High-impact physical activity participation and 12-month risk of joint replacement: a longitudinal mediation analysis of 17 661 patients with knee or hip osteoarthritis.

OBJECTIVE

Clinical guidelines consistently recommend low-impact physical activity (PA) for the management of hip or knee osteoarthritis (OA). This study aimed to determine the risk and mediators of joint replacement in people with hip or knee OA who participate in high-impact PA.

METHODS

We conducted a mediation analysis using data from the Good Life with osteoArthritis in Denmark (GLA:D) registry. Baseline PA was self-reported using the University of California, Los Angeles (UCLA) Activity Scale and categorised as high-impact, high-intensity, moderate-intensity or low-intensity. Outcomes were self-reported total hip replacement (THR) or total knee replacement (TKR) at 12 months. Candidate mediators measured at 3 months were joint pain intensity, functional capacity (30-second chair stand test) and fear of joint damage from PA.

RESULTS

Among 5911 participants with hip OA (66.8 years, 69.5% women), 5.9% engaged in high-impact PA. Among 11 750 participants with knee OA (66.5 years, 72.7% women), 5.2% engaged in high-impact PA. High-impact PA was associated with 36-48% lower odds of THR and was not associated with altered risk of TKR. There was little evidence that pain intensity, functional capacity or fear of joint damage mediated these associations. However, a small indirect effect via functional capacity was observed, where a greater functional capacity was associated with a reduction in odds of TKR (OR 0.92, 95% CI 0.87 to 0.98).

CONCLUSION

High-impact PA was associated with a substantially lower risk of THR, and did not increase TKR risk. Clinicians may consider recommending higher-impact activities for individuals with hip OA, and supporting continued participation in knee OA when symptoms, capacity and patient goals allow.