Impact of skeletal muscle mass on early joint function after total hip arthroplasty: report of 107 cases

Objective To explore the effect of skeletal muscle mass on the outcomes of early joint function in patients undergoing total hip arthroplasty. Methods A prospective study was performed on 107 patients who planned to undergo hip arthroplasty for the first time from November 2020 to December 2021 in Army Medical Center of PLA. The demographic data was collected, and nutritional status and pain status were assessed. Skeletal muscle mass was measured by bioelectrical impedance analysis (BIA), and was corrected to the skeletal muscle mass index (SMI) with their height. With follow-up call, the joint function was assessed with Harris Hip Score Scale, and daily living activities was investigated with Activities of Daily Living(ADL) Scale at 1, 3 and 6 months after surgery. The effect of SMI on early rehabilitation after hip arthroplasty was analyzed. According to the diagnostic criteria of the Asian Sarcopenia Working Group 2019, the patients were divided into normal SMI group and reduced SMI group, and postoperative rehabilitation was compared between the 2 groups. Results Pearson correlation analysis showed that SMI was positively correlated with postoperative Harris score and ADL score. Multivariate linear regression model showed that SMI was an influencing factor of Harris score and of ADL score in different periods after surgery, with a standardized regression coefficient of 0.394~0.436 and 0.391~0.461 (P < 0.01), respectively. The incidence of SMI reduction in total hip arthroplasty was 32.71%. The SMI reduction group had significantly larger ratio of needing walk aid instrument for 30 d, but lower postoperative Harris scores and ADL scores when compared with the normal SMI group (all P < 0.01). Conclusion The preoperative SMI of patients undergoing hip arthroplasty independently affects the outcomes of early joint function, and the patients with reduced SMI are the focus population of clinical rehabilitation care.