A new systematic review with meta-regression, published in Knee Surgery, Sports Traumatology, Arthroscopy, examines which patient and PRP characteristics may be associated with treatment outcomes in knee osteoarthritis.

The analysis includes 20 randomized controlled trials involving 3,292 patients (1,774 PRP vs. 1,518 placebo) and evaluates outcomes at 6 and 12 months. The meta-analysis showed improvements in pain and function with PRP compared with placebo at both time points.

At 6 months, younger patient age was associated with better clinical outcomes. Regarding product-related variables, although a higher platelet count increase, leukocyte-rich PRP (LR-PRP), and CaCl₂ activation showed associations with outcomes, the results from the studies analyzed do not allow the independent contribution of each factor to be determined with sufficient precision. At 12 months, none of the moderators analyzed explained the outcomes.

Therefore, the findings do not support a specific PRP formulation. Rather, they identify potential factors associated with short-term response and raise new hypotheses about how patient and product characteristics may interact.

What do we know about these factors, and which questions remain open?

Referencia: Delgado D, Andrade R, Gomes E, Lopes T, Azofra J, Espregueira-Mendes J, et al. Younger age and platelet-rich plasma characteristics influence short-term outcomes in knee osteoarthritis, but independent effects remain uncertain: a systematic review with meta-analysis and meta-regression of placebo-controlled randomised trials. Knee Surg Sports Traumatol Arthrosc. 2026; 1–16. https://doi.org/10.1002/ksa.70567