A Modified Staged Three-Level Pedicle Subtraction Osteotomy Approach for Severe Ankylosing Spondylitis Using CT Navigation and Ultrasonic Bone Scalpel

Pedicle subtraction osteotomy (PSO) is a well-established technique for correcting rigid spinal deformities but remains technically demanding and carries notable risks. We describe a modified three-level PSO technique utilizing CT-guided navigation and an ultrasonic bone scalpel in a patient with severe sagittal imbalance secondary to ankylosing spondylitis. The procedure achieved satisfactory deformity correction with maintained clinical and radiographic improvement at 24 months. While further experience is needed to assess its broader applicability, this case suggests that incorporating modern navigation and precision tools may help optimize the safety and efficiency of complex PSO procedures.