Osteoarthritis (Degenerative Joint Disease)
Osteoarthritis (OA) is a disease characterized by progressive loss of articular cartilage, appositional new bone formation in the subchondral trabeculae, and formation of new cartilage and new bone at the joint margins. The exact mechanisms by which primary osteoarthritis develops are unknown.
Secondary osteoarthritis is applied to the disease when it appears in response to some local or systemic pathology (disease process).
As far as pathology is concerned, the cartilage appears thicker than normal. An increase in water content leads to swelling of cartilage and an increase in the net rate of proteoglycan (any of a group of glycoproteins (class of protein) present in connective tissue and formed of subunits of disaccharides linked together and joined to a protein core. It serves as a binding or cementing material.) synthesis. The integrity of joint surface is lost and this leads to exposed bone.
Some symptoms include pain early after joint uses, particularly after prolonged activity of the joint and is relieved by rest. As the disease progresses, pain occurs at rest. One may have stiffness or muscle spasms.
One may experience tenderness on one side of the body and pain on joint range of motion. There may be joint enlargement due to bone proliferation, spurs, chronic synovitis (inflammation of synovial membrane) or effusion (escape of fluid into a part). One can have pain on passive range of motion and crepitus (crackling sound).
Xrays or radiographs appear normal in early stages, but may also show uneven joint space narrowing, marginal osteophytes (spurs), bone cysts and joint mice (loose osseous bodies).
Nonspecific synovial fluid reveals minimal abnormalities if any.
Primary OA's cause is unknown. In the hands one may see Heberden's nodes at the distal interphalangeal joints and Bouchard's nodes at the poriximal interphalangeal joints. In the feet one can have OA at the 1st metatarsophalangeal joint. OA is also seen in the knees, hips, and spine.
Secondary OA is caused by a local or systemic pathology. There may be trauma (post-traumatic joint malalignment). It may be due to metabolic or endocrine processes such as acromegaly(abnormal enlargement of the extremities of the skeleton). Another cause is Charcot joints.
Treatment includes patient education, rest, physical therapy (heat/ice, exercise, gait training), occupational therapy-splints, joint protection, assistive devices). Analgesics like asprin and acetaminophen may be used. Anti-inflammatory agents (NSAIDS, intra-articular corticosteroids) are helpful.
Surgical intervention may include correction of joint malalignment, debridement of loose bodies, spurs, osteotomy, arthrodesis (bone fusion) or partial or total joint replacement.