Vitamin D Deficiency in Hip Fracture Patients: Outcome-Specific Associations and Post-Fracture Management-A Narrative Review.

Background and Objectives: Vitamin D deficiency is common in older adults with hip fracture and has been associated with adverse postoperative outcomes. However, heterogeneity in deficiency thresholds, outcome definitions, and patient populations has complicated the interpretation and clinical application of existing evidence. This narrative review aimed to summarize current evidence regarding perioperative vitamin D status, its associations with postoperative complications, mortality, functional recovery, and secondary fracture, and the role of vitamin D supplementation after hip fracture. Materials and Methods: Relevant studies were identified through PubMed searches and manual screening of reference lists. Cohort studies, randomized controlled trials, systematic reviews, meta-analyses, and clinical guidelines addressing vitamin D status, supplementation, hip fracture outcomes, fracture prevention, or postoperative recovery in older adults were narratively synthesized. Results: Low serum 25-hydroxyvitamin D was associated with selected early medical complications, mortality, impaired functional recovery, and secondary hip fracture, although these associations varied across outcomes. The strongest prognostic associations with mobility were observed in patients with severe deficiency (approximately ≤10-12 ng/mL), whereas mild insufficiency showed less consistent associations. Heterogeneity among studies reflected differences in deficiency thresholds, sampling timing, outcome definitions, follow-up duration, study populations, and adjustment for frailty and comorbidity. Vitamin D supplementation consistently increased serum 25-hydroxyvitamin D concentrations but did not consistently improve gait, postoperative complications, mortality, or recurrent fracture. Favorable outcomes reported with exercise- and nutrition-based multimodal interventions could not be attributed to vitamin D supplementation alone. Conclusions: Vitamin D deficiency should be interpreted within the broader context of frailty, nutritional status, muscle function, and skeletal health after hip fracture. Vitamin D assessment and correction should be integrated into comprehensive post-fracture care alongside osteoporosis treatment, adequate calcium and protein intake, rehabilitation, and fall prevention. However, clinical benefits of supplementation beyond correction of deficiency remain uncertain, and future studies should focus on patients with severe deficiency and clinically meaningful, patient-centered outcomes.