Preoperative hip abductor strength predicts discharge destination after total hip arthroplasty

Purpose: This study aimed to clarify the association between preoperative physical function and discharge destination after total hip arthroplasty (THA).

Methods: This retrospective study included patients who underwent primary unilateral THA for hip osteoarthritis. Preoperative physical function was assessed via maximal isometric muscle strength (hip abduction and knee extension) and comfortable walking speed. The patients were divided into two groups according to the discharge destination (home or transfer to other facilities). Multivariate logistic regression analysis was used to identify preoperative physical function associated with discharge destination.

Results: Of the 174 patients, 120 were discharged directly to home, and 54 were transferred to other facilities. Those transferred to other facilities were significantly older, more likely to live alone, and had a longer operation time. In addition, they demonstrated lower hip abductor strength on both sides and lower knee extensor strength on the operative side. Multivariate logistic regression analysis revealed that hip abductor strength on both sides, not knee extensor strength, was independently associated with the discharge destination. The largest area under the receiver operating characteristic curve was 0.668 for the hip abductor strength of the contralateral side. The optimal cutoff point was revealed to be 0.035 kgf·m/kg and 0.031 kgf·m/kg for the operative and contralateral sides, respectively.

Conclusions: Preoperative hip abductor strength, particularly on the contralateral side with a cutoff value of 0.031 kgf·m/kg, could be a predictor of discharge destination after unilateral THA. Our findings would be useful in planning rehabilitation programs.