Integrated rehabilitation and ambulatory recovery in older adults with hip fracture according to muscle strength and sarcopenia status: a secondary analysis of a randomized controlled trial

Purpose Sarcopenia and impaired muscle strength are common in older adults with hip fracture and are strongly associated with poor functional recovery. Although integrated multidisciplinary rehabilitation improves outcomes after hip fractures, it remains unclear whether its benefits over conventional rehabilitation differ by baseline muscle strength or sarcopenia severity. This study aimed to examine whether the functional benefits of Fragility Fracture Integrated Rehabilitation Management (FIRM) vary according to sarcopenia status and handgrip strength (HGS) in older adults after hip fracture surgery. Methods This was a secondary analysis of a multicenter randomized controlled trial comparing FIRM with conventional rehabilitation in adults aged ≥ 65 years undergoing hip fracture surgery. Independent ambulation at 12 months was the primary outcome. Sarcopenia was classified using three approaches: sarcopenia versus non-sarcopenia, a three-level classification (non-sarcopenia, possible sarcopenia, sarcopenia), and low versus normal HGS. Logistic regression models including treatment, sarcopenia status, and their interaction, were fitted with sequential adjustment for relevant covariates. Results Of the 203 randomized participants, 119 (58.6%) completed the 12-month follow-up. Although treatment-by-sarcopenia interactions were not statistically significant, stratum-specific analyses consistently showed a greater benefit of FIRM in participants with sarcopenia or low HGS. In the fully adjusted models, FIRM was associated with large absolute improvements in independent ambulation among participants with sarcopenia (odds ratio [OR], 4.01; risk difference [RD] + 32.3%) and low HGS (OR, 4.38; RD + 35.3%). Conclusions Integrated rehabilitation provides greater functional benefit than conventional rehabilitation in older adults with sarcopenia or low muscle strength after hip fracture.