Six studies (4 randomized controlled trials and 2 prospective cohort studies) were included in this quantitative systematic review which investigated the efficacy of platelet-rich plasma (PRP) injections versus hyaluronic acid (HA) or placebo injections. Pooling was performed on outcomes reported at a 24-week follow-up. The pooled results indicated that functional outcomes were significantly better among the PRP treatment cohorts compared to control groups. However, there was no statistically significant difference between groups with respect to pain and treatment satisfaction outcomes.