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) ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was supported by a Grant-in-Aid for JSPS Research Fellows (grant number: 19J23020). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: N/A I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present work are contained in the manuscript