Osteoarthritis is a degenerative disease caused by ageing, obesity, strain, trauma, congenital abnormalities of joints, joint deformities and many other factors, such as degenerative damage to joint cartilage, reactive hyperplasia of joint edges and subchondral bone, also known as osteoarthrosis, degenerative arthritis, age-related arthritis, hypertrophic arthritis, etc. Clinical manifestations include slowly developing joint pain, pressure pain, stiffness, joint swelling, limitation of motion and joint deformity. The etiology of osteoarthritis is divided into two categories: primary and secondary, depending on the presence or absence of local and systemic pathogenic factors. Secondary osteoarthritis (1) Mechanical or anatomical abnormalities Abnormal hip development, slipped femoral epiphysis, abnormal femoral neck, multiple epiphyseal dysplasia, old fractures, post-hemiscectomy, post-arthroplasty, acute and chronic injuries. (2) Inflammatory joint disorders septic arthritis, osteomyelitis, tuberculous arthritis, rheumatoid arthritis, seronegative spondyloarthropathy, Behçet’s syndrome, Paget’s disease. (3) Metabolic abnormalities Gout, Gaucher’s disease, diabetes mellitus, progressive hepatomegaly, chondrodysplasia, hydroxyapatite crystals. (4) Endocrine abnormalities Acromegaly, sex hormone abnormalities, hyperparathyroidism, hypothyroidism with mucinous edema, hyperadrenocorticism. (5) Neurological defects Peripheral neuritis, spinal cord cavitation, Charcot arthropathy. 2.Primary osteoarthritis The etiology of primary osteoarthritis is unclear and may be related to factors such as advanced age, female, obesity, and occupational overuse. Clinical manifestations The main symptom is joint pain, which often occurs in the morning, but the pain is relieved after activity, but the pain can be aggravated if there is too much activity. Another symptom is joint stiffness, which often occurs in the morning when waking up or during the day after the joint has been in a certain position for a long time. Examination of the affected joints shows swelling, pressure and pain, and a feeling of friction or “clicking” sound when moving. Laboratory examination 1. There is no abnormal change in the hematocrit and blood picture. The joint fluid is often clear, slightly yellow and viscous, and the white blood cell count is often within 1.0×109/L, mainly mononuclear cells. The mucin clot is solid. 2.Other auxiliary examinations X-ray plain film has no obvious abnormality in the early stage, and the joint space is narrowed gradually after about several years, which indicates that the articular cartilage has begun to thin. At the beginning, the joint space is normal when not bearing weight, but after bearing weight, it becomes narrow. CT and MRI examinations can detect abnormal changes of articular cartilage and subchondral bone at an early stage. Diagnosis Based on the chronic history, clinical manifestations and x-ray findings, the diagnosis is easy. If necessary, synovial fluid examination can be done to confirm the diagnosis. X-ray changes do not indicate primary osteoarthrosis. It should be clear from the medical history whether the lesion is primary or secondary. Differential diagnosis 1. Rheumatoid arthritis Most often occurs in the age of 20 to 50 years. Severe acute attacks, with mild systemic symptoms and long duration. The affected joints are mostly symmetrical or multiple, without invading the distal interphalangeal joints. The joints are swollen and pyknotic in the early stages, with dysfunction and ankylosing deformity in the late stages. x-ray examination of local or generalized osteoporotic joint surface resorption bony healing ankylosing deformity. Laboratory tests increased blood sedimentation, rheumatoid factor positive. 2, ankylosing spondylitis Most often occurs in young adults aged 15-30 years old male. Slow onset, intermittent pain, multi-joint involvement. The spine activity is limited, joint deformity, morning stiffness. x-ray examination of the sacroiliac joint space narrowing vague, spinal ligament calcification, bamboo-like changes. Laboratory tests include increased or normal blood sedimentation and positive for HLA-B27. Rheumatoid factor is mostly negative. Treatment The main treatment for this disease is to reduce the weight-bearing of joints and excessive and substantial activities to slow down the process of lesions. Obese patients should lose weight to reduce the load on the joints. In the case of lower limb joints, crutches or canes can be used to reduce the burden on the joints. Physical therapy and appropriate exercise can maintain the range of motion of the joints, and splinting supports and canes can be used when necessary to help control symptoms in the acute phase. Anti-inflammatory and analgesic drugs can reduce or control symptoms. In advanced cases, artificial joint replacement is an effective method to eliminate pain, correct deformity and improve function, and can greatly improve the quality of life of patients if the systemic condition can tolerate the surgery.