Joost Peerbooms

127 Discussion No studies were found focusing on the possible antimicrobial effect of PRP leading to reduction of infection rate after TKA. Especially in high-risk cases (obesity, smoking, diabetics) studying the reduction of the infection risk by using PRP seems to be valuable. So far, a consensus on using PRP as a routine treatment for wound healing after TKA has not been reached. Wound healing is a complex process, and many factors, including surgical techniques and approaches may contribute to the process. Other patient conditions, including diabetes, obesity and smoking, may also impact wound healing. Therefore, a robust study with a large number of patients would be necessary to show the place of PRP in enhancing wound healing and infection prevention in TKA. SECTION III: PRP SYSTEMS Blood Components In Chapter 2 we reviewed literature about the concentrations of blood components in commercially available PRP separation systems. The literature revealed a significant amount of heterogeneity between the PRP separation systems available on the market, especially involving concentrations of platelets, leukocytes and growth factors in PRP. In our review we found a wide variety of growth factors, not only between the different separation systems, but also when different studies compared the same separation systems. We also found a strong correlation between the concentration of vascular endothelial growth factor (VEGF) and the concentrations of platelets and leukocytes. This correlation is also supported by other studies. 29,34 The concentration of platelets in PRP is important because the mechanism of action of PRP is mainly based on growth factors. Growth factors released by the platelets, platelet-derived growth factor (PDGF), transforming growth factor ß1 (TGF-ß1), VEGF and epidermal growth factor (EGF) are the most important factors involved in tissue repair. 35 The concentration of these growth factors is generally considered a marker of the quality of the PRP preparation. 35,36 However, there is no consensus about the optimal concentration of growth factors. 35,36 Currently, physicians can choose from over 30 PRP processing systems. 37-39 A lack of a consensus on standardising PRP has contributed to the significant variation in PRP products. Although the ideal concentrations of blood components and growth factors for specific fields of application have yet to be determined, the field of application should play an important role in the choice for the most appropriate PRP separation system. Other factors such as the volume of whole blood needed, the final volume of PRP and the usability and reliability of the separation system should also be taken into consideration. 8