Distinct hip–knee coordination patterns in individuals with hip osteoarthritis as measured by cyclograms

Background: Hip osteoarthritis (HOA), involving cartilage degeneration and altered load distribution, disrupts gait biomechanics. While joint coordination plays a key role in efficient walking, dynamic inter-joint coordination changes across HOA progression remain underexplored. Research question: Do inter-joint coordination patterns differ between healthy individuals and those with HOA? How does HOA severity affect inter-joint coordination, as analysed through hip-knee cyclograms and coupling angles? Methods: Using a publicly available dataset, we analyzed 78 healthy individuals and 96 HOA participants, categorized into three subgroups based on Kellgren–Lawrence (KL) grade. The inter-joint coordination outcome measures included cyclograms perimeter, area, and coupling angle. ANCOVA (covariates: walking speed/weight/BMI) was conducted to examine differences in cyclogram area/perimeter between groups, while MANCOVA was performed to analyse differences in inter-joint coordination patterns between groups. Post-hoc comparison tests were performed where overall significance was observed using multiple t tests. Results: Cyclogram area, perimeter, and coupling angle differed significantly between healthy and HOA groups (all p < 0.001), but not among HOA severity subgroups. Healthy individuals showed in-phase coordination pattern during mid-stance, whereas individuals with HOA displayed proximal coordination. In individuals with HOA, the coordination pattern shifted from proximal to anti-phase earlier than in healthy individuals during terminal stance and early pre-swing. No significant difference in coordination pattern during the swing phase was observed between healthy individuals and individuals with HOA. Significance: Hip-knee coordination patterns may serve as a biomechanical marker of HOA-related gait dysfunction, offering a potential avenue for prompt intervention and management of the disease.