Two-level pedicle subtraction osteotomy for severe thoracolumbar kyphotic deformity in ankylosing spondylitis.

Study design A retrospective clinical study. Objective To evaluate the outcomes of two-level (T12 and L3) pedicle subtraction osteotomy (PSO) for severe thoracolumbar kyphosis in ankylosing spondylitis (AS), and to discuss the surgical strategies of this surgery. Background Cases were limited on the results of twolevel PSO for correction of severe kyphosis caused by AS, nor on surgical strategies of this type of surgery.