640 - Use of a Novel 3-D Titanium Alloy Lordotic Expandable Cage Improves Se...

Oral Posters: Innovative Technologies

Presented by: M. Weinstein - View Audio/Video Presentation (Members Only)

Author(s):

M. Weinstein(1), P. Dermarkar(2)

(1) University of South Florida School of Medicine/Florida Orthopaedic Institute, Orthopaedics and Sports Medicine/Spine Center, Tampa, FL, United States
(2) University of South Florida School of Medicine, Orthopaedics and Sports Medicine, Tampa, FL, United States

Abstract

Introduction: The use of interbody cages as an adjunct to lumbar spinal fusion remains an important technique to enhance segmental stability, promote solid arthrodesis, maintain foraminal decompression, and preserve segmental lordosis. Appropriate segmental lumbar lordosis and sagittal balance is well-known to be critical for long-term patient outcomes after arthrodesis. The transforaminal interbody approach to lumbar decompression and fusion (TLIF) allows for direct visualization and decompression of the neural elements during a single procedure. However, the placement of a large anteriorly-directed interbody device from a posterior approach has inherent difficulties due to anatomic considerations required to create or maintain lordosis. In particular there is risk of damage to the neural elements during insertion, destruction of the end plates from cage impaction, potential for collapse of the disc space over time, and failure to achieve segmental lordosis. Expandable interbody devices can mitigate these risks by allowing a reduced initial cage size prior to expansion within the confines of the interbody space. A variety of expandable cages have been designed but non allow lordotic expansion with a large footprint. This study will compare the radiographic results of TLIF in patients using either a novel lordotic expandable or lordotic fixed interbody device.

Methods: 12 patients (7 male, 5 female; mean age 54.4) underwent open single-level TLIF using a titanium alloy 3D lordotic expandable cage. The cage allows up to 3mm and 10° of lordotic expansion. Pre-and postoperative pelvic parameters, lumbar lordosis L1-S1 (LL), and segmental lordosis at the operative level were measured up to 6 months post-op. These results were compared to a historical control group of patients (10 male, 4 female; mean age 58.1 (p=0.43)) who underwent open TLIF with a lordotic banana-shaped PEEK cage. All procedures were performed by the senior author.

Results: The mean expandable cage size used was 9.8 mm compared to 9.9 mm in the control group (p=0.48). However, with 3 mm of expansion the mean effective expandable cage size was 12.8 mm. This allowed for significantly larger implant in the final expanded form compared to control (p < 0.0001). The average improvement in segmental lordosis in the expandable group was 6.89° compared to 1.29° in the control (p=0.003). This superiority in segmental lordosis improvement with the expandable cage was seen in both the L4-5 disc space (mean 6.53° versus 2.31°, p=0.035)) at L5-S1 (mean 7.4° versus -1.25° (p=0.019)). The mean change in LL was 3.71° in the expandable group and 1.19° in the control (NS,p=0.088).

Conclusion: The use of a novel titanium alloy 3D lordotic expandable cage allowed for greater improvement in segmental lordosis postoperatively in patients undergoing TLIF than did the use of a static lordotic device. The expandable device also created a greater effective cage size due to its deployment within the interbody space. This improves endplate contact, provides a more anatomic fit, and results in superior segmental lordosis. Change in LL was not seen in this single-level study. Longer-term follow up will determine if LL and sagittal balance will be maintained. Further studies will evaluate clinical outcomes to determine the significance of the radiographic results seen with use of this novel device in interbody fusion.