Acute and overuse tendon disorders are frequently observed in the middle-aged active population. Tendon overuse injuries are currently designated as "tendinopathy". Histopathological studies have shown that chronic tendinopathy is frequently characterised by degenerative changes, such as decreased organisation of collagen, altered cell distribution and neovascularisation. In the recent years, scientific research and technology in the field of regenerative medicine has provided a new perspectives on managing chronic tendinopathy. An initiation of tissue healing can be attempted by local delivery of growth factors. Nowadays, platelet-rich plasma (PRP) is a commonly applied approach to achieve this. Platelet degranulation leads to a release of various growth factors and cytokines. There is a classification system to define the different forms of PRP. In the past decade, a number of studies have been published on the effects of PRP in different basic science studies. These studies suggest that PRP modulates some aspects of tendon metabolic activity. This is one of the reasons why PRP is increasingly used by many clinicians as treatment option for tendinopathy in daily clinical practice. There is, however, evidence from the literature that it does not lead to improved outcome on imaging findings and on patient-reported outcomes. This questions the role of PRP injections as regular treatment for tendinopathy. Moreover, it results in a broader discussion on the required effects that need to occur for tendon healing and symptom relieve.
Keywords: Collagen structure; Growth factors; Neovascularisation; PRP; Tendinopathy; Tendon regeneration.