Five randomized controlled trials were included in this meta-analysis which sought to investigate the efficacy of mesenchymal stem cell injections in patients with knee osteoarthritis. Included studies featured various control groups, including placebo injection, hyaluronic acid injection, and no injection, as well as various concomitant treatments, including high tibial osteotomy, microfracture, platelet rich plasma injection and hyaluronic acid injection. Accordingly, clinical heterogeneity was assumed. Data was pooled from 12-24 month time points. Analyses on visual analog scale pain and Lysholm scores favoured MSC groups compared to control, while analyses on WOMAC total scores and MRI evaluations did not demonstrate a significant difference between groups.