Role of biomechanics and muscle activity in knee osteoarthritis structural disease progression

Surrogate measures of medial joint loading during walking are related to structural progression of knee osteoarthritis (OA). As muscle forces contribute to joint loading, muscle activation may influence OA disease course. Increased muscle co-contraction has been identified in individuals with knee instability and thus could be a compensatory mechanism. Although beneficial in the short term for joint protection, increased muscle co-contraction also elevates joint load and could underpin faster cartilage loss. We found that greater duration of medial muscle co-contraction and greater duration of medial relative to lateral co-contraction correlated positively with annual percent loss of medial tibial cartilage volume whereas lateral muscle co-contraction inversely correlated with cartilage loss. Others have found more prolonged lateral muscle activity during gait at baseline in people who showed structural progression. Whilst further research is clearly needed, evidence supports the role of altered gait biomechanics and muscle activity in OA progression.