Platelet-rich plasma (PRP), due to its high content of cytokines, bioactive proteins and platelet growth factors, may contribute to diminish the pain of arthritic knee. It was also recently recognized a regenerative cell potential improving the concentration of hyaluronic acid and stabilizing angiogenesis in arthritic knees

This study therefore seeks to assess the analgesic power of PRP in osteoarthritic knees intraarticularly infiltrated, and which patients would benefit most from treatment, eliminating false expectations in the rest.

This is the first clinical trial developed following the report of the Spanish Competent Authority on May 23, 2013, considering the PRP as a medicinal product for human use and establishing minimum guarantees required of the product and the process of manufacturing. It has been conducted from the perspective of both the trauma and the specialized treatment of chronic pain anesthesiologist, and manufacturing the PRP on the premises of a Regional Centre for Transfusions, all belonging to the Public Health System and therefore without commercial interests.

Inclusion Criteria:

• Arthritis in the knee rated I, II, or III (Kellgren-Lawrence Grading Scale)
• VAS greater than 5
• Between 40and 80 years of age

Exclusion Criteria:

• Level IV arthritis of the knee
• Either surgery, corticoid infiltration, or viscosupplementation in the knee in the previous three months
• Frontal deformity greater than 10 degrees
• Ipsilateral pathology of the knee or ankle
• Range of motion or flexibility of the knee less than 90 degrees
• Deficit of knee extension greater than 15 degrees
• Anticoagulation treatment, antiplatelet treatment
• Hepatopathy
• Hematological neoplastic pathology
• Active infection
• Fibromyalgia
• Chronic fatigue syndrome