Spinal pseudarthrosis in advanced ankylosing spondylitis with sagittal plane deformity: clinical characteristics and outcome analysis.

STUDY DESIGN

A retrospective study of consecutive ankylosing spondylitis (AS) patients with spinal pseudarthrosis.

OBJECTIVES

To review the clinical characteristics and assess the outcomes of surgical treatment of spinal pseudarthrosis in advanced AS patients with sagittal plane deformity.

SUMMARY OF BACKGROUND DATA

There have been several reports describing the clinical findings of spinal pseudarthrosis in AS. However, few have studied the outcomes of surgical treatment of spinal pseudarthrosis with sagittal plane deformity in advanced AS patients.

METHODS

A total of 19 destructive vertebral lesions in 12 patients were reviewed. We performed Smith-Petersen osteotomy (SPO) at the same level for correction of sagittal plane deformity and anterior interbody fusion (AIF) for repair of pseudarthrosis. Pedicle subtraction osteotomy (PSO) was performed additionally at the lumbar spine in six severe kyphotic patients. Outcome variables included radiographic measurement from preoperative, immediate postoperative and follow-up films (mean, 51 months; range, 35-108 months), and clinical assessment using visual analog scale for back pain and the modified SRS outcome instruments satisfaction domain and the review of postoperative complications.

RESULTS

Clinical characteristics including trauma and inflammatory reaction were variable. The mean time for radiographic union of pseudarthrosis was 4.2 months (range, 2.5-6 months). Average correction of segmental kyphosis with SPO at the level of pseudarthrosis was 20.9 degrees (range, 5 degrees -34 degrees ) and 26.3 degrees (range, 20 degrees -32 degrees ) with lumbar PSO. Mean sagittal imbalance had improved 15.2 cm (range, 6.7-34.7 cm) at the last follow-up. All 12 patients had improvement of pain and neurologic deficit. The mean visual analog scale for pain had improved 4.8 (range, 4-7). The mean SRS score for patient satisfaction at the last follow-up was 4.6 of a possible 5. There were 7 cases of complications, including 3 cases of intraoperative dural tear, 2 cases of postoperative radiculopathy, and 1 case of wound infection. There was no permanent complication.

CONCLUSIONS

SPO at the level of pseudarthrosis was a safe and effective technique to correct sagittal imbalance without vascular complication. Surgical repair of pseudarthrosis with AIF provided successful fusion and good clinical results. For patients with lumbar hypolordosis, additional PSO was effective in restoration of sagittal balance.