The mechanical effects of intervertebral disc lesions
Objective. To determine the mechanical effect of individual concentric tears, radial tears and rim lesions of the intervertebral disc anulus.
Design. In vitro dynamic mechanical testing of sheep discs comparing the mechanical behaviour before and after lesion creation.
Background. Structural changes to the disc in the form of anular lesions are a feature of disc degeneration and degeneration has been related to changes in the mechanical function of the disc. However, the effect of individual lesions is unknown.
Methods. Fifteen ovine, lumbar disc body units were tested in flexion/extension, lateral bending and axial rotation. Concentric tears, radial tears and rim lesions were experimentally introduced and the motions repeated. The mechanical response after lesion creation was compared to the undamaged response.
Results. It was found that an anterior rim lesion reduced the peak resistive moment produced by the disc in extension, lateral bending and axial rotation. Concentric tears and radial tears did not affect the peak resistive moment, however, radial tears reduced the hysteresis of response in flexion/extension and lateral bending. The neutral zone was not affected by the presence of disc lesions.
Conclusions. These results show that rim lesions reduce the disc's ability to resist motion. Radial tears change the hysteresis of response indicating an altered stress distribution in the disc.
Relevance. These changes may lead to overloading of the spinal ligaments, muscles and zygapophysial joints, possibly damaging these structures. This suggests a mechanism for a cycle of degeneration that is instigated by small changes in the mechanical integrity of the intervertebral disc.
Impact and interest:
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|Item Type:||Journal Article|
|Additional Information:||For more information, please refer to the journal's website (see hypertext link) or contact the author. Author contact details: email@example.com|
|Keywords:||Anular lesions, Robotic mechanical testing, Intervertebral joints, Degeneration|
|Subjects:||Australian and New Zealand Standard Research Classification > ENGINEERING (090000) > BIOMEDICAL ENGINEERING (090300) > Biomechanical Engineering (090302)|
|Divisions:||Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering|
Current > Institutes > Institute of Health and Biomedical Innovation
|Copyright Owner:||Copyright 2004 Elsevier|
|Deposited On:||22 Jun 2007|
|Last Modified:||29 Feb 2012 23:04|
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