FP17.3 The influence of subject-specific gait pattern on computational models of contact stress in dysplastic hips

Abstract ICL17 - The Full Picture: Shaping the Future of Global Hip Preservation, Ground Floor Session Room (BMCC Level 0), October 9, 2026, 14:00 - 16:00 Objective Hip dysplasia often forces an individual to alter their gait pattern. However, computational modeling tools applied to quantify joint contact mechanics in hip dysplasia patients often model group-average hip loading patterns, even if considering patient-specific anatomy. The objective of this study was to determine the influence of individualized hip loading conditions derived from subject-specific gait analysis versus literature-based loading conditions on computationally derived contact stresses. Methods Discrete element analysis models [1] were created for 10 individuals with hip dysplasia (9F/1M; 26.6±7.8 years; LCEA 15.4°±5.0°) and used to calculate hip contact stresses using two different sets of loading conditions: (1) a literature-based average set of gait kinematics and joint reaction forces for a group of individuals with hip dysplasia [2], and (2) kinematics and forces from individualized gait analysis and musculoskeletal models. Individualized musculoskeletal models incorporated each subject’s 3D pelvis and femur reconstructions into the model with associated updated muscle origins and insertions. Results Average peak contact stress among all patients and across the whole stance phase of walking was not significantly different when modeling using the literature-based average gait (9.0±3.1 MPa) versus utilizing the subject-specific hip loading patterns (9.4±3.7 MPa). Average mean contact stress was also similar between approaches (1.1±0.4 MPa for literature-based; 1.3±0.5 MPa for subject-specific). However, despite this similarity in group averages, at some point in the gait cycle, each patient had peak contact stress underestimated by an average of 2.7±0.7 MPa when modeling using the literature-based gait, while also having peak contact stress overestimated by an average of 4.0±2.2 MPa when using the literature-based gait cycle. Contact stresses from subject-specific gait were significantly higher during early- to mid-stance than stresses from literature-based model loading. Conclusion Previous work has focused only on individualized anatomy, despite joint contact stress also depending on joint loading conditions. Subject-specific joint reaction forces and kinematics strongly affected the computed contact stress magnitudes and locations within the hip joint, highlighting the importance of incorporating the variability of individualized loading conditions into contact stress modeling. References [1] Aitken et al., J Orthop Res, 2022. [2] Harris et al. J Biomech, 2017.