715984 - Comparison of a 3D Printed Truss-based Lateral Interbody Device to an Annular Lateral Interbody Device for Resistance to Subsidence

Thursday, February 27, 2020

2:05 PM – 2:10 PM

Location: Ballroom B

Participants should be aware of the following financial/non-financial relationships:

Ali Kiapour, PhD: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Manoj K. Kodigudla, MS: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Amey Kelkar, MS: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Lisa Ferrara, PhD: 4 Web Medical (Individual(s) Involved: Self, Products/Services: spinal products): advisory board - options; Camber Spine (Individual(s) Involved: Self, Products/Services: spinal products): advisory board

Vijay Goel, PhD: OsteoNovus (Individual(s) Involved: Self, Products/Services: Bone cement): Equity; Spinal Balance (Individual(s) Involved: Self, Products/Services: Spinal hardware): Equity

Background:
For interbody arthrodesis, there is a need for subsidence resistance especially in osteoporotic patients with poor bone quality. A device with a larger footprint can be implanted, but implantation may be limited with a minimally invasive approach. A new implant utilizing a truss-based web design is believed to resist subsidence better than typical annular designed interbodies.

Purpose:
The purpose of this study is to assess the resistance to subsidence of the truss-based, Lateral Spine Truss System™ (LSTS, 4WEB® Medical, Frisco, TX) implant under compression for load-displacement behavior versus a traditional annular design lateral lumbar interbody fusion (LLIF) implant in SawBone blocks that mimic various human bone densities. Additionally, the study is designed to compare subsidence resistance of implants with varying width and length.

MATERIALS /

Methods:
To mimic mechanical properties similar to human bone density (osteoporotic through normal), 5, 10, 15 and 20 PCF SawBone® blocks were utilized for testing. All tests were performed using an MTS® bi-axial test system in uni-axial compression. The LSTS implants were length matched to the Annular implants and included lengths of 45, 50, 55 and 60mm (each at 0° lordosis). The widths (anterior to posterior dimension) of the LSTS implants were all 18mm (small footprint) and the widths of the Annular implants were all 21mm (medium footprint). To mimic clinical subsidence displacement, a compressive load was applied to the test block at a rate of 5mm/min. The test was repeated three times for each block/implant combination. The load displacement data at 1, 2, 3 and 4mm of subsidence was collected and recorded for each test combination. Two-way ANOVA with Sidak-Bonferroni Posthoc was used for multiple comparisons and analysis of statistical significance.

Results:
The subsidence resistance at 1, 2, 3, and 4mm was greater for the Truss implants compared to the corresponding Annular implants for all matched implant lengths and across all density blocks with the adjusted P-values being <0.001 for Truss vs Annular interbodies. (Figure 1).
In foam representing the osteoporotic bone (5pcf), the small short Truss had 27% higher subsidence resistance compared to same length, wider footprint Annular cage. The difference was 52% (Truss>Annular) in longer interbodies (60mm). Similar trends were observed in test with denser bone blocks (20pcf) with the Truss cage having 32% and 68% higher subsidence resistance compared to the Annular cage for short and long constructs respectively. (Figure 2)

Conclusions:
The Truss implants had significantly higher subsidence resistance (27%-68%) compared to the wider footprint Annular cage for all SawBone block densities including those that mimic osteoporotic bone. Truss lateral device may allow a reduced implant footprint, requiring a less invasive procedure, while minimizing the risk of subsidence in osteoporotic or normal bone quality patients.

Presenting Author(s)

Ali Kiapour, PhD

Scientist
Harvard Medical School

Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Ali Kiapour, PhD

Scientist
Harvard Medical School

Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Co-Author(s)

Manoj K. Kodigudla, MS

Research Engineer
The University of Toledo

Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Amey Kelkar, MS

Research Engineer
The University of Toledo

Disclosure: I do not have any relevant financial / non-financial relationships with any proprietary interests.

Lisa Ferrara, PhD

President and Owner
OrthoKinetic Technologies

Disclosure: 4 Web Medical : advisory board - options (Status: Ongoing); Camber Spine : advisory board (Status: Ongoing)

Vijay Goel, PhD

Endowed Professor
The University of Toledo

Disclosure: OsteoNovus : Equity (Status: Ongoing); Spinal Balance : Equity (Status: Ongoing)