Dynamic knee loading is related to cartilage defects and tibial plateau bone area in medial knee osteoarthritis

Objective: To evaluate the relationship between dynamic mechanical loading, as indicated by external knee adduction moment (KAM) measures during walking, and measures of articular cartilage morphology and subchondral bone size in people with medial knee osteoarthritis (OA). Design: 180 individuals with radiographic medial tibiofemoral OA participated. Peak KAM and KAM angular impulse were measured by walking gait analysis. Tibial cartilage volume and plateau bone area, and tibiofemoral cartilage defects were determined from magnetic resonance imaging using validated methods. Results: Both peak KAM (coefficient = 0.42, 95% confidence interval (Cl) 0.04-0.79, P=0.03) and KAM impulse (coefficient = 1.79, 95% Cl 0.80-2.78, P<0.001) were positively associated with the severity of medial tibiofemoral cartilage defects. KAM impulse was also associated with the prevalence of medial tibiofemoral cartilage defects (odds ratio 4.78, 95% CI 1.10-20.76, P=0.04). Peak KAM (B=0.05, 95% Cl 0.01-0.09, P=0.02) and KAM impulse (B=0.16, 95% CI 0.06-0.25, P=0.002) were positively associated with medial:lateral tibial plateau bone area, and KAM impulse was also associated with medial tibial plateau bone area (B=133.7, 95% CI 4.0-263.3, P=0.04). There was no significant association between KAM measures and tibial cartilage volume. Conclusion: Peak KAM and KAM impulse are associated with cartilage defects and subchondral bone area in patients with medial knee OA, suggesting that increased mechanical loading may play a role in the pathological changes in articular cartilage and subchondral bone that occur with medial knee OA. (C) 2010 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.