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  • Does Concave Versus Convex Approach Matter When Using Lateral Lumbar Interbody Fusion For Adult Degenerative Scoliosis?

    Final Number:

    Adam S. Kanter MD; Joseph M Zavatsky MD; Gregory M. Mundis MD; Zachary Tempel MD; Stacie Nguyen BS MPH; Dean Chou MD; Paul Park MD; Juan S. Uribe MD; Michael Y. Wang MD, FACS; Neel Anand MD; Robert Eastlack MD; Praveen V. Mummaneni MD; David O. Okonkwo MD, PhD; International Spine Study Group

    Study Design:

    Subject Category:

    Meeting: Congress of Neurological Surgeons 2016 Annual Meeting

    Introduction: Does Concave Versus Convex Approach Matter When Using Lateral Lumbar Interbody Fusion For Adult Scoliosis?

    Methods: A multicenter retrospective review of a MIS adult spinal deformity database with the following inclusion criteria: age>18 years, and one of the following: coronal Cobb angle (CCA)>20, SVA>5 cm, PI-LL>10 and/or PT>20. Patients were divided into two groups determined by LLIF approach: concave or convex.

    Results: 420 patients met inclusion criteria of the database, of those, 165 had complete 2-year data. Of these, 63 patients underwent MIS reconstruction (cMIS: LLIF alone and LLIF + MIS pedicle screws), 40 from the concavity and 23 from the convexity side. No differences between groups were noted in demographic, and preop or post op radiographic parameters. EBL, length of stay and, and OR time were similar. Both groups equally treated L4-5 via LLIF and chose a similar LIV. Overall complications were similar between groups. There were no significant differences in neurologic, vascular, or visceral complications. There were 8 (3 major) neurologic complications in the concavity group of which 1 required reoperation for decompression and one revision of a pedicle screw. One (minor; LFCN palsy) neurologic complication occurred in the convexity group (p=0.09). Both groups experienced significant improvement in ODI, VAS back and leg (all p<0.05), with no difference between groups.

    Conclusions: Patients undergoing cMIS surgery for adult degenerative scoliosis had equivalent complication rates, clinical and operative, with concave or convex LLIF approaches. Radiographic and clinical outcomes improved regardless of side of LLIF approach.

    Patient Care: Finding a safer approach to get to the spine will help patient outcomes.

    Learning Objectives: For minimally-invasive adult deformity surgery, there is controversy regarding whether to perform lateral lumbar interfusion fusion by approaching the curve via the concavity or the convexity. We performed a retrospective review of a prospectively collected database of MIS surgery for adult deformity surgery. Forty patients underwent LLIF via a concavity approach, 23 patients via a convexity approach. Equivalent operative and clinical complication rates, as well as radiographic and clinical outcomes, were noted for convexity and concavity approaches.


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