An improved biomechanical testing protocol for evaluating spinal arthroplasty and motion preservation devices in a multilevel human cadaveric cervical model

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  • Departments of Biomedical Engineering and Neurosurgery, The University of Tennessee Health Science Center, Memphis, Tennessee
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Object

An experimental study was performed to determine the biomechanical end-mounting configurations that replicate in vivo physiological motion of the cervical spine in a multiple-level human cadaveric model. The vertebral motion response for the modified testing protocol was compared to in vivo motion data and traditional pure-moment testing methods.

Methods

Biomechanical tests were performed on fresh human cadaveric cervical spines (C2–T1) mounted in a programmable testing apparatus. Three different end-mounting conditions were studied: pinned–pinned, pinned–fixed, and translational/pinned–fixed. The motion response of the individual segmental vertebral rotations was statistically compared using one-way analysis of variance and Student-Newman-Keuls tests (p < 0.05 unless otherwise stated) to determine differences in the motion responses for different testing methods.

Conclusions

A translational/pinned–fixed mounting configuration induced a bending-moment distribution across the cervical spine, resulting in a motion response that closely matched the in vivo case. In contrast, application of pure-moment loading did not reproduce the physiological response and is less suitable for studying disc arthroplasty and nonfusion devices.

Abbreviations used in this paper:

IAR = instantaneous axis of rotation; MSU = motion segment unit; PF = pinned–fixed; PP = pinned–pinned; TPF = translational/pinned–fixed; VB = vertebral body.

Object

An experimental study was performed to determine the biomechanical end-mounting configurations that replicate in vivo physiological motion of the cervical spine in a multiple-level human cadaveric model. The vertebral motion response for the modified testing protocol was compared to in vivo motion data and traditional pure-moment testing methods.

Methods

Biomechanical tests were performed on fresh human cadaveric cervical spines (C2–T1) mounted in a programmable testing apparatus. Three different end-mounting conditions were studied: pinned–pinned, pinned–fixed, and translational/pinned–fixed. The motion response of the individual segmental vertebral rotations was statistically compared using one-way analysis of variance and Student-Newman-Keuls tests (p < 0.05 unless otherwise stated) to determine differences in the motion responses for different testing methods.

Conclusions

A translational/pinned–fixed mounting configuration induced a bending-moment distribution across the cervical spine, resulting in a motion response that closely matched the in vivo case. In contrast, application of pure-moment loading did not reproduce the physiological response and is less suitable for studying disc arthroplasty and nonfusion devices.

Abbreviations used in this paper:

IAR = instantaneous axis of rotation; MSU = motion segment unit; PF = pinned–fixed; PP = pinned–pinned; TPF = translational/pinned–fixed; VB = vertebral body.

Contributor Notes

Address reprint requests to: Denis J. DiAngelo, Ph.D., Department of Biomedical Engineering, The University of Tennessee Health Science Center, 920 Madison Avenue, Suite 1005, Memphis, Tennessee 38163.

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