Zhang H, et al. - Researchers assessed the prognostic value of vitamin D status in patients undergoing knee or hip surgery. They performed a meta-analysis of 12 studies (2,593 patients; age 69.89 years [95% CI 68.07–71.70]; 35.95% [29.43–42.46] males). These studies were identified via a literature search in electronic databases. The selection process was based on predetermined eligibility criteria. They found a high prevalence of hypovitaminosis D in osteoarthritis patients undergoing knee or hip surgery. They infer that vitamin D deficiency may influence the outcomes of orthopedic joint surgery.