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

Abstract

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 × 10³-μL) 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.

Registration: CTRI/2020/02/023403 (Clinical Trials Registry-India identifier).

Keywords: knee; osteoarthritis; platelet-rich plasma; superdose platelet-rich plasma.

Figure 1.

A CONSORT flowchart of participant inclusion in the study. CONSORT, Consolidated Standards of Reporting Trials.

Figure 2.

The area under the ROC curve depicts the diagnostic value of the calculated MCID of 25% in the WOMAC-Pain score. MCID, minimum clinically important difference; ROC curve, receiver operating characteristic curve; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.

Figure 3.

Trends in the WOMAC-Pain, WOMAC total, VAS pain, and KOOS scores, respectively, over sequential follow-up. KOOS, Knee injury and Osteoarthritis Outcome Score; VAS, visual analog scale; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index. *Significant differences between groups for that time point (P < .05, Wilcoxon signed-rank test).