Comparison of sagittal reconstruction in ankylosing spondylitis patients with kyphosis: Smith-Petersen osteotomies versus pedicle subtraction osteotomy

Abstract

Objective To compare the effects of Smith-Petersen osteotomies (SPOs) and pedicle subtraction osteotomy (PSO) on sagittal alignment in patients with thoracolumbar kyphosis secondary to anky losing spondylitis (AS).Methods The data of the 39 patients with ankylosing spondylitis of thoracic and lumbar kyphosis were retrospectively reviewed,who received SPOs or PSO orthopedic internal fixation from August 2000 to June 2010.According to the types of osteotomies,the 39 patients were categorized into 2groups.Of them,15 patients including 13 males and 2 females comprised the SPOs group,whose average age was 28.1±7.1 years,ranging from 18 to 42,whereas the other 24 patients including 20 males and 4 females comprised the PSO group,whose average age was 38.3±7.9 years,ranging from 21 to 53.Radiographic parameters were measured and compared between the two groups including thoracic kyphosis (TK),lumbar lordosis (LL),global kyphosis (GK),sagittal imbalance (SVA),pelvic incidence (PI),sacral slope (SS),and pelvic tilting (PT) before the operation,3 months after the operation,and at the last follow-up,respectively.Results Significant differences were found in terms of the improvement of LL,PT,SS,SVA and GK except that of TK and PI.Preoperatively,no significant difference was found between the two groups in TK,SVA,PT and SS except PI,GK and LL.Postoperatively,significant differences were found between the two groups in LL,GK,PT and SS.Significant differences were found between the two groups in the mean loss of correction of GK,LL,SVA,PT and SS at the last follow-up.Conclusion For patients with ankylosing spondylitis of thoracic and lumbar kyphosis,satisfactory reconstruction of spino-pelvic alignment can be obtained by PSO,whereas loss of correction occurred frequently in SPOs. Key words: Spondylitis, ankylosing; Kyphosis; Osteotomy