To assess if there are any differences among platelet-rich plasma, hyaluronic acid, and corticosteroid knee intra-articular injection regarding function and pain.

Inclusion Criteria:

• Patient aged 35-65 years old
• Patient with knee pain that had been continuing for at least 12 months with no relief using anti-inflammatory medications and that deteriorated with weight-bearing
• Knee osteoarthritis that classified as mild-moderate or moderate-severe (Kellgren-Lawrence Grade 2, 3, or 4)

Exclusion Criteria:

• Age > 65 years
• The recent history of knee trauma
• Autoimmune rheumatic diseases
• Accompanying severe hip OA
• Thrombocytopenia or other blood diseases
• Immunosuppressive or anticoagulant treatment
• The invasive procedure applied to the knee
• Intra-articular steroid injection to the knee within the previous 12 months
• Previous joint infection
• Uncontrolled systemic diseases such as diabetes or hypertension, and cancer
• Excessive varus/valgus knee deformity