Presence or absence of leukocytes makes no difference in effectiveness of PRP injection in persons with knee osteoarthritis

Reference

Di Martino A, Boffa A, Andriolo L, et al. Leukocyte-rich versus leukocyte-poor platelet-rich plasma for the treatment of knee osteoarthritis: a double-blind randomized trial. Am J Sports Med 2022;50(3):609-617.

Synopsis

Although meta-analyses on the effectiveness of platelet-rich plasma (PRP) injections are discordant and the American College of Rheumatology makes a strong recommendation against its use, these authors explored the possibility that the presence of leukocytes makes these injections less effective. They recruited 192 adults with mild to moderate knee osteoarthritis (based on x-ray results), had at least 4 months of pain or swelling, and had failed to improve after at least 2 months of nonoperative treatment. The authors randomized the patients to receive 3 weekly injections of leukocyte-rich plasma or 3 weekly injections of leukocyte-poor plasma. There was no sham or placebo group. Researchers uninvolved in the injections and unaware of treatment allocation evaluated the participants at baseline and then at 2, 6, and 12 months. After 12 months, the participants in each group improved at each interval and there was no significant difference in the degree of improvement from baseline, regardless of treatment. The authors report that adverse events were generally mild, infrequent, and occurred with similar frequency in each group. The study was designed to be able to detect clinically meaningful differences. The findings are comparable with those reported in a recent network meta-analysis of 23 studies with 2260 participants. Of course, all this is specious if PRP injections are no more effective than placebo.