Kinetic effects of unicompartmental unloader braces in medial knee osteoarthritis: A longitudinal study of joint load during level, stair, and slope walking

Knee osteoarthritis (KOA) impairs mobility, particularly in higher demanding tasks like stair climbing and slope walking. While unloader braces are well-studied for level walking (LVL), their effects on more complex locomotion tasks remain underexplored. This study analyzes how unloader braces influence knee joint kinetics and load distribution over various demanding tasks. Twenty participants with medial KOA were assessed at baseline (BAS) and after six weeks (FU) of using a valgus unloader brace. Musculoskeletal modeling was used in conjunction with a multifaceted statistical approach to investigate kinetic effects and load changes across locomotion tasks. Mixed-effects modeling analyzed overall trends, including main effects (locomotion tasks, time and braced vs. unbraced conditions) and their interactions. ANOVA with statistical parametric mapping (SPM) offered detailed insights into variations related to the brace or time throughout the stance phase for each locomotion task. ANOVA with SPM showed significant reductions in knee adduction moment (KAM) and medial compartment force (M-CF) across all tasks, with larger effect sizes during slope walking and stair climbing. Lateral compartment force (L-CF) increased during LVL and most higher-demanding tasks. FU values were generally lower than BAS, though inconsistently. Mixed-effects modeling found no significant main or interaction effects, likely due to its broader scope and increased variability from aggregated data and multiple interactions. While this study addresses a critical literature gap and provides valuable mid-term insights, longer-term studies with larger sample sizes are required to validate these findings and improve statistical power for detecting main and overarching trends.