse\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.08\u0026thinsp;\u0026plusmn;\u0026thinsp;3.92\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.45\u0026thinsp;\u0026plusmn;\u0026thinsp;12.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14.56\u0026thinsp;\u0026plusmn;\u0026thinsp;4.34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.224\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eNote: an indicates a comparison with \u003cb\u003eBDDH\u0026thinsp;+\u0026thinsp;FAIS\u003c/b\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05; b indicates a comparison with \u003cb\u003eFAIS\u003c/b\u003e, p\u0026thinsp;\u0026lt;\u0026thinsp;0.05; all pairwise comparisons were adjusted via the Bonferroni correction.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur study revealed that patients with FAIS combined with BDDH presented more compensatory biomechanical characteristics during gait than did those with isolated FAIS, including biomechanical defects of the hip joint, similar to DDH, stiffer knee joints, and compensatory alterations in the ankle joints. To the best of our knowledge, this is the first study to evaluate in vivo kinematics and kinetics in patients with combined FAIS and BDDH during level walking. In the sagittal plane of the hip joint, we observed reduced hip extension angles during the preswing phase in BDDH patients compared with those in isolated FAIS patients. Previous studies have reported reduced hip extension angles in FAIS patients[26\u0026ndash;29], which may result from the joint approaching the end range of motion during extension. Increased tension in the hip joint ligaments and iliopsoas tendons can cause high pressure at the anterior\u0026ndash;superior junction of the femoral head and neck[30, 31]. To avoid this mechanically stressful and pain-inducing scenario, patients adopt a modified gait pattern. Our study suggests that this abnormal gait pattern may be more pronounced in BDDH patients. Additionally, we found that the hip extension moment was reduced during the loading response in patients with combined BDDH, whereas this reduction did not reach statistical significance in patients with isolated FAIS. This decrease may stem from weakened hip abductors, extensors, and flexors, as reported in DDH patients[32], although this has not been confirmed in BDDH patients. Future research should focus on muscle strength assessments in BDDH patients to clarify the biomechanical mechanisms involved. We also observed a significantly reduced hip abduction moment during the loading response and midstance phases in patients with combined BDDH compared with healthy controls. In isolated FAIS patients, this phenomenon was observed only during the loading response. This reduction may be attributed to hip abductor weakness, which has been shown in DDH patients to involve shorter abductor moment arms, weaker abductor muscles[32], and a reduced hip abduction moment[33]. Our findings suggest that similar phenomena may occur in BDDH patients, but further electromyographic studies are needed to validate this conclusion. Patients with combined BDDHs exhibited greater hip internal rotation during the terminal stance and preswing phases. Our findings suggest that reduced osseous coverage may allow BDDH patients to achieve a greater range of hip internal rotation during gait.\u003c/p\u003e \u003cp\u003eWe also found that the knees of FAIS\u0026thinsp;+\u0026thinsp;BDDH patients displayed a gait pattern similar to that observed in ACL injuries, characterized by a combination of \"stiffening gait\" (extension deficiency and reduced extension moment) and \"pivot-shift gait\" (extension deficiency, along with reduced extension and internal rotation moment).\u003c/p\u003e \u003cp\u003eAlthough the knee flexion angles during the loading response did not significantly differ, a similar trend was observed. The \u0026ldquo;pivot-shift avoidance\u0026rdquo; gait likely serves to prevent the knee from entering positions that could lead to anterolateral rotatory knee instability during terminal stance. This gait pattern was initially identified in patients with acute ACL injuries[34]. Previous studies have reported ipsilateral knee pain (IKP) in FAIS patients[35]. Our study biomechanically supports this observation.