The study aimed to examine whether the improvement in gait function after total knee arthroplasty (TKA) correlated with the amount of physical activity and whether both gait self-efficacy and gait function are predictors of the amount of physical activity up to 6 months after surgery.
Eighty-one patients were tested preoperatively and at the first and sixth postoperative months after TKA. Physical performance (timed up and go [TUG], sit to stand, muscle strength) and the modified gait efficacy scale scores were evaluated. The average amount of physical activity during the 6 postoperative months was measured with a pedometer with triaxial accelerometer. Stepwise multiple regression analyses were performed using TUG changes and postoperative physical activity. The discriminative properties of physical activity for improvement in gait function were subsequently investigated by applying a receiver operating characteristic curve analysis.
The multiple regression analyses indicated that the amount of physical activity and the improvement in sit-to-stand time were important in predicting improvement in TUG scores after TKA, and postoperative physical activity up to 6 months was predicted by the modified gait efficacy scale and TUG scores at the first postoperative month. The receiver operating characteristic curve analysis suggests that with a cutoff point of 3053 steps/d, the amount of physical activity may be a good predictive factor for gait function after TKA.
The clinical implications are that increases in physical activity can promote improvement in gait function after TKA and present with a solid numerical target for the recommended amount of physical activity.