The clinical diagnosis of knee osteoarthritis includes symptoms, signs, laboratory tests and imaging examinations. I. Symptoms and signs 1. Joint pain and pressure pain: Initially, mild or moderate intermittent occult pain that improves with rest and worsens with activity, often related to weather changes. In the late stage, there may be persistent pain or nocturnal pain. There is localized pressure pain in the joints, which is especially obvious when accompanied by joint swelling. 2. Joint stiffness: stiffness and tightness of the joints when waking up in the morning, also known as morning stiffness, can be relieved after activity. Joint stiffness is aggravated when air pressure decreases or air humidity increases, and the duration is generally short, often a few minutes to ten minutes, rarely more than 30 minutes. 3. Enlarged joints: The joints of the hands are enlarged and deformed, and Heberden’s nodes and Bouchard’s nodes may appear. Some of the knee joints may also be enlarged due to the formation of osteoid or joint effusion. 4. Bone rubbing sound (sensation): Due to the destruction of articular cartilage and uneven joint surface, bone rubbing sound (sensation) appears when the joint moves, mostly in the knee joint. 5.Joint weakness and activity disorders: joint pain, decreased mobility, muscle atrophy, soft tissue contracture can cause joint weakness, soft legs or joint locking when walking, inability to fully straighten or activity disorders. Second, laboratory tests Blood routine, protein electrophoresis, immune complexes and serum complement and other indicators are generally in the normal range. Patients with synovitis may have mildly elevated C-reactive protein (CRP) and hematocrit (ESR). X-ray examination Asymmetric joint space narrowing, subchondral bone sclerosis and/or cystic changes, joint edge hyperplasia and bone redundancy or joint effusion of different degrees, some joints can be seen free body or joint deformation.