Osteoarthritis

© Reed Group

Risk: Increased risk for developing osteoarthritis is associated with increasing age, obesity, female sex, history of trauma or repetitive occupational trauma such as activities that require frequent bending or carrying heavy loads. Risk factors for developing secondary osteoarthritis include participation in high impact sports such as football, history of inflammatory arthritis (i.e., rheumatoid arthritis), and presence of neuromuscular or metabolic disorders. Recreational running does not contribute to degenerative joint disease. Symptoms of the disease increase with age (Hellmann). The single greatest risk factor for osteoarthritis is age; radiographic evidence of the disease is found in 30% of individuals 45 to 65 years of age and in 80% of those age 80 or older, usually without symptoms (Lozada). Between the ages of 40 and 70, women are more troubled with osteoarthritis than men; after age 70, the rates are the same (Brandt; Porter), indicating earlier onset for women believed to be due in part to hormonal changes associated with menopause.

Incidence and Prevalence: Osteoarthritis affects over 20 million individuals in the US and is the most common articular disease worldwide (Lozada); about half of adults over age 65 are affected (Lozada). Degenerative joint disease of the knee is the leading cause of chronic disability in the US (Brandt) and is more common among black women than in other groups (Lozada). Prevalence varies worldwide and differs among ethnic groups.

History: Pain is the most common presenting symptom among individuals seeking medical attention. Symptoms of osteoarthritis develop gradually. In the early stages, the only complaint may be morning stiffness that resolves within 30 minutes after starting activity. As the disease progresses, joints become swollen and painful. The pain worsens with increased activity and weight bearing throughout the day, and is relieved with rest. Range of motion may be limited. Stiffness becomes more intense. Certain movements produce a grating, grinding sound (crepitus) or a catching sensation. Some joints such as the knee may become unstable due to stretching of the ligaments that surround and support the joint, and loss of cartilage within the joint. The hip may lose its range of motion and becomes stiff and painful. Symptoms of osteoarthritis in the hip may sometimes be felt in the groin or the knee. Back pain is the most common symptom of osteoarthritis of the spine. When osteoarthritis occurs in the neck or lower back, bone overgrowth can press on the spinal nerves causing pain, numbness, and weakness in an arm or leg. The individual may report a history of specific injury years before developing symptoms.

Physical exam: In the early stages, few or no signs may be seen on physical examination. If the disease has progressed, deformity and contractures may be observed. Joints may be slightly warm to the touch and swollen from increased synovial fluid or bone overgrowth. Nodular swellings (Heberden's or Bouchard's nodes) may be felt or seen on the fingers. Knees may bend either inward (knock knees, genu valgum) or outward (bow-legs or genu varum) or may seem flexed in a fixed state (flexion contracture). Affected joints may be tender to the touch. Active and passive range of motion may cause pain. Crepitus may be present in affected joints during motion.

Tests: X-rays of the affected joints show a characteristic pattern of joint space narrowing, bony growths (spurs or osteophytes), bone cysts, and lipping at the joint surfaces. The signs visible on x-ray may not however, correlate with the individual's symptoms of pain, swelling, and stiffness. For example, an individual's knee x-rays may show large spurs, narrow joint space, and loose bodies floating in the joint. While this would indicate a longstanding problem, the individual may have had only mild symptoms or no symptoms at all. The individual may have sought medical care only after a seemingly insignificant injury or when prolonged activity aggravated the symptoms. X-rays do not reveal changes in cartilage. For this, an MRI is required, but it is not normally used for this diagnostic purpose.

Laboratory tests are done only to rule out another diagnosis and to evaluate individual’s general health status. Erythrocyte sedimentation rate, complete blood count (CBC), C-reactive protein (CRP), and antinuclear antibody test are performed if an inflammatory process is suspected. These tests usually are normal or negative in osteoarthritis. Examination of joint fluid (arthrocentesis) may be performed to rule out infection, gout, or rheumatoid arthritis. A test for rheumatoid factor (RF) also may be done to rule out rheumatoid arthritis.