\u003c/p\u003e \u003cp\u003eOur study revealed that the ankle dorsiflexion angle during preswing was significantly greater in FAI\u0026thinsp;+\u0026thinsp;BDDH patients than in healthy controls. Moreover, the ankle joint moment significantly decreased. As the external moment must be counteracted by the internal moment, this finding may indicate ankle muscle weakness in FAI\u0026thinsp;+\u0026thinsp;BDDH patients. Ankle dorsiflexion moment reductions were also observed in isolated FAIS patients. However, we detected increased ankle eversion and a decreased external rotation moment in FAI\u0026thinsp;+\u0026thinsp;BDDH patients, further supporting our conclusion that ankle compensation may be present in these patients during gait. Owing to the cross-sectional nature of this study, we cannot confirm whether this compensation is caused by BDDH or whether it exacerbates symptoms or represents a compensatory mechanism. To our knowledge, no previous studies have examined the dynamic relationship between the ankle and hip joints during gait in BDDH patients. Instability in adjacent joints can profoundly impact hip joint function. Future research should investigate the dynamic interplay between the ankle and hip and evaluate whether ankle-strengthening exercises benefit FAIS patients.\u003c/p\u003e \u003cp\u003eThe range of motion results revealed no significant differences between the FAIS combined with BDDH, isolated FAIS, and healthy control groups. These findings suggest that acetabular coverage and Cam deformities may have a limited impact on the joint range of motion during gait. Previous studies have reported a reduction in the pelvic and hip joint sagittal and coronal plane angles[26, 36\u0026ndash;38]; however, our study did not observe this phenomenon. This may be due to sample selection, as we did not include Pincer-type FAIS patients in our study. Future research should further investigate the impact of acetabular coverage on joint range of motion during gait.\u003c/p\u003e \u003cp\u003eThis study offers novel biomechanical insights into the gait abnormalities of patients with combined FAIS and BDDH, with significant implications for clinical practice. Our findings demonstrate that patients with FAIS and BDDH exhibit more severe biomechanical compensation than those with isolated FAIS, including biomechanical defects of the hip joint similar to DDH, increased knee stiffness, and compensatory alterations in the ankle joint. These findings highlight the need for a multifaceted clinical approach that addresses both the structural and functional impairments characteristic of this patient population.\u003c/p\u003e \u003cp\u003eThe identification of gait patterns resembling those observed in anterior cruciate ligament (ACL) injury patients, such as \"stiffening gait\" and \"pivot-shift gait,\" suggests that FAIS\u0026thinsp;+\u0026thinsp;BDDH patients may be at increased risk for knee instability. This underscores the clinical importance of early diagnosis and intervention, with an emphasis on strengthening knee stabilizing muscles to prevent further joint instability. The reductions in hip extension and abduction moment observed in these patients, along with ankle compensation, indicate deficits in muscle strength and joint control, which may be addressed through targeted rehabilitation programs focusing on the hip abductors, knee extensors, and ankle stabilizers. Such interventions may significantly improve gait mechanics and overall functional outcomes.\u003c/p\u003e \u003cp\u003eFurthermore, our study provides a deeper understanding of the dynamic interaction between the hip joint and adjacent joints, such as the knee and ankle, in patients with combined FAIS and BDDH. Given the observed biomechanical interdependencies, future research should focus on exploring the efficacy of joint-specific rehabilitation strategies and evaluating whether strengthening adjacent joints (e.g., the ankle) can mitigate the biomechanical deficits observed in the hip and knee. These insights could lead to the development of more refined, evidence-based therapeutic protocols tailored to this complex patient group.