Association between Quadriceps Muscle Strength and the Forgotten Joint Score after Total Hip Arthroplasty

Total hip arthroplasty (THA) effectively enhances hip function and alleviates pain in patients who have osteoarthritis, improving their quality of life. The Forgotten Joint Score-12 (FJS-12), a patient-reported outcome measure, has recently gained attention as a method for assessing joint awareness during daily activities following THA; however, the association between muscle strength, specifically quadriceps muscle strength, and the FJS-12 has not been fully investigated.

This cross-sectional study involved 624 patients who underwent THA at a single center in Japan. The mean patient age was 67 years (range, 43 to 94), and 85.3% of the cohort were women. We aimed to investigate the association between quadriceps muscle strength and the FJS-12 (measured at 12 months postoperatively) using multiple regression analyses adjusted for variables such as pain and leg length discrepancy.

The mean FJS-12 was 72.2, and the mean quadriceps muscle strength was 1.2 Nm/kg. Higher quadriceps muscle strength was significantly associated with better FJS-12 outcomes (β = 0.28, P < 0.001). Conversely, increased pain and perceived leg length discrepancy were negatively associated with lower FJS-12 values.

Our findings indicate that quadriceps muscle strength is a crucial determinant of joint awareness as measured using the FJS-12 in patients undergoing THA. These results highlight the potential benefits of targeted rehabilitation to enhance quadriceps muscle strength, which may help patients undergoing THA experience less joint awareness in their daily activities.