Clinical outcome results of pedicle subtraction osteotomy in ankylosing spondylitis with kyphotic deformity.

STUDY DESIGN

A prospective study was performed in 45 patients with ankylosing spondylitis.

OBJECTIVES

To assess the outcomes of decancellation pedicle subtraction extension osteotomy in ankylosing spondylitis patients with severe fixed kyphotic deformity.

SUMMARY OF BACKGROUND DATA

There have been several studies regarding correction of kyphotic deformity in ankylosing spondylitis. However, most of them concern surgical technique. There have been no reports concerning clinical results of decancellation pedicle subtraction osteotomy in ankylosing spondylitis.

METHODS

The kyphotic deformity was corrected by a one-stage pedicle subtraction extension osteotomy. Radiographic assessment for sagittal balance was performed by measuring thoracic kyphosis, lumbar lordosis, distance between the vertical line on anterosuperior point of T1 and that of S1, and sacral inclination. Chin brow-vertical angle was measured on the preoperative and postoperative clinical photograph of patients. Clinical outcomes were assessed by questionnaire measuring changes in physical function, indoor activity, outdoor activity, psychosocial activity, pain, and patient satisfaction with surgery.

RESULTS

Final follow-up radiograph showed an increase in lumbar lordosis from 10 degrees to 44 degrees (an increase of 34 degrees), whereas thoracic kyphosis remained stable from 50 degrees to 54 degrees. Sagittal imbalance significantly improved from 94 to 8 mm, whereas sacral inclination increased from 8 degrees to 24 degrees. The chin brow-vertical angle was 32.0 degrees before surgery and 0.9 degrees after surgery. Satisfactory clinical outcome was achieved; however, clinical improvements did not correlate with changes in radiologic measurements.

CONCLUSIONS

Most of the patients maintained good correction and had good clinical results. Based on the results of this study, pedicle subtraction extension osteotomy is effective for correction of kyphotic deformity in ankylosing spondylitis.