Joost Peerbooms

53 PRP in upper limb conditions INTRODUCTION The literature contains many studies documenting the safe and efficacious use of platelet-rich plasma (PRP) for upper limb injuries. In many cases, the terms autogenous platelet concentrate, platelet gel and fibrin glue are used as synonyms for PRP. Many of these studies claim to have excellent outcomes, although they are limited to case series; consequently, it is difficult to draw conclusions from these case reports, which may or may not have controls, have small sample sizes, and do not define a standardized preparation of PRP. This makes it hard to interpret any of the results obtained. 1 Standardized dosing and composition of PRP is necessary in order to compare the data from different studies. Unfortunately, most of these human clinical studies lack statistical significance because of small sample sizes and a paucity of randomized controlled trials. Recently the first two randomized controlled trials using PRP were published. Both studies are of Dutch origin. One deals with chronic achilles tendinopathy and the other one deals with chronic lateral epicondylitis. 2,3 Because of the outcome of the former study, the New York Times reported that ‘Popular Blood Therapy Might Not Work’. This in contrast to an earlier publication in the New York Times of “’New Blood Therapy Saves Superbowl’. 4 The latter study published a positive effect of PRP treating chronic lateral epicondylitis. Efforts are currently underway aiming to design clinical studies that will help further delineate the effects of PRP. PLATELET-RICH PLASMA In 1998, discussion started about the use of PRP. 5 PRP is a volume of autologous blood plasma with a platelet concentration above the reference value. The reference value for platelet count in blood is between 150,000/µL and 440,000/µL. PRP commercial application systems have shown that the platelet concentration in PRP can increase between 160% and 740%. To create a possible therapeutic effect, a 400% to 500% increase of platelets is needed to achieve a PRP platelet volume reaching 1,000,000 / μL in a volume of 5 mL. 6 PRP can accelerate healing by releasing a variety of growth factors and cytokines from activated platelets. The basic cytokines released from platelets include: transforming growth factor (TGF), platelet-derived growth factor (PDGF), insulin-like growth factor-I and II (IGF-I, IGF-II) and vascular endothelial growth factor (VEGF). These cytokines play an important role in cell proliferation, chemotaxis, cell differentiation and angiogenesis (Table 1). 7 All these cytokines in the PRP are normally present in biological ratios. 4