Another study fails to find PRP injections effective for adults with degenerative joint disease of the knee

Reference

Lewis E, Merghani K, Robertson I, et al. The effectiveness of leucocyte-poor platelet-rich plasma injections on symptomatic early osteoarthritis of the knee: the PEAK randomized controlled trial. Bone Joint J 2022;104-B(6):663-671.

Synopsis

These authors point out that platelet-rich plasma (PRP) injections are controversial because the studies, with largely negative results, have been at high risk of bias. However, the biases in those studies generally stack the deck in favor in PRP! Anyway, these authors felt it necessary to improve on the previous work. They recruited adults with at least 4 months of knee pain (with or without swelling) who had mild degeneration on their x-rays (if plain x-rays found no signs of degeneration, they used magnetic resonance imaging to confirm the diagnosis). The participants were randomized to receive 3 weekly saline injections (n = 28), a single PRP injection followed by 2 weekly saline injections (n = 47), or 3 weekly PRP injections (n = 27). The researchers collected blood at each visit (to be used either as the PRP source or as a procedural disguise) and blindfolded each patient to prevent unmasking of the intervention. The authors don't describe if the injections were guided by ultrasound or if they used a local anesthetic. The clinician performing the injections was unmasked but had no other involvement in the study procedures. The researchers evaluated the participants at 6 weeks, 12 weeks, 6 months, and 12 months after enrollment. Using intention-to-treat analysis applied to several standardized measures of pain, function, and quality of life, at no point in the study were PRP injections, singly or serially, superior to saline injections. Other than a higher risk of transient localized swelling in the participants who received PRP injections, the authors report no differences in redness or bruising and that no participant experienced infections. Please note that the authors used leukocyte-poor PRP injections, but recent studies have found no meaningful differences between leukocyte-poor and leukocyte-rich PRP injections in persons with knee osteoarthritis.