\u003c/p\u003e \u003cp\u003eIn conclusion, this study contributes to the growing body of literature on the biomechanical profile of FAIS\u0026thinsp;+\u0026thinsp;BDDH patients, offering valuable evidence that can inform the development of more personalized and effective treatment strategies. By improving the understanding of gait abnormalities and their underlying mechanisms, this research has the potential to enhance clinical outcomes, reduce the risk of joint instability, and improve the overall quality of life for individuals affected by these conditions.\u003c/p\u003e \u003cdiv id=\"Sec27\" class=\"Section2\"\u003e \u003ch2\u003eLimitations\u003c/h2\u003e \u003cp\u003eOur study has several limitations. First, we did not match participants for sex, age, or BMI, which may lower the level of evidence. Second, we investigated only biomechanical changes during level walking, an activity that minimally provokes the hip joint. Further research should incorporate more ecological walking protocols and include more strenuous activities, such as running or stair climbing, to provide a more comprehensive understanding. Finally, we did not perform pelvic anteroposterior radiographs for the healthy control group.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003ePatients with FAIS combined with BDDH exhibit a gait pattern characterized by biomechanical defects of the hip joint similar to those with DDH, increased knee stiffness, and compensatory alterations in the ankle joint compared with those with isolated FAIS.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics and Consent to Participate declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthical approval from The Ethics Committee of Peking University Third Hospital approved this study (No. M2024138). Informed consent Informed consent was obtained from all individual participants included in the study. All methods were performed in accordance with the guidelines and regulations of the Ethics Committee of Peking University Third Hospital.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNational Key Research and Development Program of China (2023YFE0119100)\u003c/p\u003e\n\u003cp\u003eNational Natural Science Foundation of China (82372496)\u003c/p\u003e\n\u003cp\u003ePeking University Third Hospital (BYSYZD2023011)\u003c/p\u003e\n\u003cp\u003ePeking University Third Hospital (BYSYZHKC2023111)\u003c/p\u003e\n\u003cp\u003eThe Capital Health Research and Development of Special (No. 2022-2Z-40915)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e1. Conception and design of the study: Yuang Hao and Shuang Ren.\u003c/p\u003e\n\u003cp\u003e2. Acquisition of data: Yuang Hao, Yichuan Zhu, Shuang Ren, Tong-Chuan He\u003c/p\u003e\n\u003cp\u003e3. Analyses of data: Yuang Hao.\u003c/p\u003e\n\u003cp\u003e4. Drafting the work: Yuang Hao and Shuang Ren.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e5. Revising it critically for important intellectual content: Xin Miao and Yan Xu.\u003c/p\u003e\n\u003cp\u003e6. Final approval of the version to be published: Yuang Hao, Shuang Ren, Yichuan Zhu, Tong-Chuan He, Xin Miao, and Yan Xu.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll relevant data supporting the conclusions are included within the article and tables. The datasets used and/or analyzed during the current study available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interest declaration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eGanz R, Parvizi J, Beck M, Leunig M, N\u0026ouml;tzli H, Siebenrock K. Femoroacetabular impingement: a cause for osteoarthritis of the hip. Clin Orthop Relat Res. 2003(417):112\u0026thinsp;\u0026minus;\u0026thinsp;20.\u003c/li\u003e\n \u003cli\u003eBeck M, Kalhor M, Leunig M, Ganz R. Hip morphology influences the pattern of damage to the acetabular cartilage: femoroacetabular impingement as a cause of early osteoarthritis of the hip. J Bone Joint Surg Br. 2005;87(7):1012-8.\u003c/li\u003e\n \u003cli\u003eSierra R, Trousdale R, Ganz R, Leunig M. Hip disease in the young, active patient: evaluation and nonarthroplasty surgical options. J Am Acad Orthop Surg. 2008;16(12):689\u0026ndash;703.