Knee joint moment changes and the relationship to radiological severity and body weight following a structured education and exercise therapy intervention for knee osteoarthritis

Background: Evidence links knee joint loads to knee osteoarthritis progression, making load reduction a target for non-surgical interventions. Exercise therapy does not appear to reduce knee joint moments, but studies focus on the medial compartment, overlook severity in other compartments and the influence of body weight, and do not assess more demanding tasks. This study evaluated whether knee adduction and knee flexion moments decrease following exercise therapy. We examined the extent to which knee joint moments change during a more demanding task, chair-rise, and the influence of body weight and osteoarthritis compartment severity. Methods: Thirty-one participants with knee osteoarthritis underwent three-dimensional biomechanical analysis during walking and chair rises at baseline and week-8 after the Good Life with OsteoArthritis in Denmark intervention. Multilevel models estimated knee adduction and knee flexion moments and their relationships with osteoarthritis compartment severity and body weight. Findings: Both knee adduction and knee flexion moments reduced during chair-rise after the intervention. The first peak knee adduction moment increased slightly by 3 % from 41.7 Nm (90 % CrI 37.0, 46.5) to 43.0 Nm (38.5, 47.5) during walking, regardless of osteoarthritis compartment severity. Greater lateral and patellofemoral compartment severity was related to larger knee flexion moment reductions during walking and chair-rises. Weak relationships were found between body weight and knee adduction and knee flexion moments for both tasks. Following the intervention, heavier people had larger increases during walking, but this was uncertain. Interpretation: Intervention had minimal impact on the knee adduction moment during walking, regardless of compartment severity. Reductions in knee joint moments were observed during chair-rises. Changes in joint load following exercise therapy may be more apparent during demanding tasks. The relationship between knee flexion moment and joint load during demanding tasks warrants further investigation.