Bouchard nodes: Bony enlargement of proximal interphalangeal (PIP)
joints, often asymptomatic. Crepitus: A creaking or hook and loop (Velcro)-like sound made by a joint in motion. Typically not painful. Heberden nodes: Bony enlargement of DIP joints, often asymptomatic. Synovitis: Inflammation of the joint space characterized by redness, swelling, and tenderness to touch.
OA is the most common joint disease in adults. The disease affects women more often than men. The incidence increases sharply in the fifth and sixth decades of life. OA begins insidiously, progresses slowly, and eventually may lead to disability, recurrent falls, inability to live independently, and significant morbidity.
Patients with OA often experience joint stiffness, which occurs with activity or after inactivity ("gel phenomena") and lasts less than 15-30 minutes. This is in contrast to the morning stiffness of patients with an inflammatory arthritis (e.g., rheumatoid arthritis, which often lasts for 1-2 hours and often requires warming, such as soaking in a hot tub, to improve. Early in the disease, there are no obvious findings. There may be some crepitus (creaking sound) in the joint, and. unlike inflammatory arthritis, there is often no or minimal tissue swelling (except in the most advanced disease). Bony prominences, especially in the DIP/PIP joints, can occur later. Figure 22-1 shows a typical joint involvement in OA versus rheumatoid arthritis. Pain seen in OA typically can be reproduced with passive motion of the joint. Table 56-1 lists the patterns of typical joint involvement.
Laboratory examination typically is unremarkable; inflammatory markers such as ESR, creatinine phosphokinase (CPK), and white blood cells (WBCs) all are normal. Likewise, autoimmune studies such as antinuclear antibody (ANA), rheumatoid factor, and complement levels also are normal. If the joint is aspirated, then examination of the synovial fluid also reflects a lack of inflammation: WBCs <2000 mm3, protein <45/dL without crystals, and glucose equal to serum. X-ray evaluation in OA may show osteophytes that are the most specific finding in the disease but might not be found early. Other
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