\u003c/li\u003e\n \u003cli\u003eClohisy J, St John L, Schutz A. Surgical treatment of femoroacetabular impingement: a systematic review of the literature. Clin Orthop Relat Res. 2010;468(2):555\u0026thinsp;\u0026minus;\u0026thinsp;64.\u003c/li\u003e\n \u003cli\u003eWang X, Song G, Zhang J. Arthroscopic Treatment of Labral Tears in Patients with Borderline Developmental Dysplasia of the Hip: A Retrospective Study with Mean 5.8 Years Follow-Up. Orthop Surg. 2021;13(6):1835-42.\u003c/li\u003e\n \u003cli\u003eDella Rocca F, Di Francia V, Schiavi P, D\u0026apos;Ambrosi R. Hip arthroscopy and T-shaped capsular plication for the treatment of borderline dysplasia: a minimum 2-year follow-up. Eur J Orthop Surg Traumatol. 2022;32(3):449\u0026thinsp;\u0026minus;\u0026thinsp;58.\u003c/li\u003e\n \u003cli\u003eMcQuivey KS, Secretov E, Domb BG, Levy BA, Krych AJ, Neville M, et al. A Multicenter Study of Radiographic Measures Predicting Failure of Arthroscopy in Borderline Hip Dysplasia: Beware of the T\u0026ouml;nnis Angle. Am J Sports Med. 2020;48(7):1608-15.\u003c/li\u003e\n \u003cli\u003eKraeutler MJ. Editorial Commentary: Most Patients With Borderline Hip Dysplasia Do Well After Hip Arthroscopy: Could Instability Be the Problem for Those Who Do Poorly? Arthroscopy. 2023;39(2):283-4.\u003c/li\u003e\n \u003cli\u003eZhang J, Li Z, Wu Y, Yu K, Gan L, Liu Y, et al. Borderline Developmental Dysplasia of the Hip With Osseous Impingement as Distinct From Femoroacetabular Impingement and Developmental Dysplasia of the Hip. Orthop J Sports Med. 2024;12(8):23259671241249948.\u003c/li\u003e\n \u003cli\u003eDing Z, Sun Y, Liu S, Chen J. Hip Arthroscopic Surgery in Borderline Developmental Dysplastic Hips: A Systematic Review. Am J Sports Med. 2019;47(10):2494\u0026thinsp;\u0026minus;\u0026thinsp;500.\u003c/li\u003e\n \u003cli\u003eSong K, Gaffney BMM, Shelburne KB, Pascual-Garrido C, Clohisy JC, Harris MD. Dysplastic hip anatomy alters muscle moment arm lengths, lines of action, and contributions to joint reaction forces during gait. J Biomech. 2020;110:109968.\u003c/li\u003e\n \u003cli\u003eShepherd MC, Gaffney BMM, Song K, Clohisy JC, Nepple JJ, Harris MD. Femoral version deformities alter joint reaction forces in dysplastic hips during gait. J Biomech. 2022;135:111023.\u003c/li\u003e\n \u003cli\u003eWu T, Lohse KR, Van Dillen L, Song K, Clohisy JC, Harris MD. Are Abnormal Muscle Biomechanics and Patient-reported Outcomes Associated in Patients With Hip Dysplasia? Clin Orthop Relat Res. 2023;481(12):2380-9.\u003c/li\u003e\n \u003cli\u003eGriffin DR, Dickenson EJ, O\u0026apos;Donnell J, Agricola R, Awan T, Beck M, et al. The Warwick Agreement on femoroacetabular impingement syndrome (FAI syndrome): an international consensus statement. Br J Sports Med. 2016;50(19):1169-76.\u003c/li\u003e\n \u003cli\u003ePhilippon M, Maxwell R, Johnston T, Schenker M, Briggs K. Clinical presentation of femoroacetabular impingement. Knee surgery, sports traumatology, arthroscopy : official journal of the ESSKA. 2007;15(8):1041-7.\u003c/li\u003e\n \u003cli\u003eMansor Y, Perets I, Close MR, Mu BH, Domb BG. In Search of the Spherical Femoroplasty: Cam Overresection Leads to Inferior Functional Scores Before and After Revision Hip Arthroscopic Surgery. Am J Sports Med. 2018;46(9):2061-71.\u003c/li\u003e\n \u003cli\u003eMegerian MF, Strony JT, Mengers SR, Joseph NM, Salata MJ, Wetzel RJ. Use of Anatomic Radiographic Horizons for the Lateral Center-Edge Angle in the Classification of Hip Dysplasia. Am J Sports Med. 2022;50(13):3610-6.\u003c/li\u003e\n \u003cli\u003eHiza E, Dierckman BD, Guanche C, Applegate G, Shah D, Ryu JH. Reliability of the T\u0026ouml;nnis Classification and Its Correlation With Magnetic Resonance Imaging and Intraoperative Chondral Damage. Arthroscopy. 2019;35(2):403-8.\u003c/li\u003e\n \u003cli\u003eLee S, Nardo L, Kumar D, Wyatt CR, Souza RB, Lynch J, et al. Scoring hip osteoarthritis with MRI (SHOMRI): A whole joint osteoarthritis evaluation system. J Magn Reson Imaging. 2015;41(6):1549-57.\u003c/li\u003e\n \u003cli\u003eLiao TC, Samaan MA, Popovic T, Neumann J, Zhang AL, Link TM, et al. Abnormal Joint Loading During Gait in Persons With Hip Osteoarthritis Is Associated With Symptoms and Cartilage Lesions. J Orthop Sports Phys Ther. 2019;49(12):917\u0026thinsp;\u0026minus;\u0026thinsp;24.