A 25-year-old male complains of early morning stiffness of the back lasting more than 1 hour, improved by exercise. X-ray of the sacroiliac joints shows bilateral blurring and sclerosis. HLA-B27 is positive. What radiological sign on a lateral lumbar X-ray is a late feature of this condition?
- A Bamboo spine — syndesmophytes bridging adjacent vertebrae producing a continuous bony column ✓
- B Fish mouth vertebrae — biconcave end plates from central disc herniation
- C Rugger jersey spine — alternating sclerotic and lucent vertebral bands
- D Ivory vertebra — dense sclerosis of a single vertebral body
Correct answer: A. Bamboo spine — syndesmophytes bridging adjacent vertebrae producing a continuous bony column
Explanation
Ankylosing spondylitis (AS) causes ossification of the outer annular fibres (syndesmophytes) that bridge vertebrae to produce the pathognomonic bamboo spine on plain X-ray. Sacroiliitis is the earliest and most consistent feature. Fish mouth vertebrae are seen in sickle cell disease and osteoporosis; rugger jersey spine is seen in renal osteodystrophy; ivory vertebra suggests metastasis or lymphoma.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.