Minimally invasive spine surgery for adult degenerative lumbar scoliosis
Authors: Dangelmajer Sean , Zadnik Patricia L. , Rodriguez Samuel T. , Gokaslan Ziya L. , Sciubba Daniel M. 
Published: May 2014

Object
Historically, adult degenerative lumbar scoliosis (DLS) has been treated with multilevel decompression and instrumented fusion to reduce neural compression and stabilize the spinal column. However, due to the profound morbidity associated with complex multilevel surgery, particularly in elderly patients and those with multiple medical comorbidities, minimally invasive surgical approaches have been proposed. The goal of this meta-analysis was to review the differences in patient selection for minimally invasive surgical versus open surgical procedures for adult DLS, and to compare the postoperative outcomes following minimally invasive surgery (MIS) and open surgery.

Methods
In this meta-analysis the authors analyzed the complication rates and the clinical outcomes for patients with adult DLS undergoing complex decompressive procedures with fusion versus minimally invasive surgical approaches. Minimally invasive surgical approaches included decompressive laminectomy, microscopic decompression, lateral and extreme lateral interbody fusion (XLIF), and percutaneous pedicle screw placement for fusion. Mean patient age, complication rates, reoperation rates, Cobb angle, and measures of sagittal balance were investigated and compared between groups.

Results
Twelve studies were identified for comparison in the MIS group, with 8 studies describing the lateral interbody fusion or XLIF and 4 studies describing decompression without fusion. In the decompression MIS group, the mean preoperative Cobb angle was 16.7° and mean postoperative Cobb angle was 18°. In the XLIF group, mean pre- and postoperative Cobb angles were 22.3° and 9.2°, respectively. The difference in postoperative Cobb angle was statistically significant between groups on 1-way ANOVA (p = 0.014). Mean preoperative Cobb angle, mean patient age, and complication rate did not differ between the XLIF and decompression groups. Thirty-five studies were identified for inclusion in the open surgery group, with 18 studies describing patients with open fusion without osteotomy and 17 papers detailing outcomes after open fusion with osteotomy. Mean preoperative curve in the open fusion without osteotomy and with osteotomy groups was 41.3° and 32°, respectively. Mean reoperation rate was significantly higher in the osteotomy group (p = 0.008). On 1-way ANOVA comparing all groups, there was a statistically significant difference in mean age (p = 0.004) and mean preoperative curve (p = 0.002). There was no statistically significant difference in complication rates between groups (p = 0.28).

Conclusions
The results of this study suggest that surgeons are offering patients open surgery or MIS depending on their age and the severity of their deformity. Greater sagittal and coronal correction was noted in the XLIF versus decompression only MIS groups. Larger Cobb angles, greater sagittal imbalance, and higher reoperation rates were found in studies reporting the use of open fusion with osteotomy. Although complication rates did not significantly differ between groups, these data are difficult to interpret given the heterogeneity in reporting complications between studies.