\u003c/li\u003e\n \u003cli\u003eLewińska A, Palczewski P, Piłat K, Cieszanowski A, Rongies W. The Use of Scoring Hip Osteoarthritis with MRI as an Assessment Tool for Physiotherapeutic Treatment in Patients with Osteoarthritis of the Hip. J Clin Med. 2021;11(1).\u003c/li\u003e\n \u003cli\u003eByrd JW. Hip arthroscopy: patient assessment and indications. Instr Course Lect. 2003;52:711-9.\u003c/li\u003e\n \u003cli\u003eGriffin DR, Parsons N, Mohtadi NG, Safran MR. A short version of the International Hip Outcome Tool (iHOT-12) for use in routine clinical practice. Arthroscopy. 2012;28(5):611-6; quiz 6\u0026ndash;8.\u003c/li\u003e\n \u003cli\u003eEbert JR, Raymond AC, Aujla RS, D\u0026apos;Alessandro P. The Effect of a Formal Nonoperative Management Program Combining a Hip Injection With Structured Adjunctive Exercise Rehabilitation in Patients With Symptomatic Femoroacetabular Impingement Syndrome. Am J Sports Med. 2023;51(3):694\u0026ndash;706.\u003c/li\u003e\n \u003cli\u003eReize P, M\u0026uuml;ller O, Motzny S, W\u0026uuml;lker N. [Prediction of the location of the center of rotation of the hip joint external landmarks]. Z Orthop Ihre Grenzgeb. 2006;144(5):492-6.\u003c/li\u003e\n \u003cli\u003eBrisson N, Lamontagne M, Kennedy M, Beaul\u0026eacute; P. The effects of cam femoroacetabular impingement corrective surgery on lower-extremity gait biomechanics. Gait Posture. 2013;37(2):258\u0026thinsp;\u0026minus;\u0026thinsp;63.\u003c/li\u003e\n \u003cli\u003eHunt M, Guenther J, Gilbart M. Kinematic and kinetic differences during walking in patients with and without symptomatic femoroacetabular impingement. Clinical biomechanics (Bristol, Avon). 2013;28(5):519\u0026thinsp;\u0026minus;\u0026thinsp;23.\u003c/li\u003e\n \u003cli\u003eLewis C, Khuu A, Loverro K. Gait Alterations in Femoroacetabular Impingement Syndrome Differ by Sex. J Orthop Sports Phys Ther. 2018;48(8):649\u0026thinsp;\u0026minus;\u0026thinsp;58.\u003c/li\u003e\n \u003cli\u003eNg K, Mantovani G, Modenese L, Beaul\u0026eacute; P, Lamontagne M. Altered Walking and Muscle Patterns Reduce Hip Contact Forces in Individuals With Symptomatic Cam Femoroacetabular Impingement. Am J Sports Med. 2018;46(11):2615-23.\u003c/li\u003e\n \u003cli\u003eDaenen B, Preidler K, Padmanabhan S, Brossmann J, Tyson R, Goodwin D, et al. Symptomatic herniation pits of the femoral neck: anatomic and clinical study. AJR Am J Roentgenol. 1997;168(1):149\u0026thinsp;\u0026minus;\u0026thinsp;53.\u003c/li\u003e\n \u003cli\u003eHewitt J, Guilak F, Glisson R, Vail T. Regional material properties of the human hip joint capsule ligaments. J Orthop Res. 2001;19(3):359\u0026thinsp;\u0026minus;\u0026thinsp;64.\u003c/li\u003e\n \u003cli\u003eHarris MD, Shepherd MC, Song K, Gaffney BMM, Hillen TJ, Harris-Hayes M, et al. The biomechanical disadvantage of dysplastic hips. J Orthop Res. 2022;40(6):1387-96.\u003c/li\u003e\n \u003cli\u003eHarris MD, MacWilliams BA, Bo Foreman K, Peters CL, Weiss JA, Anderson AE. Higher medially directed joint reaction forces are a characteristic of dysplastic hips: A comparative study using subject-specific musculoskeletal models. J Biomech. 2017;54:80\u0026thinsp;\u0026minus;\u0026thinsp;7.\u003c/li\u003e\n \u003cli\u003eHurd WJ, Snyder-Mackler L. Knee instability after acute ACL rupture affects movement patterns during the mid-stance phase of gait. J Orthop Res. 2007;25(10):1369-77.\u003c/li\u003e\n \u003cli\u003eZhu Y, Zhang S, Gao G, Wang H, Luan S, Wu K, et al. Concomitant Ipsilateral Knee Pain Is Associated With Worse Preoperative Functional Status and Short-Term Outcomes After Hip Arthroscopy in Patients With Femoroacetabular Impingement Syndrome. Arthroscopy. 2024;40(5):1490-9.\u003c/li\u003e\n \u003cli\u003eKennedy M, Lamontagne M, Beaul\u0026eacute; P. Femoroacetabular impingement alters hip and pelvic biomechanics during gait Walking biomechanics of FAI. Gait Posture. 2009;30(1):41\u0026thinsp;\u0026minus;\u0026thinsp;4.\u003c/li\u003e\n \u003cli\u003eRylander J, Shu B, Favre J, Safran M, Andriacchi T. Functional testing provides unique insights into the pathomechanics of femoroacetabular impingement and an objective basis for evaluating treatment outcome. J Orthop Res. 2013;31(9):1461-8.