Sarcopenia and cognitive impairment after hip fracture in older adults: a narrative review and conceptual rehabilitation framework.

Hip fracture in later life is followed by high mortality, incomplete recovery of mobility, and frequent loss of independence. Sarcopenia and cognitive impairment are common at presentation yet are often assessed and treated as separate determinants of recovery. This narrative review synthesizes evidence on their joint clinical impact, plausible links, and rehabilitation implications. In a 2025 rehabilitation cohort, independent ambulation was recovered by 60.8% of participants with both conditions versus 90.2% with neither; the combined phenotype was associated with a 57% lower likelihood of walking recovery. Recent studies also associate sarcopenia with postoperative delirium and early postoperative cognitive decline, whereas cognitive impairment is linked to more complications, less rehabilitation referral, and poorer function. Mechanistic translation remains incomplete: the FNDC5/irisin-BDNF axis has not been shown to mediate recovery in hip-fracture cohorts because target engagement, biomarker source, assay comparability, and perioperative confounding remain unresolved. We therefore propose an evidence-informed, phase-specific conceptual framework incorporating orthogeriatric assessment, delirium prevention, progressive resistance and task-specific exercise, individualized protein-energy support, cognitively adapted communication and motor learning, management of concerns about falling, and supported continuity after discharge. The framework integrates components supported by hip-fracture studies with recommendations extrapolated from broader geriatric guidance; it has not been validated as a complete care pathway for the combined phenotype. Future trials should include people with cognitive impairment, standardize sarcopenia definitions, measure rehabilitation exposure and adherence, and test whether targeting the combined phenotype improves patient-centered outcomes.