109 patients with degenerative knee cartilage were randomized to determine the efficacy of platelet-rich plasma (PRP) compared to viscosupplementation via hyaluronic acid (HA) as a treatment method. Patients were allocated to three injections of either solution, and were followed up for 12 months. Results revealed that there were no differences between groups in clinical outcome for the duration of the study. Interestingly, a sub-group analysis of patients with lower degenerative status (Kellgren-Lawrence grade 0-II) indicated a trend of improved outcome with PRP, but did not reach statistical significance.