Transpedicular bivertebrae wedge osteotomy and discectomy in lumbar spine for severe ankylosing spondylitis.

STUDY DESIGN: A prospective study was performed in 8 patients with severe ankylosing spondylitis.

OBJECTIVES: To observe the feasibility, reliability, and complications of a method of transpedicular bivertebrae wedge osteotomy and discectomy to manage the sagittal plane deformity in ankylosing spondylitis with chin-brow vertical angles beyond 90 degrees.

SUMMARY OF BACKGROUND DATA: In ankylosing spondylitis, the correction of sagittal plane deformity can be achieved by lengthening the anterior elements, shortening the posterior elements, or a combination of the 2. Neither Smith-Petersen osteotomy, nor pedicle subtraction osteotomy in 1 segment can achieve adequate correction for cases of severe ankylosing spondylitis kyphosis.

METHODS: From January 2003 to May 2007, 8 patients (3 males and 5 females) with severe ankylosing spondylitis in our institution underwent a single stage transpedicular bivertebrae wedge osteotomy and discectomy. The operation technique includes resection of the posterior elements of 2 adjacent vertebrae, resection of the inferior-posterior aspect of proximal vertebra, and the superior-posterior aspect of the distal vertebra, followed by posterior instrumentation with pedicle screws and spinal fusion. Preoperative and postoperative height, chin-brow vertical angle, sagittal balance, and sagittal Cobb angle of the vertebral osteotomy segment were documented. Intraoperative, postoperative, and general complications were registered.

RESULTS: The mean follow-up was 18.7+/-6.1 months (range: 14 to 54 mo). The mean duration of surgery was 236 minutes (range: 198 to 310 min), and the average volume of intraoperative blood loss was 2200 mL (range: 1600 to 3860 mL). The patients' height increased from 120.5+/-12.0 cm to 159.6+/-12.4 cm (P=0.000). The mean chin-brow vertical angle was improved from 102.8+/-9.7 to 19.3+/-13.9 degrees (P=0.000). The spinal sagittal Cobb angle of the vertebral osteotomy segment was corrected from kyphosis 38.6+/-16.5 degrees to lordosis 26.6+/-10.1 degrees (P=0.000). One patient with the involvement of the cervical spine suffered an extension spinal fracture at C5/6 as the operating table was extended. Translation at the osteotomy site occurred in 1 patient during the correction. Fusion of the osteotomy was achieved in all patients, and no loosening or breakage of pedicle screws was found.

CONCLUSIONS: In cases of severe ankylosing spondylitis kyphosis with chin-brow vertical angles beyond 90 degrees, a single stage transpedicular bivertebrae wedge osteotomy and discectomy is an effective corrected method of correction.