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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.

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References

Modic, M. T., and Ross, J. S., 2007, “Lumbar Degenerative Disk Disease,” Radiology, 245, pp. 43–61. [CrossRef] [PubMed]
Crow, W. T., and Willis, D. R., 2009, “Estimating Cost of Care for Patients With Acute Low Back Pain: A Retrospective Review of Patient Records,” J. Am. Osteopath. Assoc., 109, pp. 229–233. Available at: http://www.jaoa.org/content/109/4/229.long [PubMed]
Schizas, C., Kulik, G., and Kosmopoulos, V., 2010, “Disc Degeneration: Current Surgical Options,” Eur. Cell. Mater., 20, pp. 306–315. Available at: http://www.ecmjournal.org/journal/papers/vol020/pdf/v020a25 [PubMed]
Kuslich, S. D., Ulstrom, C. L., and Michael, C. J., 1991, “The Tissue Origin of Low Back Pain and Sciatica: A Report of Pain Response to Tissue Stimulation During Operations on the Lumbar Spine Using Local Anesthesia,” Orthop. Clin. North Am., 22, pp. 181–187. [PubMed]
Deyo, R. A., Gray, D. T., Kreuter, W., Mirza, S., and Martin, B. I., 2005, “United States Trends in Lumbar Fusion Surgery for Degenerative Conditions,” Spine, 30, pp. 1441–1445. [CrossRef] [PubMed]
Stonecipher, T. K., Vanderby, R., Jr., Sciammarella, C. A., Lei, S. S., and Fisk, J. R., 1983, “The Mechanical Consequence of Failure of Ossified Union in Attempted Posterior Spinal Fusion. A Canine Model,” Spine, 8, pp. 31–34. [CrossRef] [PubMed]
Raiszadeh, R., Heggeness, M., and Esses, S. I., 2000, “Thoracolumbar Pseudarthrosis,” Am. J. Orthop., 29, pp. 513–520. [PubMed]
Raizman, N. M., O'Brien, J. R., Poehling-Monaghan, K. L., and Yu, W. D., 2009, “Pseudarthrosis of the Spine,” J. Am. Acad. Orthop. Surg., 17, pp. 494–503. [PubMed]
Benzel, E. C., Lastra, J. J., Kalfas, I., Bak, K. H., and Ferrara, L. A., 2000, “The Biomechanics of Interbody Fusion and the Shortcomings of Lumbar Fusion With Cages and Interbody Bone Dowels,” Clin. Neurosurg., 47, pp. 557–588. [PubMed]
Kowalski, R. J., Ferrara, L. A., and Benzel, E. C., 2001, “Biomechanics of Bone Fusion,” Neurosurg. Focus, 10, p. E2. [CrossRef]
Banwart, J. C., Asher, M. A., and Hassanein, R. S., 1995, “Iliac Crest Bone Graft Harvest Donor Site Morbidity. A Statistical Evaluation,” Spine, 20, pp. 1055–1060. [CrossRef] [PubMed]
Herron, L. D., and Newman, M. H., 1989, “The Failure of Ethylene Oxide Gas-Sterilized Freeze-Dried Bone Graft for Thoracic and Lumbar Spinal Fusion,” Spine, 14, pp. 496–500. [CrossRef] [PubMed]
Asselmeier, M. A., Caspari, R. B., and Bottenfield, S., 1993, “A Review of Allograft Processing and Sterilization Techniques and Their Role in Transmission of the Human Immunodeficiency Virus,” Am. J. Sports Med., 21, pp. 170–175. [CrossRef] [PubMed]
Panjabi, M., Henderson, G., Abjornson, C., and Yue, J., 2007, “Multidirectional Testing of One- and Two-Level ProDisc-L versus Simulated Fusions,” Spine, 32, pp. 1311–1319. [CrossRef] [PubMed]
Panjabi, M., Malcolmson, G., Teng, E., Tominaga, Y., Henderson, G., and Serhan, H.2007, “Hybrid Testing of Lumbar CHARITE Discs versus Fusions,” Spine, 32, pp. 959–966. [CrossRef] [PubMed]
Pearcy, M. J., Evans, J. H., and O'Brien, J. P., 1983, “The Load Bearing Capacity of Vertebral Cancellous Bone in Interbody Fusion of the Lumbar Spine,” Eng. Med., 12, pp. 183–184. [CrossRef] [PubMed]
van der Houwen, E. B., Baron, P., Veldhuizen, A. G., Burgerhof, J. G., van Ooijen, P. M., and Verkerke, G. J., 2010, “Geometry of the Intervertebral Volume and Vertebral Endplates of the Human Spine,” Ann. Biomed. Eng., 38, pp. 33–40. [CrossRef] [PubMed]
Dooris, A. P., Goel, V. K., Grosland, N. M., Gilbertson, L. G., and Wilder, D. G., 2001, “Load-Sharing Between Anterior and Posterior Elements in a Lumbar Motion Segment Implanted With an Artificial Disc,” Spine, 26, pp. E122–E129. [CrossRef] [PubMed]
