Comparative Analysis of the Effectiveness of Intra- Articular Injection of Platelet-Rich Plasma versus Hyaluronic Acid for Knee Osteoarthritis: Results of an Open-Label Trial

Background: Platelet-rich plasma (PRP), an autologous source of growth factors, and hyaluronic acid (HA) are among the minimally invasive treatments for knee osteoarthritis (OA). This trial was designed to compare the effectiveness of intra-articular injection of PRP with HA (as one of the standard treatments) on mild to moderate knee OA. Methods: In this phase I open-label clinical trial, 10 patients underwent intra-articular PRP injection and 10 others received HA injection. At baseline (pre-injection) visit and 1, 3, 6, and 12 months post-injection, clinical assessments were performed using visual analogue scale (VAS) and Knee injury and Osteoarthritis Outcome Score (KOOS) questionnaire. Physical examinations of the knee, including crepitation and range of motion (ROM) were performed at each visit. The follow-up responses were compared with the baseline visit. Results: The PRP treatment was ascertained to be safe and caused no adverse effects. Significant improvements in the majority of KOOS subscales and VAS were found throughout the entire 12-month follow-up, following the PRP injections. HA injection, however, caused only one month significant improvement in the majority of patient-reported outcomes. In the majority of visits, the extent of improvements in the scores of KOOS subscales, as well as the extent of reduction in VAS were significantly greater in PRP recipients, compared to HA recipients. The ROM in both groups slightly increased after interventions. The frequency of coarse crepitation, which was detected in 100% of the patients in both groups at the baseline visit, decreased significantly to fine crepitation at the first follow-up visit in 80% and 40% of the PRP and HA recipients, respectively. Conclusion: Intra-articular injection of PRP or HA alleviates symptoms and pain and improves functionality and physical examinations in patients with knee OA. However, PRP therapy produces greater and longer-lasting improvements in most of the outcome parameters compared to HA.