Osteoarthritis is the most common type of arthritis. The prevalence of osteoarthritis of the knee has significantly elevated in the elderly population and youth due to age and sport activities respectively. Our aims to treat the knee osteoarthritis are including; reduce knee pain and improve its function; return patients to normal daily activities and reduce health care costs.

The current treatments which are already being used for osteoarthritis of the knee patients include:

1. Symptomatic therapy: conservative therapies, physiotherapy, analgesics and non-steroidal anti-inflammatory drugs.
2. Intra-articular injections of corticosteroids and hyaluronic acid.
3. Current Surgical Therapy: knee arthroplasty, osteotomy, arthrodesis and debridement.

As the low mitotic activity and lack of blood supply cause little ability for the articular cartilage to repair itself, so injection of platelet-rich plasma (PRP) has recently received much more attention due to its capacity to do self-healing in treatment of osteoarthritis of the knee.

PRP consists of several concentrated growth factors in platelets of autologous blood that are applied to the different parts of medicine such as reconstruction of damaged tissue. Although platelets are well-known to involve in the blood clots formation, but current studies have shown that they secrete many bio-proteins which attract macrophages, mesenchymal stem cells and osteoblasts to remove necrotic tissue in addition to participate in healing procedure.

This study is a prospective, randomized, controlled trial to assess The positive effects of platelet-rich plasma injection in 244 patients with osteoarthritis of the knee

In this study all eligible patients (Based on the inclusion and exclusion criteria) were randomly allocated into two study groups by a Stratified Permuted Block randomization method: group A received platelet rich plasma, group B (control group) received only placebo.

All of the patients underwent a standard long protocol for knee osteoarthritis. All patients with grade II,III and IV of radiographic knee OA are selected. On average, in each instance, the amount of platelets in the peripheral blood is 4 to 6 times the baseline level.

Group A: 1-3 cc injection of placebo Group B: 1-3 cc injection of PRP All patients received monthly injection for 3 times.

Inclusion Criteria:

1. Age 18 to 65 years
2. Body mass index (BMI) ≤33 kg/m2
3. Grade 2And above imaging of osteoarthritis
4. History of knee pain or swelling should have at least 4 months

Exclusion Criteria:

1. treated with steroids and Anti-coagulant or anti-platelet aggregation
2. history of infectious, systemic diseases, Immune deficiency and coagulation disorders
3. Patients with Hb ≤11, Plt ≤ 150000
4. Varus > 10 , valgus > 10