2016 ACR Revised Criteria for Early Diagnosis of Knee Osteoarthritis

Osteoarthritis (OA) is cartilage failure resulting in joint pain and loss of joint functions. Knee OA is the OA of knee that mechanical forces have major effect on initiation and progression of it. Knee OA is the most common disease of knee especially in the middle to old ages. The most common findings in the history and physical examination of the patients with knee OA are mechanical knee pain, gelling knee pain, crepitus on knee motion, bony tenderness and bony enlargement in the joint line. During the flare up of Osteoarthritis, knee can show swelling due to joint effusion called “Hydrarthrosis” that is a mechanical type of synovial fluid. It is usually a cold effusion and sometimes it is accompanied by warmth and mild synovitis or synovial thickening, but moderate to significant knee synovitis and hot or red knee cannot be seen during its OA flare up. Factors that place the people at higher risk for knee OA are: middle to old ages, obesity, frequent knee bending activity, climbing the stairs frequently, squatting or deep knee bending for prolonged time and lifting or moving heavy objects frequently. There is not any significant positive finding in biochemistry tests of the patients with knee OA. Plain radiography has low sensitivity regarding knee OA during the early phase of the disease but the MRI of knee is the most sensitive imaging during this early phase. Among the X-Ray findings, osteophyte has the most specificity for OA and the presence of cartilage defects and Bone Marrow Edema (BME) concomitantly are compatible MRI findings for OA. The diagnosis of knee OA can be usually made by clinical/imaging judgment of an expert physician. There are three ACR classification criteria for knee OA that are useful for research purposes but they are not valuable for early diagnosis of knee OA. By this letter, the author wants to deliver a new criteria called “2016 ACR revised criteria for early diagnosis of knee OA”.