DJD has multifactorial causes. The direct cause of DJD/OA is synovial fluid, as this causes abnormal friction between the surfaces of opposing articular cartilages within a joint. In younger horses, DJD is trauma related. Trauma can occur when abnormal forces are applied to the joint (repetitive concussion, joint instability) or if normal forces are applied to diseased or damaged cartilage (synovitis/capsulitis, OCD). Chronic synovitis of a joint causes the production of poor-quality synovial fluid. This type of synovial fluid is unable to protect the articular cartilage from mechanical friction and it does not supply the articular cartilage with sufficient nutrients for optimal chondrocyte health, leading to more fragile and brittle cartilage. Over time the increased friction and concussion experienced by the articular cartilage causes in the articular surface of the cartilage. These fibrillations eventually become flaps, which may completely break free of the articular surface and float inside the joint cavity ( ). The cartilage fragment causes further irritation of the synovium and causes increased friction on other areas of the articular cartilage. Areas of exposed subchondral bone become sclerotic in response to increase friction and compression. This disease is progressive as every change in the intra-articular condition has the positive feedback effect of furthering the irritation of the synovium & cartilage. It will eventually lead to . Individuals with injury to a joint, repetitive stress on a joint, chronic synovitis conditions in a joint, are geriatric, suffer from RA or have a familial history of DJD are at a greater risk of developing degenerative joint disease. Clinically DJD resembles chronic synovitis. The clinical signs and symptoms are joint effusion, decreased range of motion, pain, , enlargement and disfiguration of the affected joint(s), stiff gait, lameness and atrophy of muscles that control the movement of the affected joint(s). Articular damage, exostosis, and ankylosis may be visible on radiographic examination of the joint with osteoarthritis.
Diagnosis can be made through clinical signs, arthroscopy and radiography.
There is no cure for DJD or OA due to the progressive nature of the disease, damage to the articular surface is considered permanent. Treatment is targeted at managing the condition, such as pain and discomfort and maintaining function. Management practices include NSAIDs, CS, IA or IM injections with HA/GAGs, weight management/diet, low impact exercises, joint supplements such as glucosamine &MSM. Symptomatic relief of may also include the application of warm hydrotherapy to affected areas, massage of compensatory muscle tension and the application of rubs or liniments to affected areas, chiropractic, shockwave & laser are also all beneficial for DJD/OA. IRAP/stem cell therapy has shown some progress in slowing the progression of DJD/OA.
Prevention includes treating any joint injury or condition promptly and appropriately to reduce/delay the development of DJD/OA later in life. The use of joint supplements or injections
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