Which two features suggest inflammatory back pain rather than mechanical back pain?

Which two features suggest inflammatory back pain rather than mechanical back pain?

• A. Morning stiffness less than 5 minutes and onset after age 60.
• B. Morning stiffness >30 minutes that improves with activity and onset before age 40.
• C. Alternating buttock pain.
• D. Pain that worsens with activity.

Answer: (B)

Inflammatory back pain tends to start in younger people and show morning stiffness that lasts a while and improves with movement. The best cue here is morning stiffness lasting more than 30 minutes combined with onset before age 40, because this pattern reflects an inflammatory process that sits behind the pain and responds to activity. In contrast, mechanical back pain usually begins later and the morning stiffness is brief, with pain more likely to worsen with activity. While alternating buttock pain can occur with inflammation, the two strongest, most specific clues in this scenario are the prolonged morning stiffness and the young onset.