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Comparison of Allograft Bone and Titanium Cages for Vertebral Body Replacement in the Thoracolumbar Spine: A Biomechanical Study

Cardenas, Raul J. MD; Javalkar, Vijayakumar MD; Patil, Shashikant MD; Gonzalez-Cruz, Jorge MD; Ogden, Alan BSME; Mukherjee, Debi PhD; Nanda, Anil MD, FACS

Neurosurgery:
doi: 10.1227/01.NEU.0000370200.74098.CC
INSTRUMENTATION: SPINE: Instrumentation Assessment
Abstract

BACKGROUND: When an anterior approach to repair a burst fracture is indicated, several devices can be used to restore spinal stability (eg, bone graft, free-standing titanium cage, and expandable titanium cage).

OBJECTIVE: We compare the biomechanical stability and prices of each of these systems.

MATERIALS AND METHODS: Eight fresh human cadaver T11 through L3 vertebral specimens were harvested and cleaned of soft tissues. T11-T12 and L2-L3 were fixed by screws. The fixed ends were then set in automotive body filler (Bondo). The prepared specimens were tested in the Biaxial Instron tester (8874, Norwood, MA) after a sequence of the following: intact, after the creation of an anterior corpectomy at L1, and after insertion of both of the 2 different titanium cages and the fibular graft. A titanium screw-and-plate anterolateral system was used to secure the construct (VANTAGE, Medtronic Sofamor Danek, Memphis, TN). The conditions of displacement testing were as follows: rotation (± 3.5°), flexion and extension, and left and right bending (± 3.5 mm). For each mode of testing, the stiffness was calculated.

RESULTS: The stiffness data, when statistically analyzed by repeated-measures analysis of variance (at P = .05 and power > 0.9), indicated no significant differences among these devices.

CONCLUSION: On the basis of this biomechanical study, the stiffness of the fibular graft was similar to that of the other metallic devices in this cadaver model.

Author Information

Department of Neurosurgery, Louisiana State University Health Sciences Center–Shreveport, Shreveport, Louisiana (Cardenas)(Javalkar)(Patil)(Gonzalez-Cruz)(Nanda)

Departments Orthopedics and Neurosurgery, Louisiana State University Health Sciences Center–Shreveport, Shreveport, Louisiana (Ogden)(Mukherjee)

Reprint requests: Anil Nanda, MD, FACS, Professor and Chairman, Department of Neurosurgery, Louisiana State University Health Sciences Center–Shreveport, 1501 Kings Hwy, PO Box 33932, Shreveport, LA 71130–3932. E-mail: ananda@lsuhsc.edu

Received, June 11, 2009.

Accepted, January 13, 2010.

Copyright © by the Congress of Neurological Surgeons