Does Concave versus Convex Approach Matter When using Lateral Lumbar Interbody Fusion for Adult Scoliosis?

Presented at SMISS Annual Forum 2016
By Adam Kanter MD
With Joseph M. Zavatsky MD, Gregory Mundis Jr. MD, Zachary Tempel MD, Stacie Nguyen MPH, Dean Chou MD, Paul Park MD, Juan S. Uribe MD, FACS, Michael Wang MD, Neel Anand MD, Robert K. Eastlack MD, Praveen Mummaneni MD, David Okonkwo MD, PhD, International Spine Study Group

Disclosures: Adam Kanter MD A; Nuvasive. F; Nuvasive, Zimmer., Joseph M. Zavatsky MD B; Amendia, Biomet, Depuy, Stryker. D; Innovative Surgical Solutions, Safe Wire, Vivex. F; Biomet., Gregory Mundis Jr. MD A; ISSGF, Nuvasive. B; K2M, Medicrea, Misonix, Nuvasive. C; K2M, Nuvasive. F; Nuvasive., Zachary Tempel MD None, Stacie Nguyen MPH None, Dean Chou MD F; Medtronic, Globus, Orthofix., Paul Park MD B; Biomet, Globus, Medtronic. F; Globus., Juan S. Uribe MD, FACS A; Nuvasive. B; Nuvasive. C; Nuvasive. D; Nuvasive. F; Nuvasive, Wolters Kluwer Health., Michael Wang MD B; Aesculap, Depuy, JoiMax, K2M. C; Depuy. D; Spinicity. F; Quality Medical Publishing, Neel Anand MD A; Globus Medical. B; Globus Medical, Medtronic, Theracell, GYS Tech. C; DePuy Synthes, Stryker Spine. D; Atlas Spine, Medtronic, Globus Medical, Atlas Spine, Paradigm Spine, Theracell, AF cell, Bonovo, GYS Tech. F; Elsevier, Globus Medical, Medtronic, Nuvasive., Robert K. Eastlack MD A; Nuvasive, Research Support in Unrestricted Grant from Trinity Orthopedics. B; Aesculap, Alphatec Spine, Depuy, DiFusion, DJ Orthopaedics, Invuity, K2M, Nuvasive, Seaspine, Stryker, Titan. C; Eli Lilly. D; Alphatec Spine, Carevature, DiFusion, Invuity, Nuvasive, Spine Innovations., Praveen Mummaneni MD C; Depuy, Globus Medical. D; Spinicity. F; Depuy., David Okonkwo MD, PhD F; Biomet., International Spine Study Group A; Biomet, Depuy, Innovasis, K2M, Medtronic, Nuvasive, Stryker.

University of Pittsburgh Medical Center, Pittsburgh, PA1; Spine & Scoliosis Specialist, Tampa, FL2; San Diego Spine Foundation & Scripps Clinic, San Diego, CA3; San Diego Spine Foundation, San Diego, CA4; University of California, San Francisco, San Francisco, CA5; University of Michigan, Ann Arbor, MI6; University of South Florida, Tampa, FL7; University of Miami, Miami, FL8; Cedars Sinai, Los Angeles, CA9; Scripps Clinic, La Jolla, CA10; and International Spine Study Group Foundation, Brighton, CO11


Minimally-invasive (MIS) lateral lumbar interbody fusion (LLIF) is an effective adjunct in adult degenerative scoliosis (ADS) surgery. LLIF approaches from the concavity or convexity have inherent approach-related risks and benefits. We analyzed LLIF approach-related complications and radiographic and clinical outcomes in patients with ADS. 


To determine if patients with LLIF approach from the curve convexity will have fewer complications and improved clinical outcomes.


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. 


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. 


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.