Evidence from 6 studies (4 RCTs and 2 Prospective Cohort Studies) was analysed to determine differences in treatment outcomes for knee osteoarthritis between Platelet-Rich Plasma (PRP) and Hyaluronic Acid (HA) or placebo. A total of 577 patients were included in the analysis, 264 (45.8%) allocated to PRP and 313 (54.2%) allocated to a control (HA or placebo). The evidence presented in this study demonstrated that the administration of PRP resulted in superior Western Ontario and McMaster Universities Arthritis Index (WOMAC) and International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC) scores, when compared against the application of HA or a placebo. PRP was associated with significantly more adverse events. VAS pain and satisfaction was comparable between treatments.