Contralateral cane use and knee joint load in people with medial knee osteoarthritis: the effect of varying body weight support.

Objective: To evaluate the effect of varying body weight support (BWS) with contralateral cane use on medial knee load, measured by external knee adduction moment (KAM), in medial knee osteoarthritis (OA) participants. Influences of cane use technique, pain and malalignment on the cane's load-reducing effects were investigated.

Methods: Participants (n=23) underwent three-dimensional gait analysis to measure KAM peaks (early and late stance) and impulse. Unaided walking was firstly analyzed. Following cane use training, participants placed pre-determined magnitudes of BWS through the cane (10%, 15% and 20% in random order), with visual feedback provided via a force-instrumented cane and projection screen. Contributions of cane use technique (peak BWS magnitude and timing, cane impulse (BWS∗time) anterior and lateral cane distance from limb) and Western Ontario McMaster Universities OA Index (WOMAC) pain and malalignment to KAM outcomes were evaluated using linear mixed models.

Results: Cane use reduced all KAM variables, with a dose-response effect apparent. Cane BWS impulse was important in reducing the early stance peak KAM (P<0.001), peak BWS for late stance KAM (P<0.001) and both BWS measures for KAM impulse reductions (P<0.001). Variables contributing to efficacy of load-reduction differed across outcomes. Generally, greater reductions were achieved with longer lateral cane distances, peak BWS timing similar to KAM peaks, and shorter anterior cane distances. Greater pain and varus alignment improved load-reduction for some outcomes.

Conclusions: Contralateral cane use significantly reduced medial knee load, with a dose-response effect. Medial knee OA patients should be encouraged to maintain greater BWS across stance, with cane placement more lateral for optimum benefit.