Synovitis

Synovitis is a common disorder that mainly affects the knee joint. The knee has the most synovium, the largest articular surface, and the most complex structure of any joint in the body; because the synovium of the knee is extensive and located superficially in the limb, it has more opportunities to suffer injury and infection. Knee synovitis is mainly a syndrome caused by knee sprain and various intra-articular injuries. Knee synovitis is mainly caused by knee sprain and various intra-articular injuries, such as meniscal injury, synovial injury, and cruciate or collateral ligament injury, with intra-articular effusion or sometimes hemarthrosis, presenting as acute traumatic knee synovitis. Intra-articular injury and dislocation, and sometimes simple synovial injury, such as mild trauma or long-term chronic knee strain, together with invasion of wind, cold and dampness, can gradually cause knee swelling and dysfunction, forming chronic knee synovitis.

Common Symptoms

Knee pain; inflammatory damage; inability to fully extend the knee

Causes

Synovitis in young people. In young people, knee synovitis is mainly caused by knee sprain and various intra-articular injuries, such as meniscal injury, synovial injury, and cruciate or collateral ligament injury, with intra-articular effusion or sometimes hemarthrosis, presenting as acute traumatic knee synovitis. Intra-articular injury and dislocation, and sometimes simple synovial injury, such as mild trauma or long-term chronic knee strain, together with invasion of wind, cold and dampness, can gradually cause knee swelling and dysfunction, forming chronic knee synovitis. Another cause is infection, of which synovial tuberculosis is common; generally the synovium is rich in blood vessels with good circulation and strong resistance to bacteria, but when infected with tubercle bacillus the condition progresses slowly and symptoms fluctuate, which is one form of chronic knee synovitis. Synovitis in the elderly. Knee synovitis in the elderly is mostly secondary to knee osteoarthritis, mainly due to mechanical and biochemical stimulation from cartilage degeneration and osteophyte formation, secondarily causing synovial edema, exudation and effusion. Excessive exercise. The swollen type is mainly characterized by swelling after overexercise, with pain of varying severity; the non-swollen type is mainly characterized by joint pain, often with mild swelling. Studies confirm that the two types are essentially the same, differing only in the degree of synovial pathological change. Researchers have found that after prolonged overuse of the knee with a single motion, the synovial tissue is congested and edematous, and the exudation of red and white blood cells and fibrin is positively correlated with increased intra-articular pressure and decreased oxygen partial pressure; when the exudation rate exceeds the synovium's compensatory absorption rate, joint effusion occurs, creating a vicious cycle of continuously rising intra-articular pressure and falling oxygen partial pressure, which over time forms chronic aseptic inflammation such as synovial degeneration and fatty metaplasia; thus it is believed that after overexercise the occurrence of traumatic synovitis is related not only to repeated impact on the articular surface and injury of the joint capsule, but also plays an important role in the development and outcome of the disease. After knee synovial injury, the synovium shows congestion, edema and neutrophil infiltration. Synovial blood vessels dilate, and plasma and cells extravasate, producing a large amount of exudate; meanwhile synovial cells become active and produce a large amount of mucin. The exudate contains red blood cells, white blood cells, bilirubin, fat, mucin and fibrin; in severe cases the joint effusion is bloody. There is joint swelling and limited movement. If not treated in time, late-stage synovial hypertrophy, intra-articular adhesion and cartilage degeneration may occur. With repeated injury the synovial reaction can become chronic, showing lymphocyte and plasma cell infiltration. These are all non-specific synovial reactions. When severe injury causes synovial defects, healing is rapid because synovial cells can regenerate and proliferate, and other tissues and cells can also metaplastically become synovial cells. However, in severe hypertrophic knee arthritis, edema, hypertrophy and thickening of the synovial villi form many synovial plicae of varying sizes and shapes, fibrosis of subsynovial connective tissue, and biological aging of the synovial tissue, all of which markedly reduce the regenerative and repair capacity of the synovial tissue.

Treatment

Medication, supportive treatment, rehabilitation therapy

Prevention

(1) Avoid excessive knee activity and strain, especially for those with strenuous lower-limb exercise (such as dancers, athletes, and porters); balance work and rest, and prevent tissue injury from overexertion, otherwise osteophytes are likely to appear with age. (2) When a knee fracture occurs, seek medical attention promptly and achieve anatomical reduction of the fracture ends as much as possible; if reduction is unsatisfactory, surgical treatment should be taken in time. (3) People who are overweight should control diet appropriately, adjust diet structure, reduce calorie intake, keep weight within an appropriate range, and reduce pressure and wear on the joints. (4) The elderly may appropriately supplement calcium, vitamin D and other drugs closely related to bone metabolism, and engage in moderate physical exercise to slow the aging and degenerative changes of bone tissue.

Recommended Department

It is recommended to visit the orthopedic surgery department; before the visit you may first book an appointment and connect with experts through this platform.

Warm reminder: The above information is provided for health education reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek care at a regular hospital in time.