Editorial Commentary: Platelet-Rich Plasma Injections Produced a Significant Improvement in Most Patients With Rotator Cuff Tendinopathy.

Platelet-rich plasma (PRP) is an autologous blood product containing a high concentration of platelets, growth factors, and cytokines, which basic science studies have shown may improve tendinopathy. However, there is controversy over its clinical efficacy with randomized controlled trials and subsequent meta-analysis finding mixed results when treating shoulder rotator cuff tendinopathy. The effect of leukocyte concentration on PRP has been shown to be paramount, with different concentrations being favored for different pathologies. In those with tendinopathy, it is unclear whether leukocyte-rich or leukocyte-poor PRP is superior. Recent research shows that PRP injections produced a significant improvement in most patients with rotator cuff tendinopathy. However, improvement in symptoms and functional outcomes is worse in patients who have a partial-thickness rotator cuff tear compared with isolated tendinopathy without a partial tear. PRP may be more advantageous than corticosteroids. Both function as anti-inflammatories, but PRP may be potentially anabolic, whereas as corticosteroids have a catabolic effect on tendons, which may reduce repairability if patients proceed with surgery. Additionally, there are higher infection rates if patients ultimately go on to surgery within 3 months after corticosteroid injections. Ultimately, we must refine the indications for best use for PRP shoulder injections and determine the 5 R's: right patient, right drug, right dose, right route, and right time. Finally, we must remember that patients can first try conservative management, including physical therapy.