The management of chondral disease is challenging. New studies have focused on modern therapeutic methods that stimulate cartilage healing process and improve the damage, including the use of platelet-rich plasma (PRP). PRP is prepared from autologous blood by centrifugation to obtain a highly concentrated sample of platelets. Due to the mixed results from controlled studies, the clinical efficacy of PRP in the treatment of knee OA is unclear with shortcomings in the current literature.

A comparison of the outcomes of randomized controlled trials (RCTs) included in the 3 most recent and high-quality meta-analyses to classify the different studies in 2 groups (bad responders group (BRG) and very good responders group (VGRG)). The minimal clinically important improvement (MCII) was defined to help determining whether an observed difference is clinically important. We used MCII values to classify the different studies in 2 groups depending on the outcomes: BRG<MCII and VGRG>2xMCII.

From the 19 RCTs analyzed, 7 trials were included in the VGRG and 4 in the BRG. In VGRG, 1 or 2 injections were performed in 4/7 trials, time between injections was 2 to 3 weeks in 4/5 studies with many injections, volume injected varied from 2.5 to 8mL, and single spinning technique was used in 5/7 studies. PRP classification was Mishra 4B and PAWP2Bβ in 5/7 studies. The use of PRP with leukocytes is only found in the BRG.

Our study helped identify features of PRP recommended for knee OA treatment, such as the use of a single spinning technique, a platelet concentration lower than 5 times the baseline (from 3 to 4), and avoiding leukocytes and erythrocytes. We recommend leveraging this information about PRP for future studies.