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Osteoarthritis 

Osteoarthritis

Chapter:
Osteoarthritis
Author(s):

Paul H. Brion

and Kenneth C. Kalunian

DOI:
10.1093/med/9780199204854.003.1909
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date: 24 March 2017

Osteoarthritis is the commonest form of arthritis, detectable radiographically in 80% of patients over the age of 55 and accounting for more dependency in walking and stair-climbing than any other disease. In clinical practice it is defined by the presence of joint symptoms (pain, aching, stiffness) plus evidence of structural change (including crepitus on active joint motion, bony enlargement, radiographic changes of joint space narrowing or osteophytes).

Aetiology and pathogenesis

Risk factors include being female, increasing age, obesity, family history of osteoarthritis (particularly for the hand), increased bone density, trauma, and certain occupational exposures (particularly for the knee). Early onset severe osteoarthritis has been linked to an autosomal dominant mutation in the type 2 procollagen gene (COL2A1), and mutations in other genes may also be important. There are many causes of secondary osteoarthritis, including congenital/developmental abnormalities, trauma, and metabolic and endocrine conditions.

Osteoarthritis results from an imbalance in catabolic and anabolic processes that lead to progressive cartilage damage and destruction. Early stages are characterized by increased water content and cartilage swelling, followed by fragmentation. Reparative processes, involving the formation of fibrocartilage in place of hyaline cartilage, may initially lead to joint stabilization, but ultimately contribute to disease progression by exposing subchondral bone to increased forces. Sclerosis and osteophyte formation develop.

Clinical features

Idiopathic osteoarthritis commonly involves the hands, hips, knees, and spine. Mild to moderate pain is the predominant symptom, increasing with joint use and at the end of the day, and generally improved with rest and moderation of activity. Physical examination reveals tenderness to palpation, bony thickening (osteophyte formation), small effusions, and crepitus. Specific joint findings in the hand are bony enlargement of the proximal interphalangeal joints (Bouchard’s nodes) and the distal interphalangeal joints (Heberden’s nodes), and a ‘squared’ appearance of the lateral aspect of the hand owing to involvement of the first carpometacarpal joint.

Radiographic findings include asymmetry, joint space narrowing, subchondral sclerosis, subchondral cysts, and (the hallmark) osteophytes.

Management

Treatment modalities for all forms of osteoarthritis are limited. Weight loss is effective but difficult to achieve and maintain. Physical therapy and exercise have been demonstrated to improve functional outcome and pain scores in clinical trials. Paracetamol (acetaminophen) is superior to placebo but less efficacious than nonsteroidal anti-inflammatory drugs (NSAIDs) in relieving pain. NSAIDs have been a cornerstone of treatment for many years, but recently their use has diminished because of reports of serious cardiovascular adverse effects. Intra-articular corticosteroids may be effective, but injections should be limited to three to four per year in any given joint to minimize the risk of complications.

Physical aids—a joint that is unstable and painful can be made more stable and less painful by appropriate aids. Walking sticks can be very effective; wheelchairs and other appliances may make it possible for patients to maintain their independence.

Surgical intervention—this is generally reserved for patients who have failed conservative management, including analgesics, physiotherapy, and intra-articular injection. Options include synovectomy, repair of meniscal tears, realignment osteotomy, and total joint replacement (the only known ‘cure’ for osteoarthritis).

Other proposed treatments—irrigation of osteoarthritic joints has been used as a method of relieving joint pain, but remains controversial. Intra-articular injections of hyaluronic acid preparations have become popular in recent years, but any effect is likely to be small. Many patients feel that glucosamine salts and chondroitin sulphate improve symptoms, but recent data from large randomized clinical trials do not support these claims.

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