Two-level pedicle subtraction osteotomy for correction of severe thoracolumbar kyphosis due to ankylosing spondylitis

English Keywords:Ankylosing spondylitis  Kyphosis deformity  Pedicle subtraction osteotomy  Sagittal balance

English Abstract:

  【Abstract】 Objectives: To analyze the clinical results of two-level pedicle subtraction osteotomy for correction of severe thoracolumbar kyphosis due to ankylosing spondylitis. Methods: From May 2009 to December 2010, 18 males with ankylosing spondylitis complicated with severe thoracolumbar kyphosis underwent two-level pedicle subtraction osteotomy, the average age at admission was 34.8 years(range, 19-47 years). Preoperative global kyphosis(GK) Cobb angle was 70°-108°(82.6°±17.5°) and the apex vertebra was at thoracolumbar region. Preoperative thoracic kyphosis(TK), thoracolumbar kyphosis(TLK) and lumbar lordosis(LL) angle was 46°-67°(55.2°±15.3°), 25°-43°(32.4°±12.6°) and (-37°)-(-11°)[(-19.5°)±10.3°], respectively. Preoperative chin-brow vertical angle at standing position was 43°-130°(67.2°±21.9°). Global sagittal imbalance was determined by C7 plumb line and its relationship with the posterior superior corner of the sacrum, and the preoperative one was 11-35cm(18.3±14.8cm). Bridwell-Dewald scale was used to evaluate the clinical outcomes. Results: The average operation time was 5.3±1.0h(3.7-6.9h), and the average blood loss was 1887.5±850.9ml(600-3000ml). Dura matter tearing was noted in 4 cases and skin infection in 1 case, 1 case developed transient neurologic deficits, but all healed after proper intervention. The average follow-up time was 33.5 months(24-48 months). The postoperative mean GK angle, chin-brow vertical angle, global sagittal imbalance was corrected to 21.3°±4.2°, 9.3°±12.8° and 3.0±4.7cm, respectively. The postoperative GK, TK, TLK, LL, chin-brow vertical angle and global sagittal imbalance improved significantly compared with the preoperative data(P<0.05), there was no significant difference between postoperation and final follow-up(P>0.05). Instrument displacement was not noted at final follow-up. All patients could walk with normal vision. Satisfactory clinical outcomes including changes of pain, social and working status were noted at final follow-up(P<0.05). Conclusions: Two-level pedicle subtraction osteotomy is a safe and effective surgical treatment for severe thoracolumbar kyphosis due to ankylosing spondylitis kyphosis, which can promote physiological sagittal spinal curvature.