Comparative effectiveness of platelet-rich plasma injections for treating knee joint cartilage degenerative pathology: a systematic review and meta-analysis.

OBJECTIVE: To explore the effectiveness of platelet-rich plasma (PRP) in treating cartilage degenerative pathology in knee joints.

DATA SOURCES: Electronic databases, including PubMed and Scopus, were searched from the earliest record to September 2013.

STUDY SELECTION: We included single-arm prospective studies, quasi-experimental studies, and randomized controlled trials that used PRP to treat knee chondral degenerative lesions. Eight single-arm studies, 3 quasi-experimental studies, and 5 randomized controlled trials were identified, comprising 1543 participants.

DATA EXTRACTION: We determined effect sizes for the selected studies by extracting changes in functional scales after the interventions and compared the PRP group pooled values with the pretreatment baseline and the groups receiving placebo or hyaluronic acid (HA) injections.

DATA SYNTHESIS: PRP injections in patients with knee degenerative pathology showed continual efficacy for 12 months compared with their pretreatment condition. The effectiveness of PRP was likely better and more prolonged than that of HA. Injection doses ≤2, the use of a single-spinning approach, and lack of additional activators led to an uncertainty in the treatment effects. Patients with lower degrees of cartilage degeneration achieved superior outcomes as opposed to those affected by advanced osteoarthritis.

CONCLUSIONS: PRP application improves function from basal evaluations in patients with knee joint cartilage degenerative pathology and tends to be more effective than HA administration. Discrepancy in the degenerative severity modifies the treatment responses, leading to participants with lower degrees of degeneration benefiting more from PRP injections.