Predictors of independent ambulation at discharge following hip fracture surgery: A focus on the relative contribution of skeletal muscle mass and cognitive function.

BACKGROUND: Skeletal muscle mass is often associated with long-term outcomes, but its specific influence on short-term recovery, such as walking ability at discharge, remains unclear. This study aimed to determine whether preoperative skeletal muscle mass or other clinical factors, including cognitive function, serve as stronger predictors of early functional recovery after hip fracture surgery. METHODS: We retrospectively analyzed 350 patients with proximal femoral fractures who were ambulatory before surgery. Skeletal muscle mass was assessed using the psoas muscle index measured on preoperative computed tomography. The relative contributions of muscle mass, cognitive function, and pre-fracture mobility to walking ability at discharge, defined as independent ambulation on all surfaces, were evaluated. RESULTS: Reduced psoas muscle index was observed in 36% of patients. Multivariate analysis showed that younger age, better pre-fracture mobility, and higher cognitive function scores were independent predictors of independent ambulation at discharge, whereas psoas muscle index status was not associated with this outcome. The influence of age, cognitive function, and pre-fracture mobility clearly exceeded that of baseline muscle quantity. CONCLUSIONS: Early ambulation after hip fracture surgery is determined primarily by age, cognitive function, and pre-fracture functional status rather than baseline skeletal muscle mass. These findings indicate that patients with low muscle mass can still achieve independent walking when cognitive and functional reserves are preserved, underscoring the importance of multidisciplinary rehabilitation tailored to cognitive status and age-related needs.