Summary

This study evaluates the efficacy of PRP therapy for knee osteoarthritis using data from Japan's National Regenerative Medicine Database, finding that PRP is less effective in older patients, males, and those with severe osteoarthritis or poor alignment, with Kellgren-Lawrence classification being the most significant factor.

Abstract

Background

PRP therapy for knee OA has become increasingly popular in recent years, but is not yet recommended in treatment guidelines in Japan due to insufficient evidence. The indications and limitations of this treatment need to be investigated, and this was the aim of the present study.

Methods.
We registered cases in the National Regenerative Medicine Database (NRMD) since 2020 and extracted cases with a pre-treatment VAS of 30 or more and a 6-month post-treatment VAS from the NRMD. The group with a VAS improvement of 15 or more was defined as the responder group (R group) and those with a VAS of 15 or less as the non-responder group (NR group). Statistical analysis was performed using SPSSVer28 with chi-squared and t-tests. The significance level was set at 0.05%.

Results

Of the 2815 knees enrolled in the NRMD, 889 knees were selected. Kellgren-Lawrence classification (KL) was confirmed in 727 knees (KL1/2/3/4=33/142/303/249), 354 knees in the R group and 535 knees in the NR group with a responder rate of 60.2%. The significant differences between the R and N groups were age 65.7/68.1 (p=0.04). Sex (male/female) was 154/381 in the R group and 127/227 in the NR group (p=0.02), with women being more effective. KL classification (1/2/3/4) was 21/91/193/122 in R and 12/51/110/127 in NR (p=0.02), %MA was 31.6 in R and 25.9 in N (p=0.01), severe OA and poor alignment were less effective. Logistic analysis with age, BMI and KL classification extracted the KL classification. The odds ratio was 0.78, 95% CI 0.63-0.97, p-value 0.028.

Conclusion

There have been several reports of poor efficacy with increasing severity of OA and the results of this study are consistent with previous studies. PRP for knee OA was less effective in older patients, males, KL4 and poor alignment. The most influential determinant of the effect for knee OA was the KL classification. In addition to these factors, the number of blood cells in the PRP, the location of the OA, and the presence or absence of PFOA were also studied but did not affect the effectiveness of PRP. It is necessary to continue studying effective and ineffective cases of PRP to determine the limitations and indications for treatment.