OBJECTIVETo study retrospectively the efficacy and complications of combined pedicle subtraction osteotomy (PSO) and polysegmental closing wedge osteotomy for correction of the severe rigid thoracolumbar kyphotic deformity in ankylosing spondylitis (AS).

METHODSA total of 8 consecutive male patients with AS and severe thoracolumbar kyphotic deformity (mean age 32 years, range 28 - 46) were involved in this study from August 2004 to June 2007. The average preoperative Cobb angle of thoracic spine (T(1)-T(12)) was 96 degrees (range, 80 degrees - 112 degrees ), the mean preoperative angle of lumbar lordosis (L(1)-S(1)) was 10 degrees (5 degrees - 15 degrees ). The mean chin-brow angle was 47 degrees (range, 40 degrees - 58 degrees ). The average gaze angle was 43 degrees (range, 32 degrees - 50 degrees ). After preoperative assessment, single-level PSO was performed in L(3) vertebrae and two-level polysegmental closing wedge osteotomy was performed in thoracolumbar vertebrae (T(12)-L(1), L(1-2)). Radiographic and clinical results and complications were assessed.

RESULTSThe surgical time was (298.1 +/- 20.7) minutes and blood loss during the procedure was (1588.8 +/- 171.6) ml. The follow-up period was (11.5 +/- 7.7) months. The postoperative angle and the amount of correction of the thoracic and lumbar spine were 76.1 degrees +/- 9.6 degrees , 20.3 degrees +/- 1.1 degrees and 48.4 degrees +/- 4.7 degrees , 38.4 degrees +/- 4.7 degrees respectively. The postoperative chin-brow and gaze angle was 16.5 degrees +/- 4.6 degrees and 73.0 degrees +/- 5.2 degrees , respectively. The amount of correction for sagittal balance was (12.3 +/- 1.6) cm. No nerve, vascular injury, stress fracture and coronal decompensation occurred in the patients.

CONCLUSIONSCombined PSO and polysegmental closing wedge osteotomy by posterior approach only is safe and effective for correction of the severe rigid thoracolumbar kyphotic deformity in AS. The visual field is significantly improved after surgery.