Editorial Commentary: Platelet-Rich Plasma Outlasts Hyaluronic Acid for Knee Osteoarthritis, but the Product, Not the Acronym, Is the Prescription.

Abstract

Intra-articular platelet-rich plasma (PRP) is among the most frequently administered orthobiologic treatments for symptomatic knee osteoarthritis. PRP is not a single intervention. Preparations differ in platelet concentration, total platelet dose, leukocyte and erythrocyte content, injection volume, activation method, and injection interval, such that 2 products sharing the acronym may constitute fundamentally different biologic treatments. The randomized literature supports a small symptomatic advantage of PRP over hyaluronic acid in mild-to-moderate disease. That advantage appears to emerge at 12 months rather than early and is best framed as symptom modification rather than cartilage regeneration. Whether any particular formulation drives the effect is far less certain. Reported associations between platelet concentration, leukocyte enrichment, activation status, and outcome are biologically plausible, yet they are typically carried by small and heavily overlapping sets of trials in which these variables cannot be separated from one another. Platelet concentration is furthermore not equivalent to platelet dose, which is the product of concentration and injection volume. Until absolute dose, leukocyte composition, activation, and final volume are consistently reported, comparisons of high versus low concentration remain uninterpretable. In our practice, PRP and hyaluronic acid are increasingly combined for a theoretical synergistic impact because viscosupplementation and biologic signaling address distinct components of the osteoarthritic joint. Standardized product characterization, dose-defined randomized trials, responder-based outcomes, and improved patient selection are warranted. The acronym is not the prescription; the product is.