General Session: Adult Spinal Deformity - Hall F

Presented by: N. Anand

Author(s):

N. Anand(1), B. Khandehroo(1), S. Kahwaty(1), C. Kong(1), E. Nomoto(1)

(1) Cedars Sinai Medical Center, Spine Center, Los Angeles, CA, United States

Abstract

Introduction: A Staged CMIS approach for the correction of ASD helps fine tune and sequentially correct sagittal misalignment. Several changes were implemented to our original approach including ALIF at L5-S1, oblique LLIF approach, multi-level hyperlordotic cages and sagittal alignment assessment in between stages for correcting any residual imbalance during the second stage. This study evaluates the postop coronal and sagittal parameters obtained with staged CMIS correction of ASD.

Methods: This is a retrospective review from a prospectively collected database of 158 consecutive patients who underwent CMIS correction of ASD (Cobb angle >20 or SVA >50mm or PI/LL mismatch >10) from May 2011 till June 2017. Those without staged CMIS, a 36" film, +3 levels fused and at least 3 months FU were excluded resulting in a total of 85 patients for this study including 44 Adult idiopathic scoliosis and 41 degenerative scoliosis. In all patients multilevel lordotic LLIF with or without MIS L5-S1 ALIF were done in the first stage. The patients were ambulated after and a standing radiograph obtained two days later. Based on this radiograph further correction of alignment, as age appropriate, was planned for the second stage. This was three days later where MIS pedicle screws with aggressive rod contouring and derotation/translation was done. Indirect decompression of stenosis was documented by clinical relief of leg pain after the first stage. MIS TLIF was done at L5-S1 if an ALIF was not possible (figure 1). Radiographic parameters including SVA, LL, PI, PT, SS and PI/LL mismatch were evaluated preop, after the first stage (intra-op) and at 3-6 month post-op.

Results: Mean age was 67.5 years (45-85) with mean follow-up of 36 months (3 -75). An average of 7.1 levels (3-16) was fused. Table1 show the radiographic outcomes. The mean preoperative radiographic parameters showed a significant change in coronal Cobb angle, SVA, LL, PI/LL mismatch, pelvic tilt and sacral slope following lateral interbody fusion at the first stage (IF ± ALIF) (p< 0.05). Also the change of intra-op spinopelvic measures were significant for Cobb angle, SVA, PT and SS after the second stage of CMIS correction (p< 0.05). However, the changes of intra-op LL and PI/LL mismatch after the second stage did not reach the statistical significance. Table 2 compares these radiologic outcomes in AIS vs. Degenerative scoliosis patients.

Conclusion: Significant Improvements in radiographic scores for SVA and spinopelvic parameter suggest that a strategic staged CMIS approach may help improve radiographic outcomes in ASD.

Figure 1

Tables