title: Transpedicular bivertebrae wedge osteotomy and discectomy in lumbar spine for severe ankylosing spondylitis.
abstract: METHODS
  A prospective study was performed in 8 patients with severe ankylosing spondylitis.
  
  
  OBJECTIVE
  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.
  
  
  BACKGROUND
  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.
authors.affiliation: Department of Orthopaedics, Chinese PLA General Hospital, Beijing, China. 301wangyan@sina.com
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Keya
authors.initials: K
authors.lastname: Mao
authors.forename: Xuesong
authors.initials: X
authors.lastname: Zhang
authors.forename: Zheng
authors.initials: Z
authors.lastname: Wang
authors.forename: Guoquan
authors.initials: G
authors.lastname: Zheng
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Kirkham B
authors.initials: KB
authors.lastname: Wood
mesh_terms: D000328:Adult; D017586:Diskectomy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000601:surgery*; D008297:Male; D010027:Osteotomy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D018579:Patient Selection; D011446:Prospective Studies; D016103:Spinal Fractures / Q000209:etiology / Q000601:surgery; D013167:Spondylitis, Ankylosing / Q000601:surgery*; D016896:Treatment Outcome