498 - Clinical Outcomes of Lumbar Fusion Using a Truss Technology Based Inte...

#498 Clinical Outcomes of Lumbar Fusion Using a Truss Technology Based Interbody Fusion Cage

Cutting Edge Innovations/Non-conventional Therapies

Poster Presented by: C. Carmody

Author(s):

C. Carmody (1)
D.D. Ohnmeiss (2)

(1) Plano Orthopedic and Sports Medicine Center, Plano, TX, United States
(2) Texas Back Institute Research Foundation, Plano, TX, United States

Abstract

Introduction: Spinal fusion is a complex process involving many factors including intricate relationships between spinal loading, structural support, and growth of bone cells. Interbody device design should incorporate these factors to optimize fusion incorporation. Trusses composed of triangular units provide strong structural support in loading conditions, but also allow load transfer throughout a multiplanar truss structure. This loading should stimulate of bone cell growth needed for fusion and the trusses provide a scaffold for bone growth to occur. This concept has been applied to designing a three-dimensional titanium truss device for lumbar interbody fusion. The purpose of this study was to evaluate the clinical outcomes of patients undergoing lumbar fusion using a truss technology based interbody fusion cage.

Methods: The study was based on the consecutive series of 22 patients beginning with first case experience using the ALIF Spinal Truss System (4WEB, Inc.) combined with posterior pedicle screws. Graft material used in the cages was bone marrow aspirate combined with allograft or a bone graft extender. No BMP was used. All patients had failed to gain adequate relief from non-operative care and the msot common diagnoses were painful disc degeneration and spondylolisthesis. Eleven patients were operated at one level, 10 at two levels, and one at three levels. Mean follow-up was 6.3 months (range 3-12 months). Clinical outcome was evaluated based on Oswestry Disability Index (ODI), visual analog scale (VAS) assessing pain, and occurrence of complications and/or re-operations. Fusion was assessed from radiographs and CT scans made at 6 months after surgery (missing for one patient).

Results: There was statistically significant improvement in ODI scores, from a mean of 41.5 pre-operatively to 21.2 post-operatively (p< 0.01; paired t-test). The VAS score assessing pain also improved significantly (6.4 vs. 2.8; p< 0.01). All patients were classified as fused based on plain films and CT evaluation at the 6 month follow-up (Figures 1 and 2). There was one re-operation to perform laminotomy four weeks after the index operation for persistent leg pain.

Discussion: This study found that patients had significantly improved pain and function scores following fusion. All patients reachiung 6 month follow-up were fused based on CT. Based on this early experience, it appears that the truss technology based interbody device is associated with good clinical outcomes. The favorable fusion rate may be related to truss design that was established in earlier pre-clinical studies as a loading and scaffold environment favorable for cellular bone growth. Certainly more patients and longer follow-up are needed to fully evaluate this technology.

Figure 1. Fusion in the interbody cage.

Figure 2. Boney incorporation through the trusses.