Goel, V. K., Mehta, A., Jangra, J., Faizan, A., Kiapour, A., Hoy, R. W., and Fauth, A. R., 2007, “Anatomic Facet Replacement System (AFRS) Restoration of Lumbar Segment Mechanics to Intact: A Finite Element Study and In Vitro Cadaver Investigation,” SAS J., 1, pp. 46–54. [CrossRef]
Goel, V. K., Monroe, B. T., Gilbertson, L. G., and Brinckmann, P., 1995, “Interlaminar Shear Stresses and Laminae Separation in a Disc. Finite Element Analysis of the L3-L4 Motion Segment Subjected to Axial Compressive Loads,” Spine, 20, pp. 689–698. [CrossRef] [PubMed]
Vadapalli, S., Sairyo, K., Goel, V. K., Robon, M., Biyani, A., Khandha, A., and Ebraheim, N. A., 2006, “Biomechanical Rationale for Using Polyetheretherketone (PEEK) Spacers for Lumbar Interbody Fusion-A Finite Element Study,” Spine, 31, pp. E992–E998. [CrossRef] [PubMed]
Goel, V. K., Ramirez, S. A., Kong, W., and Gilbertson, L. G., 1995, “Cancellous Bone Young's Modulus Variation Within the Vertebral Body of a Ligamentous Lumbar Spine–Application of Bone Adaptive Remodeling Concepts,” J. Biomech. Eng., 117, pp. 266–271. [CrossRef] [PubMed]
Sairyo, K., Katoh, S., Sasa, T., Yasui, N., Goel, V. K., Vadapalli, S., Masuda, A., Biyani, A., and Ebraheim, N., 2005, “Athletes With Unilateral Spondylolysis Are at Risk of Stress Fracture at the Contralateral Pedicle and Pars Interarticularis—A Clinical and Biomechanical Study,” Am. J. Sports Med., 33, pp. 583–590. [CrossRef] [PubMed]
Polikeit, A., Ferguson, S. J., Nolte, L. P., and Orr, T. E., 2003, “Factors Influencing Stresses in the Lumbar Spine After the Insertion of Intervertebral Cages: Finite Element Analysis,” Eur. Spine J., 12, pp. 413–420. [CrossRef] [PubMed]
Adam, C., Pearcy, M., and McCombe, P., 2003, “Stress Analysis of Interbody Fusion–Finite Element Modelling of Intervertebral Implant and Vertebral Body,” Clin. Biomech., 18, pp. 265–272. [CrossRef]
Patwardhan, A. G., Havey, R. M., Carandang, G., Simonds, J., Voronov, L. I., Ghanayem, A. J., Meade, K. P., Gavin, T. M., and Paxinos, O., 2006, “Effect of Compressive Follower Preload on the Flexion–Extension Response of the Human Lumbar Spine,” J. Orthop. Res., 21, pp. 540–546. [CrossRef]
Yildirim, E. D., Besunder, R., Guceri, S., Allen, F., and Sun, W., 2008, “Fabrication and Plasma Treatment of 3D Polycaprolactone Tissue Scaffolds for Enhanced Cell Functions,” Virtual Phys. Prototyping, 3.

Figures

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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.

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Fig. 2

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

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Fig. 3

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

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Fig. 4

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

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Fig. 5

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

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Fig. 6

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

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Fig. 7

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

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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

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Fig. 9

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

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Fig. 10

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

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Fig. 11

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

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Fig. 12

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

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Fig. 13

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

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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

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