Staged osteotomy in lateral position for the treatment of severe kyphotic deformity secondary to ankylosing spondylitis: a retrospective study

Abstract

Abstract Background Patients are often complicated with severe kyphotic deformity (Cobb > 100 °) in the advanced stage of ankylosing spondylitis (AS). Corrective osteotomy based on a prone position seems to be the only effective treatment. Even with a specifically prepared folding bed, it can occasionally be challenging to prone-position AS patients with severe kyphosis. Methods 23 patients who underwent staged osteotomy in a lateral position from October 2015 to June 2017 were analyzed. In the first stage of surgery, all but one patient underwent a single-level Ponte osteotomy, which was followed by a pedicle subtraction osteotomy in the second stage. The average follow-up was 30.8 ± 4.6 months. Global kyphosis (GK), thoracic kyphosis (TK), lumbar lordosis (LL), sagittal vertical axis (SVA), osteotomized vertebra intervertebral angle (OVI), Chin-brow vertical angle (CBVA), Oswestry Disability Index (ODI) score and Scoliosis Research Society-22 Patient Questionnaire (SRS-22) were all compared pre-and post-operation. Results All kyphosis parameters were significantly improved (all P < 0.05). GK was corrected from 115.0 ± 13.4 ° to 46.5 ± 9.0 ° postoperatively, with a mean correction of 68.5 °. SVA was improved from 21.2 ± 5.1 cm to 5.1 ± 1.8 cm postoperatively. After surgery, CBVA was adjusted from 64.1 ± 23.2 ° to 5.7 ± 10.6 ° and OVI was changed from 9.0 ± 2.7 ° to -20.1 ± 5.6 °. Both the ODI and SRS-22 showed substantial improvements (all P < 0.05). Four patients with mild complications were observed perioperatively. Conclusion In AS patients with severe kyphosis, satisfactory correction can be safely achieved with staged osteotomy in the lateral decubitus position, which can not only correct the sagittal imbalance of the spine with acceptable complications but also facilitate the placement of intraoperative position.