Which of the following is a cluster of findings indicating ankylosing spondylitis?

• A. Morning stiffness lasting less than 10 minutes
• B. Pain at rest that improves with exercise
• C. Unilateral joint pain
• D. Age of onset greater than 45 years

Answer: (B)

The selection of the finding that indicates ankylosing spondylitis is particularly relevant due to the characteristic features of the condition. Pain at rest that improves with exercise is a hallmark symptom of ankylosing spondylitis. Patients typically experience stiffness and pain during periods of inactivity, especially in the morning or after prolonged sitting, which can directly improve with movement and exercise. This phenomenon is a key differentiator in terms of inflammatory back pain associated with ankylosing spondylitis compared to mechanical causes.

The other findings are less indicative of ankylosing spondylitis. For instance, morning stiffness lasting less than 10 minutes suggests a more mechanical, non-inflammatory problem as it contrasts significantly with the lengthy morning stiffness commonly seen in ankylosing spondylitis. Similarly, unilateral joint pain is not typical of ankylosing spondylitis, as this condition generally presents with bilateral symptoms and involves the sacroiliac joints early on. Finally, an age of onset greater than 45 years contradicts the usual demographic for ankylosing spondylitis, which often begins in younger adults, typically in their late teens to early 30s. Thus, the proper identification of each of these characteristics is crucial in diagnosing ank