ESSENTIALS OF DIAGNOSIS
A degenerative disorder with minimal articular inflammation.
No systemic symptoms.
Pain relieved by rest; morning stiffness brief.
Radiographic findings: narrowed joint space, osteophytes, increased subchondral bone density, bony cysts.
Osteoarthritis, the most common form of joint disease, is chiefly a disease of aging. Ninety percent of all people have radiographic features of osteoarthritis in weight-bearing joints by age 40. Symptomatic disease also increases with age. Sex is also a risk factor; osteoarthritis develops in women more frequently than in men.
This arthropathy is characterized by degeneration of cartilage and by hypertrophy of bone at the articular margins. Inflammation is usually minimal. Hereditary and mechanical factors may be involved in the pathogenesis.
Obesity is a risk factor for osteoarthritis of the knee, hand, and probably of the hip. Recreational running does not increase the incidence of osteoarthritis, but participation in competitive contact sports does. Jobs requiring frequent bending and carrying increase the risk of knee osteoarthritis (see Chapter 41-06).
Degenerative joint disease is divided into two types: (1) primary, which most commonly affects some or all of the following: the DIP and the proximal interphalangeal (PIP) joints of the fingers (eFigure 20–2), the carpometacarpal joint of the thumb, the hip, the knee (eFigure 20–3), the metatarsophalangeal (MTP) joint of the big toe, and the cervical and lumbar spine; and (2) secondary, which may occur in any joint as a sequela to articular injury. The injury may be acute, as in a fracture; or chronic, as that due to occupational overuse of a joint or metabolic disease (eg, hyperparathyroidism, hemochromatosis, ochronosis) or joint inflammation (eg, rheumatoid arthritis).
Osteoarthritis with joint space narrowing of both the distal interphalangeal joints and the proximal interphalangeal joints of the left hand. (Used, with permission, from Nicole Richman, MD.)
Osteoarthritis with medial compartment narrowing of both knees. (Used, with permission, from Nicole Richman, MD.)
The onset is insidious. Initially, there is articular stiffness, seldom lasting more than 15 minutes; this develops later into pain on motion of the affected joint and is made worse by activity or weight bearing and relieved by rest. Flexion contracture or varus deformity of the knee is not unusual, and bony enlargements of the DIP (Heberden nodes) and PIP (Bouchard nodes) are occasionally prominent (Figure 20–1). There is no ankylosis, but limitation of motion of the affected joint or joints is common. Crepitus may often be felt over the knee. Joint effusion and other articular signs of inflammation are mild. There are no systemic manifestations.