Comparison of Conventional Dose Versus Superdose Platelet-Rich Plasma for Knee Osteoarthritis: A Prospective, Triple-Blind, Randomized Clinical Trial

Background: Confusion persists regarding the ideal dosage of platelet-rich plasma (PRP) injection for knee osteoarthritis (OA). Purpose/Hypothesis: The purpose of the study was to compare the efficacy of 2 different single-injection PRP dosages in patients with early knee OA-a conventional 4 mL dose and a superdose of 8 mL. It was hypothesized that 8 mL of PRP would be superior to 4 mL of PRP in this patient population. Study Design: Randomized clinical trial; Level of evidence, 1. Methods: Patients with early knee OA (Kellgren-Lawrence grades 1 and 2) who met the inclusion criteria were randomly divided into 2 groups: Group A (n = 50 knees) received a 4-mL PRP injection, and group B (n = 49 knees) received an 8-mL PRP injection, both prepared using the same procedure. Patients were evaluated at the baseline, 6 weeks, 3 months, and 6 months using the Western Ontario and McMaster Universities Arthritis Index (WOMAC), the WOMAC-Pain subscale, the visual analog scale for pain, the Knee injury and Osteoarthritis Outcome Score, and patient satisfaction, and results were compared between the groups. Results: The baseline characteristics of the 2 groups were comparable (group A: mean age, 51.96 +/- 6.93 years; group B: mean age, 49.12 +/- 9.8 3 years). Leucocyte-depleted PRP with 3.5 times concentration (final product platelet concentration, 706.74 x 103-mu L) was injected. The mean absolute platelet count injected was 2.82 +/- 0.0012 billion in group A and 5.65 +/- 0.0022 billion in group B. All patient-reported outcome scores improved significantly in both groups from the baseline to the final follow-up (P < .001), with overall trends and results significantly better in group B than in group A (P < .001). Patient satisfaction at the 6-month follow-up was also better in group B (96%) compared with group A (68%). Short (2 to 7 days) self-limiting complications, such as pain and stiffness, occurred more often in group B (P < .001). Conclusion: Patients with early knee OA had significantly better improvement in pain and function when treated with an 8-mL injection of PRP compared with a 4-mL injection of PRP. The larger dose of PRP had approximately twice the number of platelets.