0
Research Papers

Biomechanical Evaluation of an Endplate-Conformed Polycaprolactone-Hydroxyapatite Intervertebral Fusion Graft and Its Comparison With a Typical Nonconformed Cortical Graft

[+] Author and Article Information
Aakash Agarwal

e-mail: Aakash.Agarwal@rockets.utoledo.edu

Vivek Palepu

e-mail: VivekPalepu@gmail.com

Anand K. Agarwal

e-mail: Anand.Agarwal@utoledo.edu

Vijay K. Goel

e-mail: Vijay.Goel@utoledo.edu

Eda D. Yildirim

e-mail: Eda.YildirimAyan@utoledo.edu
Engineering Center for Orthopaedic Research Excellence (E-CORE),
Departments of Bioengineering and Orthopaedic Surgery,
Colleges of Engineering and Medicine,
University of Toledo,
Toledo, OH 43606

1Corresponding author. Present address: 5051 Nitschke Hall MS 303, 2801 W. Bancroft St., Toledo, OH 43606-3390.

Contributed by the Bioengineering Division of ASME for publication in the JOURNAL OF BIOMECHANICAL ENGINEERING. Manuscript received September 25, 2012; final manuscript received March 4, 2013; accepted manuscript posted March 8, 2013; published online May 9, 2013. Assoc. Editor: Brian D. Stemper.

J Biomech Eng 135(6), 061005 (May 09, 2013) (9 pages) Paper No: BIO-12-1435; doi: 10.1115/1.4023988 History: Received September 25, 2012; Revised March 04, 2013; Accepted March 08, 2013

In the thoracolumbar region, between 7% and 30% of spinal fusion failures are at risk for pseudarthrosis. From a biomechanical perspective, the nonconformity of the intervertebral graft to the endplate surface could contribute to pseudarthrosis, given suboptimal stress distributions. The objective of this study was to quantify the effect of endplate-graft conformation on endplate stress distribution, maximum Von Mises stress development, and stability. The study design used an experimentally validated finite element (FE) model of the L4–L5 functional spinal unit to simulate two types of interbody grafts (cortical bone and polycaprolactone (PCL)-hydroxyapatite (HA) graft), with and without endplate-conformed surfaces. Two case studies were completed. In Case Study I, the endplate-conformed grafts and nonconformed grafts were compared under without posterior instrumentation condition, while in Case Study II, the endplate-conformed and nonconformed grafts were compared with posterior instrumentation. In both case studies, the results suggested that the increased endplate-graft conformity reduced the maximum stress on the endplate, created uniform stress distribution on endplate surfaces, and reduced the range of motion of L4–L5 segments by increasing the contact surface area between the graft and the endplate. The stress distributions in the endplate suggest that the load sharing is greater with the endplate-conformed PCL-HA graft, which might reduce the graft subsidence possibility.

FIGURES IN THIS ARTICLE
<>
Copyright © 2013 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

The validated L4–L5 finite element model showing the conformed (left) and nonconformed graft (right) with posterior instrumentation. Annulus fibrosus has not been shown to properly depict the grafts in place.

Grahic Jump Location
Fig. 2

The above figure gives a schematic representation of the difference between the endplate-conformed graft and nonconformed graft

Grahic Jump Location
Fig. 3

ROM (in degrees) during flexion and extension with different types of graft: Case Study I

Grahic Jump Location
Fig. 4

Maximum Von Mises stresses on endplates during extension (MPa): Case Study I

Grahic Jump Location
Fig. 5

Maximum Von Mises stresses on endplates during flexion (MPa): Case Study I

Grahic Jump Location
Fig. 6

Von Mises stress contours of L4 inferior endplate in extension (in MPa): Case Study I

Grahic Jump Location
Fig. 7

Von Mises stress contours of L5 superior endplate in extension (in MPa): Case Study I

Grahic Jump Location
Fig. 8

The actual contact surface area of different grafts with the endplates at the end of 7.5 Nm of flexion and extension with 400 N of follower load (in mm2): Case Study I

Grahic Jump Location
Fig. 9

ROM (in degrees) during flexion and extension with different types of grafts, augmented by posterior instrumentation: Case Study II

Grahic Jump Location
Fig. 10

Maximum Von Mises stresses on endplates during extension (MPa): Case Study II

Grahic Jump Location
Fig. 11

Maximum Von Mises stresses on endplates during flexion (MPa): Case Study II

Grahic Jump Location
Fig. 12

Von Mises stress contours of L4 inferior endplate in extension (in MPa): Case Study II

Grahic Jump Location
Fig. 13

Von Mises stress contours of L5 superior endplate in extension (in MPa): Case Study II

Grahic Jump Location
Fig. 14

The actual contact surface area of different grafts with the endplates at the end of 7.5 Nm of flexion and extension with 400 N of follower load (in mm2): Case Study II

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In