Comparison of Smith-Petersen Osteotomy versus Pedicle Subtraction Osteotomy for the Correction of Fixed Sagittal Imbalance / 대한척추외과학회지

ABSTRACT

STUDY DESIGN: A retrospective study. OBJECTIVES: The purpose of this study was to compare the results between Smith-Petersen and pedicle subtraction osteotomies for fixed sagittal imbalance, and to determine the specific indications for each. LITERATURE REVIEW SUMMARY: Smith-Petersen (SPO) and pedicle subtraction osteotomies (PSO) are the techniques most commonly used to correct fixed sagittal imbalance of the spine, but there are no reports regarding the superiority of either technique. A Smith-Petersen osteotomy is an anterior opening wedge osteotomy, which hinges on the posterior edge of the intervertebral disc, while a pedicle subtraction osteotomy is a posterior closing wedge osteotomy, without distracting the anterior column, with the hinge on the anterior aspect of the vertebral body. MATERIALS AND METHODS: Thirty patients (mean age 40.1 years, range 20 ~64 years), who underwent a SPO, were compared with forty-one patients (mean age 54.5 years, range 21 ~73 years) who underwent a PSO. The SPO was carried out in more than three segments (3 SPOs) in fourteen of the SPO group. The average follow-up periods were 4.6 years, ranging from 2 to 11.5 years, and 3.8 years, ranging from 2 to 7.1 years, for the SPO and PSO groups, respectively. Patients were evaluated by standing radiographs, chart review and outcome questionnaires. RESULTS: The mean correction of the kyphotic angle at the osteotomy sites for the SPOs was 10.7 per segment, and for those with 3 SPOs and the PSO group the average total corrections were 33.0+/-9.2 and 31.7+/-9.0, respectively. However, the improvement in sagittal balance was less statistically significantly with 3 SPOs (5.5+/-4.5 cm) than with a PSO (11.2+/-7.2 cm; p<0.01). Comparing 3 SPOs to one PSO, the SPO group decompensated the patients more substantially to the concavity (p<0.02). The mean estimated blood loss (adding up all anterior and posterior surgeries) for the procedures were 1398+/-738 (1392+/-664 mL in the 3 SPO group), and 2617+/-1645 mL in the SPO and PSO groups, respectively (p<0.001; p<0.01). The total operative times for the SPO versus the PSO groups were similar, with no statistical difference. There were substantial complications in both groups, with 13 in the 30 SPO and 30 in the 41 PSO patients. In the SPO group, 1 patient had a non-union at an osteotomy site; in the PSO group, 2 patients had a non-union at an osteotomy site. The mean Oswestry score improved from 42.3+/-14.2 to 21.3+/-14.8 postoperatively at the last visit for the SPO group and, it improved from 47.9+/-15.8 preoperatively to 29.7+/-18.3 at the last visit in PSO group (p=0.35). CONCLUSIONS: When comparing 3 Smith-Petersen osteotomies to one pedicle subtraction osteotomy, the corrections of kyphosis were almost identical, but the improvement in the C7 plumb was significantly better in the PSO group. There was a significantly greater likelihood of decompensating the patient to the concavity with the 3 SPOs than with a single PSO (p<0.02). The total operative time for the SPO versus the PSO groups showed no statistical difference. However, the blood loss was substantially greater in the PSO group (p<0.001).