\u003c/li\u003e\n \u003cli\u003eCatelli D, Ng K, Kowalski E, Beaul\u0026eacute; P, Lamontagne M. Modified gait patterns due to cam FAI syndrome remain unchanged after surgery. Gait Posture. 2019;72:135\u0026thinsp;\u0026minus;\u0026thinsp;41.\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":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Femoroacetabular impingement syndrome, Biomechanics, Gait","lastPublishedDoi":"10.21203/rs.3.rs-5843084/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5843084/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe impact of femoroacetabular impingement syndrome (FAIS) on gait has been reported; however, no studies have documented the effects of Borderline Developmental Dysplasia of the Hip (BDDH) combined with FAIS on gait. This study aimed to evaluate the kinematic and kinetic abnormalities of the lower extremities in patients with combined FAIS and BDDH during level walking.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eA total of 42 participants were included, consisting of 14 patients with FAIS + BDDH, 14 with isolated FAIS and 14 healthy controls. Full-cycle kinematic and kinetic data were collected via motion capture and force plates. Gait analysis was performed in three planes (sagittal, coronal and transverse) for the hip, knee, ankle and pelvis joints. The range of motion (ROM), kinematics and kinetics were compared across the three groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCompared with isolated FAIS patients, FAIS + BDDH patients presented a significantly greater hip flexion angle during terminal stance and significantly smaller hip extension angles during preswing (P \u0026lt; 0.05). Moreover, the hip abduction moment was significantly reduced in the loading response and midstance phases in FAIS + BDDH patients (P \u0026lt; 0.05). The knee extension moment was significantly reduced during terminal stance in both FAIS groups (P \u0026lt; 0.05). The ankle dorsiflexion angle was significantly greater during midstance in FAIS + BDDH patients than in healthy controls, with concomitant reductions in the ankle dorsiflexion moment (P \u0026lt; 0.05). No significant differences were found in the range of motion (ROM) of the pelvis or hip joints among the three groups (P \u0026gt; 0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCompared with patients with isolated FAIS, patients with FAIS combined with BDDH exhibit a gait pattern characterized by biomechanical defects of the hip joint similar to developmental dysplasia of the hip (DDH), increased knee stiffness, and compensatory alterations in the ankle joint.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLevel of evidence:\u003c/strong\u003eV.\u003c/p\u003e","manuscriptTitle":"Three-dimensional lower limb kinematics and kinetics in femoroacetabular impingement syndrome (FAIS) patients with and without borderline developmental dysplasia of the hip (BDDH) during level walking","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-01-28 15:43:02","doi":"10.21203/rs.3.rs-5843084/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-01-24T11:43:49+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-01-24T10:34:09+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-01-24T10:31:44+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2025-01-16T15:17:09+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"10b0322f-d382-467f-a3cd-f0e6c5be4e8b","owner":[],"postedDate":"January 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-05-19T16:02:47+00:00","versionOfRecord":{"articleIdentity":"rs-5843084","link":"https://doi.org/10.1186/s12891-025-08727-4","journal":{"identity":"bmc-musculoskeletal-disorders","isVorOnly":false,"title":"BMC Musculoskeletal Disorders"},"publishedOn":"2025-05-16 15:58:11","publishedOnDateReadable":"May 16th, 2025"},"versionCreatedAt":"2025-01-28 15:43:02","video":"","vorDoi":"10.1186/s12891-025-08727-4","vorDoiUrl":"https://doi.org/10.1186/s12891-025-08727-4","workflowStages":[]},"version":"v1","identity":"rs-5843084","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5843084","identity":"rs-5843084","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}