Clinical Value of Visualized Prediction of Corrective Osteotomy of Ankylosing Spondylitis

ABSTRACT

STUDY DESIGN: Retrospective study. OBJECTIVES: To evaluate the clinical value of preoperative planning via computer simulation by comparing preoperative and postoperative measurements of a patient with ankylosing spondylitis. SUMMARY OF LITERATURE REVIEW Ankylosing spondylitis is a disorder that results in a spinal deformity because chronic inflammation at the ligament attachment sites triggers ossification; it causes round fixed kyphosis. This causes limitations in not only everyday life but also social interaction because it is impossible for patients to face forward. Therefore, surgical correction is necessary. MATERIALS AND METHODS: We analyzed 38 patients (41 instances) who underwent correctional osteotomy between June 2007 and March 2014 to treat kyphosis caused by ankylosing spondylitis. We chose the appropriate operation site on the basis of preoperative simulations of osteotomy and the site for pre- and postoperative radiological evaluations conducted from the lateral view in a standing position. For the clinical evaluation, Bath Ankylosing Spondylitis Function Index (BASFI), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Hospital Anxiety and Depression Survey (HADS), and Health Locus of Control Form C Questionnaire (HLC-C) were used. RESULTS: The mean sagittal vertical axis (SVA) was improved from 123.4 mm to 66.1 mm, the mean thoracic kyphosis angle (TKA) changed from 42.2degrees to 40.1degrees, and the mean lumbar lordosis angle (LLA) improved from 16.0degrees to 28.5degrees. The correlation coefficients between the preoperative predictive value and the postoperative radiographic measurement were 0.43, 0.93, and 0.87, which were all statistically significant. CONCLUSIONS: By comparing the preoperative measurement with the postoperative radiologic score, we found that the two were correlated and that the clinical assessment improved on the basis of the visualization. Therefore, preoperative simulation of patients with ankylosing spondylitis along with a kyphotic deformity is thought to be clinically effective.