Patellar tendinopathy, also known as jumper's knee，is clinically common characterised by anterior knee pain, activity-related pain、local tenderness over inferior pole of patella. The discomfort can result in decreasing athletic performance and be one of the most challenge for sports medicine doctor.~The patellar tendon suffer from repetitive microtrauma，result in reactive patellar tendinopathy. The overload tendon combining with risk factors of patellar tendinopathy will not recover timely and progress to chronic patellar tendinopathy. Hence, to reverse the progression is our aim.~According to previous studies, several nonsurgical treatment options have been proposed such as medication, eccentric exercise, corticosteroid injection, shockwave and platelet-rich plasma (PRP). Among all the options, the effect of PRP could last longer. However, the type, concentration, time and frequent of injection are still debated。Moreover, there is no study about the relationship between efficacy and the ratio and concentration of growth factor in the PRP.~The aim of this study is to understand (1) The effect of multiple injection of platlet-rich plasma in chronic patellar tendinopathy. (2) The effect of leukocyte-rich PRP in chronic patellar tendinopathy (3) Analyze the relation between efficacy of PRP and the growth factor in PRP.
According to previous studies, the effect of PRP to patellar tendinopathy could last longer. However, the type, concentration, time and frequent of injection are still debated。 This study is to understand the effect of multiple injection of platlet-rich plasma in chronic patellar tendinopathy and to analyze the relation between efficacy of PRP and the growth factor in PRP.