231 - Multi-expandable Cages for Minimally Invasive Posterior/Tranforaminal...

Oral Posters: MIS

Presented by: J. Coe - View Audio/Video Presentation (Members Only)

Author(s):

J. Coe(1), D. Kucharzyk(2), K. Poelstra(3), J. Ammerman(4), S. Kunwar(5)

(1) Silicon Valley Spine Institute, Campbell, CA, United States
(2) Orthopaedic, Pediatric and Spine Institute, Crown Point, IN, United States
(3) Sacred Heart Hospital on the Emerald Coast, Department of Surgery, Miramar Beach, FL, United States
(4) Washington Neurosurgical Associates/Sibley Memoiral Hospital, Washington, DC, United States
(5) Bell Neuroscience Institute, Washington Hospital Healthcare System, Fremont, CA, United States

Abstract

Introduction: A significant drawback of posterior or transforaminal lumbar interbody fusion (P/TLIF) is the smaller-sized cage (compared to ALIF/LLIF) that must be used because of the narrow access corridor. This shortcoming often limits placement of bone graft, potentially increasing risk of pseudarthrosis or cage subsidence/migration. Furthermore, degenerative conditions such as disc collapse and spondylolisthesis can make insertion of a static posterior cage challenging. The purpose of this study is to evaluate early clinical outcomes with a multi-dimensional expandable interbody device (MDE-IBD) that may be placed without impaction via a 6-8 mm cannula. The interbody cage is expanded in situ circumferentially to a diameter of ~25 mm and vertically to a height of 8 mm - 15 mm with up to 8 degrees of lordosis.

Methods: A medical chart review study to evaluate a multi-center series having MDE-IBD P/TLIF was initiated by the authors and is currently ongoing. It was hypothesized that patients would demonstrate decreased pain and improved radiological findings. All MDE-IBD were placed using minimally-invasive P/TLIF.

Results: To date, 30 patients (15 males; 30-81 years) with 6 month follow-up are included. Principal diagnoses included spinal stenosis (n=26), spondylolisthesis (n=18), radiculopathy (n=18) and herniated disc (n=13). Eighteen (60%) patients had a single-level procedure while the rest had multiple-level fusion, with the MDE-IBD placed at two levels or in conjunction with other fusion techniques. Complications included one small dural tear without CSF leak which required no repair; no neurologic or other complications were seen. At 6 months, back and leg pain were reduced, with MCID achieved by 90% of patients. In 11 patients with available ODI scores, 7 (64%) were improved >12 points. Radiculopathy was resolved in 21/22 patients and neurologic deficit in 13/17 (+3 improving) patients who presented with these conditions preoperatively. At the first postoperative visit (~2 weeks), 29 MDE-IBD levels showed improvements of 4.8±2.9 mm for average disc height and 4.5±8.7 degrees for local disc angle. Mean (±SD) change at 3 and 6 months, respectively, for average disc height were 4.2±2.7 mm and 5.6±3.5 mm, and for local disc angle were 3.6±3.7 degrees and 3.8±5.0 degrees. Regional lumbar lordosis was preserved (±10°) or improved (>10°) in 24/28 (86%) and 22/25 (88%) patients at 3 and 6 months, respectively.

Conclusion: A key advantage of a multi-expandable cage is that an anterior-sized cage footprint can be delivered through a narrow posterior surgical corridor. Early experience with MDE-IBD in minimally-invasive P/TLIF is demonstrating encouraging outcomes, including absence of nerve retraction injuries and restoration of disc height and local disc angle along with preservation or restoration of regional lumbar lordosis.