A 22-year-old man develops the insidious onset of low back pain improved with exercise and worsened by rest. There is no history of diarrhea, conjunctivitis, urethritis, rash, or nail changes. On examination, the patient has loss of mobility with respect to lumbar flexion and extension. He has a kyphotic posture. A plain film of the spine shows sclerosis of the sacroiliac joints. Calcification is noted in the anterior spinal ligament. Which of the following best characterizes this patient’s disease process?A) He is most likely to have acute lumbosacral back strain and requires bed rest
Insidious back pain occurring in a young male and improving with exercise suggests one of the spondyloarthropathies— ankylosing spondylitis, reactive arthritis (including Reiter syndrome), psoriatic arthritis, or enteropathic arthritis. In the absence of symptoms or findings to suggest one of the other conditions and in the presence of symmetrical sacroiliitis on x-ray, ankylosing spondylitis is the most likely diagnosis. Acute lumbosacral strain would not be relieved by exercise or worsened by rest. The prognosis in ankylosing spondylitis is generally good, with only 6% dying of the disease itself. While pulmonary fibrosis and restrictive lung disease can occur, they are rarely a cause of death (cervical fracture, heart block, and amyloidosis are leading causes of death as a result of ankylosing spondylitis). Rheumatoid factor is negative in all the spondyloarthropathies. Crohn disease can cause an enteropathic arthritis, which may precede the gastrointestinal manifestations, but this diagnosis is far less likely in this case than ankylosing spondylitis.