Design: Systematic review and meta-analysis of randomised controlled trials
Population: 12 trials, 1,200 patients with knee osteoarthritis
Primary outcome: Imaging-based structural outcomes
Effect: Patellofemoral cartilage SMD 0.94; no difference in medial tibial cartilage, defects or synovitis

This meta-analysis pooled 12 randomised trials and 1,200 patients that measured structural outcomes on imaging after platelet-rich plasma injection for knee osteoarthritis.

Platelet-rich plasma was associated with greater patellofemoral cartilage thickness or volume (SMD 0.94, 95% CI 0.53 to 1.34) and less bone marrow oedema (SMD −0.40, −0.71 to −0.09). It showed no difference in medial tibial cartilage, cartilage defect progression, osteophytes, subchondral cysts or synovitis.

The authors conclude the evidence does not support platelet-rich plasma as a structure-modifying treatment, and the isolated positive findings, in a few of many outcomes, should be read with caution. Platelet-rich plasma is widely marketed, including in India, and patients often ask about it as a way to regrow cartilage. That claim is not supported.

Tell patients that platelet-rich plasma has not been shown to regrow or protect knee cartilage.
Do not offer platelet-rich plasma as a disease-modifying treatment for knee osteoarthritis.
Prioritise exercise, weight loss and established analgesia for knee osteoarthritis.
Treat isolated positive imaging results in these trials as hypothesis-generating.

Why it matters

A heavily marketed injection is often sold on a structural claim that the trial evidence does not support.

The statistics, in plain English

When many structural outcomes are tested, one or two will reach significance by chance. Two positive results among about eight measures, without consistency across cartilage regions, is the pattern expected from chance or bias rather than a true structural effect.