1st April 2022

A gentleman presents to his doctor with a 3-month history of lumbar back pain and stiffness

A gentleman presents to his doctor with a 3-month history of lumbar back pain and stiffness. He reports a progressive loss of all spinal movements, and upon examination has markedly reduced lateral flexion, forward flexion, extension and rotation. His mother and grandmother both have psoriatic arthritis. The doctor requests an MRI scan and pelvic X-ray. 

Which one of the following would be the SINGLE most appropriate option to indicate a diagnosis of ankylosing spondylitis? Select ONE option only.