Vitamin D supplementation for the management of knee osteoarthritis: a systematic review of randomized controlled trials

Conflicting evidence exists concerning the supplementation of vitamin D in knee osteoarthritis condition. This systematic literature review was done to explore the effects of vitamin D supplementation in the management of knee osteoarthritis. Electronic literature search was done in databases like PubMed®, Embase®, and Cochrane CENTRAL from inception to 6th July 2016. The quality of included Randomized Controlled Trials (RCTs) was assessed using Cochrane risk of bias tool. We considered change in Western Ontario and McMaster Universities (WOMAC) index, Visual Analog Scale (VAS) and Functional Pain Score (FPS) as the primary outcome measure. Change in tibial cartilage thickness, joint space width and safety profile was considered as secondary outcomes. Participants were randomized either to treatment or placebo group. Participants received cholecalciferol as an intervention through oral route in the dose range of 800–60,000 IU except in the one study where participants received ergocalciferol. All included RCTs showed a significant increase in serum vitamin D level in the treatment group compared to the placebo group at the end point. No significant reduction in pain and function was reported on WOMAC scale except in one study. No significant difference was reported for WOMAC stiffness in any study. VAS was assessed in three studies in which two showed statistically significant improvement in knee pain. Three of the RCTs reported safety data with one incidence of calculus ureteric and hip fracture found to be related to the drug. The study found evidence from RCTs to be insufficient to support the use of vitamin D supplementation for patients with knee osteoarthritis.