Identifying the modification factors of exercise therapy on biomechanical load in patients with knee osteoarthritis: A systematic review and meta-analysis

Objective As the progression of knee osteoarthritis (OA) is associated with large biomechanical loads, an optimally designed intervention is needed to prevent disease progression and symptoms. We aimed to investigate the effect of exercise therapy—the gold standard intervention—on biomechanical loads in patients with knee OA and identify its modification factors. Design Systematic review and meta-analysis Data sources PubMed, PEDro, and CINAHL; from study inception to May 2021 Eligibility criteria Studies evaluating the first peak knee adduction moment (KAM), peak knee flexion moment (KFM), maximal knee joint compression force (KCF), or co-contraction during walking before and after exercise therapy in patients with knee OA Risk of Bias PEDro scale and NIH scale. Results Among 11 RCTs and nine non-RCTs, 1100 patients with knee OA were included. First peak KAM (SMD 0.11; 95% CI: -0.03–0.24), peak KFM (SMD 0.13; 95% CI: -0.03–0.29), and maximal KCF (SMD 0.09; 95% CI -0.05–0.22) tended to increase. An increased first peak KAM was significantly associated with a larger improvement in knee muscle strength and WOMAC pain. The quality of evidence regarding the biomechanical loads was low-to-moderate according to the GRADE approach. Conclusions Exercise therapy tends to increase biomechanical loads. The improvement in pain and knee muscle strength may mediate the increase in first peak KAM, suggesting difficulty in balancing symptom relief and biomechanical load reduction. Therefore, exercise therapy may satisfy both aspects simultaneously when combined with biomechanical interventions, such as a valgus knee brace or insoles. Funding Grant-in-Aid for JSPS Research Fellows, 19J23020. Registration PROSPERO (CRD42021230966)