Two, four injections of platelet-rich plasma improve clinical outcomes in knee osteoarthritis

Treatment with two or four intra-articular injections of platelet-rich plasma (PRP) confers stable clinical improvements in patients with knee osteoarthritis (OA) but has no demonstrable impact on the levels of synovial cytokine and growth factors, a recent study has found.

Researchers enrolled 94 knee OA patients who received PRP injections at 6-week intervals, of whom 51 received two injections (group A) while 43 were given four injections (group B). Synovial fluid aspiration was performed before and after each injection for the measurement of relevant biomarkers. Clinical outcome parameters were assessed after 1 year.

Groups A and B showed similar patterns of clinical improvement starting at 6 weeks after injection. For instance, pain, as reflected in the visual analogue scale, showed significant improvement at 6 weeks. The same was true for patient-reported outcome measures, including scores in the Short Form-12 and Western Ontario and McMaster Universities Osteoarthritis Index tools.

Meanwhile, performance-based measures started showing significant improvements by week 12. These included the timed up-and-go and 5-time sit-to-stand tests. The 3-minute walk test, another index of performance, saw improvements by week 18.

Notably, all such clinical impacts were stable and persisted until 1 year after injection.

However, despite such clinical improvements, the researchers documented no significant change in synovial fluid markers, including inflammatory cytokines, anti-inflammatory cytokines, and growth factors.