To provide evidence on the effects of vitamin D supplementation on knee osteoarthritis (KOA) and new targets for clinical prevention and treatment of KOA.
The PubMed, Embase, Web of science, Wanfang, CNKI and SinoMed databases were retrieved to investigate the effects of vitamin D supplementation on patients with KOA. The search time was from databases establishment to 15 November 2020. RevMan5.3 software was used for meta-analysis. The results were expressed as standardized mean difference (SMD) with 95% confidence interval (CI) or weighted mean difference (WMD) with 95% confidence interval (CI).
A total of 1599 patients with osteoarthritis of the knee were included in the study, which involved six articles. The results of the meta-analysis showed that vitamin D supplementation is statistically significant for WOMAC score (SMD = - 0.67, 95% CI – 1.23 to – 0.12) in patients with KOA, including WOMAC pain score (SMD = - 0.32, 95% CI – 0.63 to – 0.02), function score (SMD = - 0.34, 95% CI – 0.60 to – 0.08) and stiffness score (SMD = - 0.13, 95% CI – 0.26 to – 0.01). In subgroup analysis, vitamin D supplementation less than 2000 IU was statistically significant for the reduction of stiffness score (SMD = - 0.22, 95% CI – 0.40 to – 0.04). Vitamin D supplements can reduce synovial fluid volume progression in patients with KOA (SMD = - 0.20, 95% CI – 0.39 to – 0.02). There was no statistical significance in improving tibia cartilage volume (SMD = 0.12, 95% CI – 0.05 to 0.29), joint space width (SMD = - 0.10, 95% CI – 0.26 to 0.05) and bone marrow lesions (SMD = 0.03, 95% CI – 0.26 to 0.31).
Vitamin D supplements can improve WOMAC pain and function in patients with KOA. But there is a lack of strong evidence that vitamin D supplementation can prevent structural progression in patients with KOA.