A. Sacroiliac (SI) joints. Early signs include local tenderness over the SI joints and tenderness with paraspinal muscle spasm at lumbosacral vertebral levels. SI joint involvement may be elicited by special maneuvers to stress the joint.
1. Lateral compression of the pelvis with both the examiner's hands will elicit pain in the involved joint(s).
2. Gaenslen's sign. The patient lies supine on the edge of the examining table with knees flexed and with one buttock over the edge. The patient lowers the unsupported leg off the table. This maneuver elicits pain in the SI joint on the same side as the lowered leg because the SI joint is stretched open, like the binding of a book.
B. Spine. Loss of spinal motion (lateral motion, flexion, and extension) occurs early in most cases, and several maneuvers can be employed to detect and then follow such changes. With progression of disease, there is typically loss of the normal lordosis, progressive kyphosis of the thoracic spine, fixed flexion of the neck, and ultimately a stooped posture with fixed flexion contractures of the hips and knees. In the Schober test (spinal forward flexion), the patient stands erect. The examiner makes marks at two points along the spine (the lumbosacral junction and a point 10 cm above). The distance between the marks is measured in maximum forward flexion. Less than 5 cm of distraction is abnormal.
C. Costovertebral involvement is reflected in decreased chest expansion, which can be measured at the fourth intercostal space in men or under the breast in women. Less than 5 cm of chest expansion during inspiration in the adult is considered reduced.
D. Extraaxial joint involvement is usually proximal and asymmetric, and it tends to cause early contractures.
E. Other signs. The signs associated with aortic regurgitation, acute iritis, and upper lobe fibrosis are not specific. Rheumatoid nodules are notably absent. Fever is seldom present, although it can occur transiently during acute flares of arthritis.
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