Knee osteoarthritis (OA) is the most common joint disorder in elderly individuals, with a prevalence of 10% in men and 13% in women ages 60 years or older. This knee OA will eventually will go on to have a total knee replacement. Therefore this meta analysis suggested vitamin D supplementation,  a cost-effectiveness approach to prevent the progression of knee OA. 

To present data about the impact of vitamin D supplementation on symptomatic knee osteoarthritis (OA).

A systematic review and meta-analysis were performed to pool the results from randomised clinical trials quantitatively. MEDLINE,  Web of Science, conference abstracts, reference lists of identified studies,  Embase, and ClinicalTrials.gov were searched to collect the data. Assessment of effect sizes were done by applying a standardised mean difference (SMD). Fixed-effects or random-effects models were employed to pool outcomes depending on the degree of heterogeneity. 

A total of four clinical trials comprising 560 subjects in the placebo group and  570 subjects in the vitamin D supplementation group were selected. All of the selected studies were of high quality and low risk of bias. According to the outcomes, vitamin D supplementation had a statistically notable but small-to-moderate impact on pain control among the patients with knee OA. Although, no effects were noticed for the joint space width or change in tibial cartilage volume. Further, as per the subgroup analysis, vitamin D showed no notable impact regardless of whether patients had enough or inadequate serum 25(OH) D levels at baseline.

Vitamin D supplementation may not have a clinically notable influence on structure progression or pain management within participants with knee OA. Longer-term clinical trials with the correct judgment of symptom and radiologic changes are needed to further elucidate the influence of vitamin D supplementation among individuals with symptomatic knee OA and low serum 25(OH)D levels.