Not only muscle mass but also muscle quality is associated with knee extension muscle strength in patients with hip fractures

Abstract

This study aimed to assess the relationship between isometric knee extension muscle strength on the operated or nonoperated sides and PhA in patients with hip fractures at approximately 6months postoperatively. This study was a cross-sectional study. Skeletal muscle index (SMI), PhA, knee extension muscle strength on the operated and nonoperated sides, and other physical function variables were assessed at approximately 6months postoperatively. To identify predictors of knee extension muscle strength on the operated and nonoperated sides, hierarchical multiple regression analysis was performed. A total of 90 patients with hip fractures were included (mean age, 80.1 ± 6.9years). SMI (0.45) and PhA on the operated side (0.27) were the significant associated factors extracted for isometric knee extension muscle strength on the operated side (standardized partial regression coefficients), independent of age, sex, and body mass index (BMI). Movement control during one-leg standing on the nonoperated side (0.26), SMI (0.32), and PhA on the nonoperated side (0.40) were the significant associated factors extracted for isometric knee extension muscle strength on the nonoperated side, independent of age, sex and BMI. Our results revealed that the decrease in isometric knee extension muscle strength on the operated and nonoperated sides in patients with hip fractures at approximately 6months postoperatively was associated with not only a decrease in skeletal muscle mass but also a decrease in muscle quality, characterized by a decreased PhA.