There is a debate regarding the distal fusion level for degenerative lumbar scoliosis. Whether a healthy L5-S1 motion segment should be included or not in the fusion remains controversial. The purpose of this study was to determine the optimal indication for the fusion to the sacrum, and to compare the results of distal fusion to L5 versus the sacrum in the long instrumented fusion for degenerative lumbar scoliosis. A total of 45 patients who had undergone long instrumentation and fusion for degenerative lumbar scoliosis were evaluated with a minimum 2 year follow-up. Twenty-four patients (mean age 63.6) underwent fusion to L5 and 21 patients (mean age 65.6) underwent fusion to the sacrum. Supplemental interbody fusion was performed in 12 patients in the L5 group and eleven patients in the sacrum group. The number of levels fused was 6.08 segments (range 4-8) in the L5 group and 6.09 (range 4-9) in the sacrum group. Intraoperative blood loss (2,754 ml versus 2,938 ml) and operative time (220 min versus 229 min) were similar in both groups. The Cobb angle changed from 24.7°before surgery to 6.8°after surgery in the L5 group, and from 22.8°to 7.7°in the sacrum group without statistical difference. Correction of lumbar lordosis was statistically better in the sacrum group (P = 0.03). Less correction of lumbar lordosis in the L5 group seemed to be associated with subsequent advanced L5-S1 disc degeneration. The change of coronal and sagittal imbalance was not different in both groups. Subsequent advanced L5-S1 disc degeneration occurred in 58% of the patients in the L5 group. Symptomatic adjacent segment disease at L5-S1 developed in five patients. Interestingly, the development of adjacent segment disease was not related to the preoperative grade of disc degeneration, which proved minimal degeneration in the five patients. In the L5 group, there were nine patients of complications at L5-S1 segment, including adjacent segment disease at L5-S1 and loosening of L5 screws. Seven of the nine patients showed preoperative sagittal imbalance and/or lumbar hypolordosis, which might be risk factors of complications at L5-S1. For the patients with sagittal imbalance and lumbar hypolordosis, L5-S1 should be included in the fusion even if L5-S1 disc was minimal degeneration.

Purpose:To evaluate the effectiveness of posterior lumbar interbody fusion (PLIF) using a single cage and unilateral posterolateral fusion (PLF) with local bone, and to compare the clinical and radiological results with those of posterolateral lumbar fusion (PLF) with autologous iliac bone. Materials and Methods: Fifty patients with single segment degenerative lumbar disease were treated with spinal fusion. Twenty six patients, who underwent PLIF with single cage and local bone without autologous iliac bone, were classfied as the "cage group". The other 24 patients, who underwent PLF using autologous iliac bone, were classified as the "PLF group". The fusion rate, lumbar lordortic angle, segmental angle, and intervertebral disc height were compared in the radiograph between the two groups. The clinical outcomes were evaluated by the Oswestry Disability Index. Statistical analysis was performed using a T-test and Chi-Square test. Results: The bony fusion rate was 80.8% in the cage group and 83.3% in the PLF group. The intervertebral disc height was restored better in the cage group, but there was no statistical difference between the two groups (p=0.10). Average intraoperative blood loss was similar in the two groups (565 ml in the cage group vs 567 ml in the PLF group). The average operation time was longer in the cage group but the difference was not significant (146.7 min vs 134 min). In the PLF group, 22 patients experienced pain at the iliac graft donor site in the early postoperative period that persisted for more than 6 months in 5 patients. Conclusion: PLIF using a single cage and local bone for single segment degenerative lumbar disease produced satisfactory bony fusion with none of the donor site morbidity at the iliac bone.

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