What is the diagnostic differential for osteoarthritis of the knee? Common Symptoms of Osteoarthritis of the Knee? Knee osteoarthritis, also known as knee joint proliferative arthritis, degenerative arthritis and osteoarthropathy, is a chronic bone and joint disorder caused by degeneration of knee joint cartilage and osteomalacia, which is clinically manifested as knee joint pain and different degrees of dysfunction, and some of them have joint swelling and effusion, which seriously affects the quality of life of patients, and the X-ray manifests narrowing of the joint space, bone capillaries on the edges of the joints Formation of subchondral osteosclerosis and cystic changes. It occurs mostly in middle-aged and old people, but also in young people. It can be unilateral or bilateral, and is more common in women than in men. Etiology The cause of primary osteoarthritis of the knee is not yet fully understood, and is generally believed to be related to the following factors: age: from middle age to old age, with age, due to years of cumulative strain on the joints, often occurring degenerative changes in articular cartilage. Gender: Both men and women can be affected, but it is more common in women, especially those before and after menopause, suggesting that the disease may be related to hormonal changes in the body. Weight factor: OA is related to body mass index: for every 10 pounds of body weight increase, the incidence of OA increases by nearly 40%; weight loss can reduce the incidence of OA. increased BMI (height and weight index) has a relationship with WHR (waist-to-hip ratio), from the age of 18 years old when the BMI can be predicted later WHR. studies have shown that a reduction of 5 kilograms of body weight, joint pain can be reduced by 20%, reduce body weight plus suitable after exercise and Medication is as important, if not better. Joint damage and overuse: Any cause of abnormal joint shape can alter the transmission of joint loads and cause osteoarthritis by increasing localized loads and wear on articular cartilage surfaces. Bone density: When the subchondral bone trabeculae become thin and hard, their ability to withstand pressure decreases. Therefore, osteoporosis has a higher incidence of osteoarthritis of the knee joint. Clinical manifestations 1. Pain: Irritation of nerve endings emanating from the nerves around the joints is the main cause of osteoarthritis pain. Pain also comes from the synovial membrane in the joint capsule and its surrounding areas, muscle spasm around the joint, inflammation of the ligaments around the joint or the subchondral bone, etc. The pain level ranges from mild to severe. According to the degree of pain from mild to severe can be divided into five degrees: 1 degree: no pain; 2 degrees: mild; 3 degrees: moderate; 4 degrees: severe; 5 degrees: severe. Most patients with knee pain belongs to the mild and moderate, mostly dull pain, accompanied by a feeling of heaviness, soreness, bruising, discomfort in activities. 2.Swelling: some patients have swollen joints and recurrent episodes. 3.Deformity:the knee joint may have inversion or eversion deformity, and the bone edge of the joint is enlarged. Some patients can not completely straighten the knee joint, and in severe cases, the knee joint is flexion contracture deformity. 4, dysfunction, abnormal motor rhythm: playing soft legs, popping sound, strangulation. Diminished motor ability: joint stiffness, instability, limited flexion and extension, walking ability. Laboratory tests The general condition is mostly normal. Synovial fluid analysis is also normal, clear, yellowish, and viscous, with a white blood cell count that is often less than 1,000, and occasionally can reach several thousand, mainly mononuclear cells, with occasional firm mucin clots, and sometimes erythrocytes, cartilage, and fibrous debris. Diagnosis Diagnostic criteria for osteoarthritis of the knee: 1, recurrent knee pain in the past month; 2, X-ray (standing or weight-bearing position) shows narrowing of the joint space, subchondral osteosclerosis, and/or cystic changes, and formation of bony encumbrances at the joint margins. 3, Joint fluid (at least 2 times) was cool and viscous with leukocytes <2000/ml; 4, Middle-aged or elderly patients (≥40 years old); 5, Morning stiffness <15 minutes; 6, Bone rubbing sensation during activity. 7, Bone end hypertrophy of knee joint, localized swelling of different degrees, reduced or restricted range of flexion and extension activities. 1+2, 1+3+5+6, 1+4+5+6 can confirm the diagnosis of X-ray examination of the basic features 1, joint space narrowing: adult knee joint gap is 4mm, less than 3mm is the joint space narrowing, 60 years old and above the knee joint gap is 3mm, less than 2mm is the joint space narrowing. 2.Sclerosis of subchondral bone plate: the subchondral bone plate is dense and hardened, and cystic changes can be seen in the weight-bearing subchondral bone. 3.Bone redundancy formation. Differential diagnosis Lateral collateral ligament injury of knee joint: there is fixed compression pain at the site of ligament injury, often at the upper and lower attachment points of the ligament or in the middle of the ligament, the knee joint is in a semi-flexed position, and the activity of the joint is limited, and the lateral compression test is positive. Knee meniscus injury: history of trauma, post-injury joint pain, swelling, popping and strangulation phenomenon, knee internal and external interstitial pressure and pain, quadriceps atrophy in the chronic stage, especially obvious with the medial quadriceps muscle, and positive Mai's test and grinding test.