Relationship between Trunk Muscle Mass Index at Admission and Walking Independence in Patients with Hip Fracture

OBJECTIVES: This study aimed to investigate the relationship between trunk muscle mass index (TMI), appendicular skeletal muscle mass index (ASMI), and walking independence in patients aged 65 years and older undergoing rehabilitation for hip fracture. METHODS: This retrospective, observational study was conducted in a convalescent rehabilitation ward and included 314 patients (aged ≥65 years) with hip fracture. The patients were classified into the independence group [functional independence measure (FIM)-walk score ≥6] or the non-independence group (FIM-walk score ≤5) according to the mobility item score among the motor FIM items at the time of discharge. Age, sex, TMI, ASMI, and Mini Nutritional Assessment-Short Form (MNA-SF) data were also extracted. Between-group and multivariate analyses were performed to evaluate the factors associated with walking independence. RESULTS: The independence group had higher TMI (males: 6.6±0.9 vs. 5.6±1.0 kg/m(2), P <0.001; females: 6.1±0.8 vs. 5.7±1.0 kg/m(2), P <0.001), ASMI (males: 6.7±1.1 vs. 5.9±1.3 kg/m(2), P=0.004; females: 5.3±0.9 vs. 4.7±0.8 kg/m(2), P <0.001), MMSE-J (21.5±4.9 vs. 16.4±4.5 points, P <0.001), and MNA-SF [median (interquartile range): 8 (6–9) vs. 7 (5–8) points, P <0.001] than the non-independence group. Multivariate analysis showed that TMI at admission was significantly associated with walking independence (odds ratio: 1.86, 95% confidence interval: 1.28–2.72, P <0.001). CONCLUSIONS: This study suggests that a higher TMI at admission was important for acquiring walking independence in patients with hip fracture and shows the importance of early evaluation of TMI during hospitalization of patients with hip fracture.