Author(s): HANSEN, L., EBBECKE, J., NAECKEL, N., VIELLEHNER, J., POTTHAST, W., Institution: GERMAN SPORT UNIVERSITY COLOGNE, Country: GERMANY, Abstract-ID: 2173

INTRODUCTION:
Knee osteoarthritis (KOA) is associated with altered gait mechanics, including increased trunk lean, elevated hip flexion moments, and greater hamstring activity, understood as compensatory strategies to unload the knee. However, most evidence comes from cohorts with reduced functional capacity, making it unclear whether these adaptations reflect disease pathology or deconditioning. We aimed to determine whether the previously reported mechanistic chain of trunk-hip-hamstring adaptations persist in a physically active KOA cohort, and to compare their magnitude relative to young and elderly controls.
METHODS:
Fifty-six participants (19 KOA (Kellgren-Lawrence ≥ 2, 40-65 yrs), 18 age-matched controls (CO, 40-65 yrs), 19 young controls (CY, 18-30 yrs)) conducted multiple trials of overground walking (1.4 m/s) and running (3.0 m/s). Eligibility criteria included male or female recreational or competitive athletes who were physically active (sportive cycling > 1 x per week, > 3000 km/year). Three-dimensional kinematics and kinetics were recorded using marker-based motion capture, muscle activity was recorded using unilateral 8-channel surface electromyography. Inverse kinematics and dynamics calculations were carried out using musculoskeletal modeling in OpenSim 4.5. Hip flexion moments and MVC-normalized biceps femoris activation profiles were quantified across the stance phase using statistical parametric mapping. Group differences were assessed using a mixed-model SPM ANOVA. Effect magnitudes and waveform patterns were examined to evaluate consistency with previously reported compensatory mechanisms. Significance threshold across tests was set to alpha = 0.05.
RESULTS:
Waveform patterns in the KOA group followed previously reported directional trends during gait and running, including elevated hip flexion moments and increased biceps femoris activity. The main effect on group affiliation did not reach significance (F(2,52); z_peak = 6.03; z* = 6.58 with alpha = 0.05), nor did the interaction effect (F(2,52); z_peak = 4.14; z* = 6.58). Two suprathreshold clusters for the main effect on the factor “task” were observed from 0% - 7% stance phase (p = 0.02) and 8% - 99% stance phase (p < 0.001).
CONCLUSION:
These findings indicate that neuromechanical adaptations associated with KOA are not inevitable consequences of joint degeneration but are influenced by functional capacity. The attenuation of trunk-hip compensation and hamstring demand in physically active KOA participants suggests that preserved neuromuscular function may limit the development of secondary gait adaptations. This adds a capacity-dependent compensation aspect to the commonly pathology-dominated perspective on KOA gait biomechanics, with implications for rehabilitation strategies and the interpretation of locomotion data in KOA cohorts.