Do Expandable Cages Lead to a Higher Incidence of Subsidence? Two-year Follow-up of Lateral Lumbar Interbody Fusions

Presented at SMISS Annual Forum 2018
By Dan Cohen MD
With Joseph OBrien MD, William Tally MD, Thomas Lee MD, Torrey Shirk BA, Gita Joshua MA, Charles Ledonio MD,

Disclosures: Dan Cohen MD B; Globus Medical. F; Globus Medical Joseph OBrien MD B; Globus Medical, Medtronic, Stryker. D; K2M, RTI, ISD. F; Globus Medical, Nuvasive, RTI, William Tally MD F; Globus Medical, Thomas Lee MD , Torrey Shirk BA E; Globus Medical, Gita Joshua MA E; Globus Medical, Inc., Charles Ledonio MD E; Globus Medical,

Introduction:

Minimally invasive lateral lumbar interbody fusion (LLIF) using expandable spacers has been shown to have similar positive outcomes compared to static spacers, but with lower subsidence. Expandable interbody devices are designed to be inserted at a reduced disc height and expanded to optimal height within the disc space.

Aims/Objectives:

The current study seeks to investigate the outcomes of patients treated with LLIF using an expandable interbody device, and to assess subsidence.

Methods:

Data were prospectively collected for 27 patients (at 29 operative levels) undergoing LLIF with an expandable interbody fusion implant. Patients returned for follow-up visits through 24 months. Clinical and radiographic data were collected and analyzed. Complications were recorded.

Results:

Mean age of the patients was 58.7 years, and 63% of patients were female. Twenty-two patients (77.8%) underwent 1-level surgery, and the remaining 6 patients (22.2%) underwent 2-level surgery. Oswestry Disability Index scores decreased significantly from preoperative scores at all time points. Disc height and neuroforaminal height increased significantly over preoperative heights at 6 weeks and remained significantly increased at 24 months. At 24 months, 96.4% of patients were determined to have achieved fusion. Radiographs showed no subsidence, migration, or collapse of the implant in any patient.

Conclusions:

The use of an expandable interbody device in an LLIF procedure led to positive clinical outcomes, and increased disc heights and neuroforaminal heights by 24 months. No observed subsidence in the current study lends support to the expectation that expandable implants help reduce endplate disruption.