MIS TLIF using a Lordotic Interbody Device that Expands in both Axial and Sagittal Planes

Presented at SMISS Annual Forum 2018
By Hani Malone MD
With M. Macki , H. Zakaria , V. Chang ,

Disclosures: Hani Malone MD None M. Macki None, H. Zakaria None, V. Chang None,

Introduction:

Anterior and lateral approaches to the lumbar disc-space facilitate placement of large interbody grafts, but have the potential for approach-related complications. Minimally invasive posterior approaches have little approach-related morbidity, but access to the disc-space, and accordingly interbody device size, is limited.

Aims/Objectives:

In this study, we evaluate the safety and efficacy of implanting an interbody device with a large circular footprint through a narrow posterior surgical corridor using novel multi-directional expanding technology. We also assess the impact of implant lordosis on postoperative lumbar lordosis.

Methods:

A retrospective review was completed evaluating MIS-TLIFs performed by the senior author (RF) using a multi-directional expandable interbody device (Luna 3D Interbody, Benvenue Medical). Fluoroscopically guided percutaneous pedicle screw fixation was used to augment interbody fusion in all cases. Pre- and post-operative patient reported outcomes data, including Numeric Pain Scale (NPS) and Oswestry Disability Index (ODI), were recorded. Radiographic measurements were based on pre- and post-operative upright X-rays with flexion/extension views.

Results:

Thirty consecutive patients were treated with a MIS TLIF using the Luna device (mean follow up 369 days, 52% women, mean age 61). Lordotic implants were used in 16 (53%) of patients. All but one patient experienced improvement in pain scores (VAS pre-op mean 7.0, post-op mean 2.8, p<0.001). Disability scores improved for all patients (ODI pre-op mean 40, post-op mean 17, p<0.001). All patients with follow up >12 months (n=25) had evidence of successful arthrodesis on dynamic flexion-extension radiographs. On average, disc height was increased by 4.5 mm and when present, spondylolisthesis was reduced by 69.5% (4 mm). Lordosis at the operative level increased by a mean 3.26° and when present, PI-LL mismatch was corrected by an average of 5.31°. Implant lordosis did not have a significant impact on lumbar lordosis. Complications associated with graft placement occurred in two separate instances (1 durotomy, 1 graft migration). To date, no instances of significant graft subsidence or hardware failure have occurred.

Conclusions:

In this series, placement of a multi-expandable interbody cage via a MIS TLIF was safe and effective. Patients reported improved pain and disability scores and the procedure consistently restored disc height, reduced spondylolisthesis, and decreased PI-LL mismatch. No association was found between implant lordosis and post-operative lumbar lordosis, which may be due to insufficient study power. This study is ongoing with the intent of better understanding the clinical and radiographic outcomes that can be reliable achieved with multi-expandable interbody technology.