Comparison of Effectiveness Between PL and PRP on Knee Osteoarthritis: a Prospective,Randomized,Placebo-controlled Trial

Inclusion Criteria: * 50 to 80 years old * Study Subjects must be willing to sign Informed Consent to participate in the study * In the past month, at least seven consecutive days in the squat, standing, walking or going up and down the stairs, the most serious degree of visual analogy of the knee pain (Visual Analogue Scale) is greater than or equal to 40 (the most pain is 100, not painful is 0) * Morning joint stiffness is less than 30 minutes * X-ray：Grade 1-3 radiographic OA as defined by the K-L classification Exclusion Criteria: * Knee instability * The knee joint is obviously deformed (\> 5 degree valgus or varus deviation on X-ray) * Clinical diagnosed as Pes tendinitis, Chondromalacia * Taking NSAIDs or steroids (including oral and injection) within one week * Using anticoagulant drugs for a long time * Platelet count is less than 150,000 / UL, or coagulation disorders, prothrombin time (PT value) is less than 11 seconds or greater than 16 seconds * Leukemia, sepsis, platelet dysfunction or other blood related diseases * tumors, infections or the trauma before the same site * Pregnancy