Platelet-rich plasma therapy for knee osteoarthritis: Insights from real-world clinical data in Japan

Knee osteoarthritis (KOA) is highly prevalent, and platelet-rich plasma (PRP) therapy has emerged as a novel treatment option. Although PRP is promising, its effectiveness remains controversial. In Japan, PRP therapy is administered as a self-funded treatment in specialized clinics. The National Regenerative Medicine Database (NRMD) was established to support the evaluation of regenerative therapies. This study aimed to analyze patient characteristics and treatment outcomes of PRP therapy for KOA in our hospital registered in NRMD database and to identify factors that influence therapeutic effectiveness.

This retrospective observational study analyzed PRP treatment data for KOA in our hospital from January 2020 to May 2024 which was registered in the NRMD. Leukocyte-poor PRP (LP-PRP) was prepared using the MyCells kit, and patients received three injections at 3- to 5-week intervals. The eligibility criteria included chronic knee pain unresponsive to conservative treatment for KOA. Visual Analog Scale (VAS) for knee pain were collected at baseline and 3 and 6 months post-treatment. Statistical analyses included paired t-tests, logistic regression, and one-way analysis of variance (ANOVA).

A total of 2068 patients (2815 knees) were included. The average age was 65.2 years, and there were more female than male patients. PRP therapy significantly improved the VAS scores from 53.5 at baseline to 35.8 at 6 months (P < 0.05). Patients with Kellgren-Lawrence (KL) grade 4 showed less improvement than those with KL grades 2 and 3. Blood neutrophil levels positively correlated with pain severity. VAS improvement negatively correlated with age and body mass index (BMI). No major adverse events were reported during the study period.

PRP therapy for KOA, as observed in the clinical setting in Japan, is a safe treatment option with significant pain reduction, particularly in patients with less severe deformity of KOA. However, its effectiveness decreases in severe deformity cases. These real-world clinical data provide valuable insights for refining the patient selection criteria and advancing KOA treatment strategies.