Title : Vitamin D status and supplementation in orthopaedic trauma: A systematic review and meta-analysis of fracture union, infection, and functional outcomes
Abstract:
Background: Vitamin D deficiency is biologically plausible as a modifiable risk factor across orthopaedic trauma outcomes, yet no comprehensive synthesis has examined prevalence, fracture healing, infection, and prevention within a unified framework.
Methods: A systematic review and meta-analysis was conducted following PRISMA 2020 guidelines (PROSPERO: CRD420261380380). PubMed, MEDLINE via ovid, embase, and central were searched from inception to april 2026. Adults with orthopaedic trauma were eligible. Randomised trials were assessed using cochrane RoB 2 and observational studies using the New Castle-Ottawa Scale(NCOS). Meta-analysis was performed for fracture prevention using random-effects inverse-variance weighting; remaining domains were narratively synthesised owing to clinical and methodological heterogeneity.
Results: Twenty-three primary studies (N = 396,502 participants) were included across four domains,with four contextual studies retained for interpretation. Prevalence studies reported combined vitamin D deficiency and insufficiency in 43–86% of orthopaedic patients at presentation. Dark skin pigmentation (OR ~5.5), winter presentation, and obesity were the most consistent independent risk factors. In fracture healing, persistent deficiency was independently associated with delayed union in observational studies (9.7% vs. 0.3% in patients remaining deficient versus sufficient after supplementation; population-level OR 1.14, 95% CI 1.05–1.22). The only randomised trial was underpowered and negative. In infection, five of seven observational studies reported significantly lower 25 hydroxyvitamin D concentrations in infected patients (strongest effect estimate OR 5.94). However, acute inflammation suppresses hydroxyvitamin D perioperatively, critically undermining causal interpretation.Meta analysis of four fracture-prevention RCTs yielded a pooled HR of 0.83 (95% CI 0.73–0.94; I²=45%); sensitivity analysis restricted to trialsachieving ≥ 800IU/day yielded HR 0.75 (95% CI 0.64–0.88), suggesting a clinically significant dose-response threshold.
Conclusion: Vitamin D deficiency is common in orthopaedic trauma and associated with adverse outcomes. Supplementation at ≥ 800 IU/day reduces fracture incidence in vitamin-D-depleted elderly patients. Evidence for healing and infection remains observational.
