Multi-Expandable Cages for Minimally Invasive Posterior/Tranforaminal Lumbar Interbody Fusionâ€”A Preliminary Report
Presented at SMISS Annual Forum 2016
By Jeffrey Coe MD
With Donald Kucharzyk MD, Kornelis Poelstra MD, PhD, Joshua Ammerman MD, Sandeep Kunwar MD,
Disclosures: Jeffrey Coe MD Donald Kucharzyk MD A; Benvenue Medical., Kornelis Poelstra MD, PhD None, Joshua Ammerman MD A; Benvenue Medical., Sandeep Kunwar MD B; Benvenue Medical.,
A significant drawback of posterior/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 ~25 mm diameter footprint interbody device (MDE-IBD) that may be placed without impaction via a 6-8 mm cannula.
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.
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.
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.