Osteoarthritis (Degenerative Joint Disease)

– A chronic degenerative disease process occurring primarily in the hips and knees and characterized by deterioration of the joint cartilage, formation of new bone in subchondral areas and joint margins, and joint hypertrophy.

Causes and Incidence

The etiology is unknown but is believed to be related in some way to aging and genetics. Osteoarthritis is the most common of all articular disorders, affecting more than 50 million Americans. Men and women are equally affected, but the onset in men occurs earlier. In women, the incidence increases after menopause.

Disease Process

The water content of the hyaline cartilage increases, and the protein-carbohydrate molecules decrease. The cartilage becomes softer and sheds flakes into the joint. The shedding rubs away the cartilage and increases the friction coefficient in the joint, setting up an erosive cycle. As the cartilage erodes, underlying bone is exposed. Fibrous tissue forms in the joint capsule, causing inelasticity and limiting joint movement. New bone, formed in the subchondral area and at joint margins, is stiff and subject to microfractures and callus formation. Deterioration of the weight-bearing surface combined with the bony overgrowth leads to joint hypertrophy and deformity.

Symptoms

Early
Deep, aching joint pain that is aggravated by exercise and that worsens as the day progresses; stiffness following inactivity.

Midcourse
Reduced joint motion, tenderness, crepitus, grating sensation, flexion contractures, joint enlargement.

Late
Tenderness on palpation, pain with passive range of motion, increase in degree and duration of pain, joint deformity and subluxation.

Potential Complications

Osteoarthritis of the spine can cause compression of the spinal cord, leading to weakness in the extremities, incontinence of bowel and bladder, and impotence.

Diagnostic Tests

Clinical evaluation
Any of above manifestations; Heberden’s or Bouchard’s nodules of finger joints.

Gait analysis
Altered motion patterns.

Radiology
Narrowed joint space; increased density of subchondral bone; pseudocysts in subchondral marrow; osteophytes at joint periphery.

Erythrocyte sedimentation rate
Normal/moderate increase.

Synovial analysis
High viscosity; yellow, transparent color; negative culture; WBC 2002,000/{micro};l; ,25 polymorphonuclear leukocytes.

Treatments

Surgery
Osteotomy, laminectomy, fusion, total joint replacement if conservative therapy fails.

Drugs
Aspirin, nonsteroidal antiinflammatory drugs, muscle relaxants.

General
Exercise: isometric, isotonic, isokinetic, strengthening, stretching, range of motion, balance exercise; rest; massage, moist heat for pain; elastic bandages for support; canes, walkers to aid mobility Teaching: avoid soft chairs, recliners, pillows under knees; use firm bed and hard chairs; wear sturdy, lowheeled shoes.

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