Partial pedicle subtraction osteotomy as an alternative option for spinal sagittal deformity correction

STUDY DESIGN

A retrospective study.

OBJECTIVE

To describe the technique of a partial pedicle subtraction osteotomy (PPSO) and to report on the clinical and radiological outcomes.

SUMMARY OF BACKGROUND DATA

Numerous corrective osteotomy techniques have been reported. Until now, there has been no reported method that can achieve a correction angle between those of the Smith-Petersen osteotomy and pedicle subtraction osteotomy as a posterior closing osteotomy that can be safely performed on the thoracic spine.

METHODS

A total of 38 patients aged between 31 and 72 years, who underwent PPSO for spinal sagittal deformity correction were enrolled in this study. The mean postoperative follow-up period was 30.1 months (range, 24-36 mo). The assessments included the Oswestry Disability Index scores, immediate postoperative and 2-year postoperative correction angles, correction loss, pseudoarthrosis, and complications.

RESULTS

There were 6 patients who underwent PPSO alone and 32 patients who underwent PPSO combined with at least one other surgical procedure (PSO in 16 patients, anterior lumbar interbody fusion in 12 patients, and Smith-Petersen osteotomy in 4 patients). The level of the osteotomy was T10 in 6 patients, T11 in 15 patients, T12 in 10 patients, 1 in 4 patients, L2 in 2 patients, and L3 in 1 patient. There were significant improvements in the overall Oswestry Disability Index scores (P = 0.001). The mean postoperative correction angle immediately after the PPSO was 18.8° (range, 12.4°-26.1°) and the mean postoperative correction angle at 2 years was 18.4° (range, 11.9°-25.7°). There was no significant loss of correction found during the 2-year follow-up. There was also no pseudoarthrosis or neurological complications.

CONCLUSION

PPSO had resulted in intermediate correction rates between those of Smith-Petersen osteotomy and PSO. PPSO is considered to be a safe and reliable procedure for patients with spinal sagittal deformities even at the thoracic spine level.

LEVEL OF EVIDENCE

4.

Factors affecting clinical results after corrective osteotomy for lumbar degenerative kyphosis

Study Design

This study is a prospective, clinical study for lumbar degenerative kyphosis.

Purpose

To determine the factors affecting postoperative clinical outcomes in patients who undergo corrective osteotomy for lumbar degenerative kyphosis.

Overview of Literature

Only a small number of studies have reported clinical results for surgery for lumbar degenerative kyphosis. There are almost no studies about prognostic factors that predict postoperative clinical results.

Methods

This study involved 25 patients who were diagnosed with lumbar degenerative kyphosis and who underwent corrective osteotomy following gait analysis. A pedicle subtraction osteotomy was done at the third lumbar vertebra (L 3). Regarding the fusion level, surgery was done within a range from T10 proximally to S1 distally. Of these, for rigid fixation of a distal part, an iliac screw was used. Pain was evaluated using a 10-point pain scale and a questionnaire about activities. We also evaluated cosmesis and subjective satisfaction using a modified version of the Scoliosis Research Society Outcome-22 (SRS-22) instrument. This assessment was done using a 5-point scale which was designed by us. We assigned patients to group A (good clinical outcomes) if their postoperative pain score was lower than 4 (of 10 points) and if scores indicating activity, cosmesis and subjective satisfaction were higher than 11 (of 15 points). All other patients were assigned to group B (poor clinical outcomes).

Results

Clinical outcomes were good in 64% of patients (16/25) and poor in 36% (9/25). Regarding cosmesis and subjective satisfaction, there were significant differences between the two groups. There were also significant differences in physical factors of individual patients such as body mass index (BMI): 23.78 ± 2.79 in group A and 26.44 ± 2.75 in group B. On gait analysis, there was a significant difference in the dynamic pelvic tilt: 7.5 ± 3.3° in group A and 11.72 ± 1.89° in group B.

Conclusions

There is no correlation between preoperative degree of kyphotic deformity and clinical outcomes. The degree of anterior rotation of pelvic tilt does not change significantly; rather, compensatory mechanisms of the pelvis and BMI were found to have more influence. Because neither the degree of satisfaction with clinical outcomes nor the increased activity was relatively higher, a more sincere decision should be made before recommending corrective osteotomy for degenerative lumbar kyphosis.