What tests can diagnose osteoarthritis? What's the point of each?

X-ray examination X-ray examination is an image record of human tissues. The bone structure develops best on X-ray film, but cartilage and soft tissue can't be seen clearly on X-ray film. However, if the gap between articular bone and bone is narrowed, it usually means that cartilage is damaged. The diagnosis of osteoarthritis is usually based on the physical examination results of medical history. X-ray examination is very helpful for diagnosis. X-ray examination may be the only special examination that most patients need. Doctors usually combine X-rays, medical history and physical examination results to comprehensively evaluate joint lesions. The manifestations of osteoarthritis are often very obvious on X-ray films. Its basic X-ray features are three points: 1, and the joint space becomes narrower, and even the joint space disappears in severe cases. 2. The subchondral bone density increased. 3, the formation of osteophyte, the so-called "bone spur" often forms osteophyte at the joint edge (actually cartilage edge) or soft tissue stagnation point. Only two of the above three points can be diagnosed as osteoarthritis. The patient's symptoms may or may not be consistent with the results of X-ray examination, especially in the early stage of the disease. Often before symptoms appear, joint injuries can be found on X-ray films, and some patients have no symptoms even if X-ray films are very serious. People over 40 years old, 60%~70% will have osteoarthritis on X-rays, but only 1/3 of these people will have osteoarthritis symptoms. If other diseases are suspected or the diagnosis is unclear on the X-ray film, other tests are needed. Rheumatoid factor examination is often used to exclude rheumatoid arthritis. Chemical hyaluronic acid can also be used as a marker to judge osteoarthritis. Hyaluronic acid provides lubrication for healthy joints and will decompose in joints of patients with osteoarthritis. A simple blood test of this decomposed by-product can show the progress of the treatment. Blood tests will show an increase in the level of a factor called C- reactive protein, which is produced by the liver in response to inflammatory reaction and is an "alarm" for the progress of knee osteoarthritis. 3, joint synovial fluid examination Only in the case of unclear diagnosis or suspected infection, it is necessary to use a needle to absorb synovial fluid from the joint for laboratory analysis. Under normal circumstances, there is very little synovial fluid in the joint, which is difficult to extract. If it can be extracted, there may be problems. The presence of chondrocytes in synovial fluid is a sign of osteoarthritis. White blood cell count helps to rule out the possibility of infection. High uric acid content in synovial fluid is a sign of gout, and other factors suggest different joint diseases, including rheumatoid arthritis. Some scholars hope that the increase of some substances in synovial fluid can be used to predict the severity of osteoarthritis. The most interesting ones are glucosamine sulfate, keratin sulfate and connexin, but they have not yet entered clinical application. 4. MRI * * * vibration examination Some patients with early osteoarthritis can't see the typical changes of osteoarthritis in X-ray examination, and the cause of pain is unclear. Is it osteoarthritis that causes pain, or other problems such as meniscus tear or patella? Sometimes it is necessary to observe the knee joint more clearly through MRI. Magnetic resonance imaging can clearly show not only bone tissue, but also soft tissue diseases such as ligament, articular cartilage and meniscus.