Posterior correction and fixation without anterior fusion for pseudoarthrosis with kyphotic deformity in ankylosing spondylitis

Study Design. Retrospective review. Objective. To assess the effectiveness of posterior correction and fixation without anterior fusion for pseudarthrosis with kyphosis in patients with ankylosing spondylitis. Summary of Background Data. Anterior fusion is the current surgical treatment for pseudarthrosis with kyphosis in ankylosing spondylitis. The unique characteristic in ankylosing spondylitis is the superior ability to bridge and fuse the large anterior opening-wedge gap created by posterior osteotomy to correct the kyphosis without anterior fusion after the osteotomy site is adequately fixed. This ability may persist even if pseudarthrosis is present. Methods. A total of 30 consecutive patients with ankylosing spondylitis (mean age 41.7 years, range 29-55) underwent posterior correction and fixation without anterior fusion to treat pseudarthrosis with kyphosis. Mean follow-up was 4.7 years (range 2.2-9.1). Radiographic and clinical results and complications were assessed. Results. Local kyphosis was substantially corrected from 45.5 (range 37-68) to 7.5 (0-14), with a mean correction of 38. All patients had no evidence of nonunion on x-ray at the level of the pseudarthrosis at final follow-up. None had a notable loss of correction. No major complication occurred. There were 3 patients with neurologic deficits who had postoperative improvement. Conclusion. Posterior correction and fixation is effective for treating pseudarthrosis with kyphosis in ankylosing spondylitis. No anterior fusion procedure was necessary.