In ankylosing spondylitis (AS) with a severe fixed thoracolumbar kyphotic deformity causing the patient to be unable to look ahead while walking (chin-on-chest deformity), the definitive surgical treatment is:

• A Pedicle subtraction osteotomy (PSO) or Smith-Petersen osteotomy (SPO) at the apex of the deformity ✓
• B Posterior spinal fusion with posterior instrumentation only
• C Anterior disc excision with cage insertion at each level
• D Total disc replacement at the ankylosed segments

Explanation

Fixed thoracolumbar kyphotic deformity in AS causing chin-on-chest deformity requires corrective osteotomy — either Smith-Petersen osteotomy (opening-wedge osteotomy through posterior elements, requires disc mobility — rarely available in AS) or pedicle subtraction osteotomy (PSO, a three-column closing-wedge resection through the pedicles and vertebral body, providing up to 30-35° correction per level). PSO is the procedure of choice in AS where discs and anterior column are fused. Posterior instrumented fusion alone does not correct fixed deformity. Anterior disc excision is not applicable to ankylosed rigid segments. Total disc replacement is contraindicated in AS.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.