Adolescent Idiopathic Scoliosis Treated by Posterior Spinal Segmental Instrumented Fusion : When Is Fusion to L3 Stable?

Objective@#: The purpose of this study was to identify risk factors for distal adding on (AO) or distal junctional kyphosis (DJK) in adolescent idiopathic scoliosis (AIS) treated by posterior spinal fusion (PSF) to L3 with a minimum 2-year follow-up. @*Methods@#: AIS patients undergoing PSF to L3 by two senior surgeons from 2000–2010 were analyzed. Distal AO and DJK were deemed poor radiographic results and defined as >3 cm of deviation from L3 to the center sacral vertical line (CSVL), or >10° angle at L3–4 on the posterior anterior- or lateral X-ray at ultimate follow-up. New stable vertebra (SV) and neutral vertebra (NV) scores were defined for this study. The total stability (TS) score was the sum of the SV and NV scores. @*Results@#: Ten of 76 patients (13.1%) were included in the poor radiographic outcome group. The other 66 patients were included in the good radiographic outcome group. Lower Risser grade, more SV-3 (CSVL doesn’t touch the lowest instrumented vertebra [LIV]) on standing and side bending films, lesser NV and TS score, rigid L3–4 disc, more rotation and deviation of L3 were identified risk factors for AO or DJK. Age, number of fused vertebrae, curve correction, preoperative coronal/sagittal L3–4 disc angle did not differ significantly between the two groups. Multiple logistic regression results indicated that preoperative Risser grade 0, 1 (odds ratio [OR], 1.8), SV-3 at L3 in standing and side benders (OR, 2.1 and 2.8, respectively), TS score -5, -6 at L3 (OR, 4.4), rigid disc at L3–4 (OR, 3.1), LIV rotation >15° (OR, 2.9), and LIV deviation >2 cm from CSVL (OR, 2.2) were independent predictive factors. Although there was significant improvement of the of Scoliosis Research Society-22 average scores only in the good radiographic outcome group, there was no significant difference in the scores between the groups. @*Conclusion@#: The prevalence of AO or DJK at ultimate follow-up for AIS with LIV at L3 was 13.1%. To prevent AO or DJK following fusion to L3, we recommend that the CSVL touch L3 in both standing and side bending, TS score is -4 or less, the L3/4 disc is flexible, L3 is neutral (<15°) and ≤2 cm from the midline and the patient is ≥ Risser 2.

Adolescent Idiopathic Scoliosis Treated by Posterior Spinal Segmental Instrumented Fusion : When Is Fusion to L3 Stable?

Objective@#: The purpose of this study was to identify risk factors for distal adding on (AO) or distal junctional kyphosis (DJK) in adolescent idiopathic scoliosis (AIS) treated by posterior spinal fusion (PSF) to L3 with a minimum 2-year follow-up. @*Methods@#: AIS patients undergoing PSF to L3 by two senior surgeons from 2000–2010 were analyzed. Distal AO and DJK were deemed poor radiographic results and defined as >3 cm of deviation from L3 to the center sacral vertical line (CSVL), or >10° angle at L3–4 on the posterior anterior- or lateral X-ray at ultimate follow-up. New stable vertebra (SV) and neutral vertebra (NV) scores were defined for this study. The total stability (TS) score was the sum of the SV and NV scores. @*Results@#: Ten of 76 patients (13.1%) were included in the poor radiographic outcome group. The other 66 patients were included in the good radiographic outcome group. Lower Risser grade, more SV-3 (CSVL doesn’t touch the lowest instrumented vertebra [LIV]) on standing and side bending films, lesser NV and TS score, rigid L3–4 disc, more rotation and deviation of L3 were identified risk factors for AO or DJK. Age, number of fused vertebrae, curve correction, preoperative coronal/sagittal L3–4 disc angle did not differ significantly between the two groups. Multiple logistic regression results indicated that preoperative Risser grade 0, 1 (odds ratio [OR], 1.8), SV-3 at L3 in standing and side benders (OR, 2.1 and 2.8, respectively), TS score -5, -6 at L3 (OR, 4.4), rigid disc at L3–4 (OR, 3.1), LIV rotation >15° (OR, 2.9), and LIV deviation >2 cm from CSVL (OR, 2.2) were independent predictive factors. Although there was significant improvement of the of Scoliosis Research Society-22 average scores only in the good radiographic outcome group, there was no significant difference in the scores between the groups. @*Conclusion@#: The prevalence of AO or DJK at ultimate follow-up for AIS with LIV at L3 was 13.1%. To prevent AO or DJK following fusion to L3, we recommend that the CSVL touch L3 in both standing and side bending, TS score is -4 or less, the L3/4 disc is flexible, L3 is neutral (<15°) and ≤2 cm from the midline and the patient is ≥ Risser 2.

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

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).

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

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).