What is the most likely diagnosis?(Answered)

A 27-year-old man presents to an orthopedic surgeon complaining of back pain and
stiffness that has progressively worsened over the past 3 years. Initially, the pain was
mild and intermittent, but currently it is 6/10 even at rest. The patient is occasionally
awakened from sleep by the pain. The stiffness is worst in the morning and improves
somewhat with exercise. On examination, the patient has a marked loss of lateral fl exion
of the lumbar spine and point tenderness over the sacroiliac joints. Radiographs of the
patient’s lumbar spine are signifi cant for mild erosion and sclerosis of the subchondral
bone within the sacroiliac joint. An x-ray of the patient’s spine is shown in Figure
9-1. Relevant laboratory fi ndings are a WBC count of 7200/mm3 and erythrocyte
sedimentation rate of 113 mm/hr; results for rheumatoid factor are negative, but results
for HLA-B27 are positive.

Right Answer Is : Ankylosing spondylitis