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Load-sharing between anterior and posterior elements in a lumbar motion segment implanted with an artificial disc
A P Dooris1, V K Goel, N M Grosland
1Iowa Spine Research Center, Departments of Biomedical Engineering andOrthopaedics, University of Iowa, Iowa City, Iowa, USA.
Spine
|March 14, 2001
Summary
Artificial disc implantation significantly alters spinal biomechanics. Posterior placement reduces facet joint loads, while anterior placement increases them, offering surgeons control over load distribution.
Area of Science:
- Spinal biomechanics
- Finite element analysis
- Orthopedic surgery
Background:
- Limited biomechanical data exists on posterior element loads after artificial disc implantation.
- Understanding these changes is crucial for optimizing spinal fusion and disc replacement outcomes.
Purpose of the Study:
- To evaluate the biomechanical effects of artificial disc implantation on posterior spinal elements and vertebral bodies.
- To assess how surgical variables influence these biomechanical changes.
Main Methods:
- A nonlinear 3D finite element model of the L3-L4 motion segment was utilized.
- The model was implanted with an artificial disc, simulating anterior approaches and varying implant placement.
- Simulations subjected the model to axial compression and flexion-extension moments.
Main Results:
- Facet joint loads were highly sensitive to the anteroposterior placement of the artificial disc.
- Anterior disc placement increased facet loads 2.5-fold compared to the intact model.
- Posterior disc placement resulted in no facet loads under compression and increased spinal flexibility.
Conclusions:
- Surgeons can modulate spinal stiffness and posterior load-sharing by adjusting artificial disc placement.
- Restoring the anterior longitudinal ligament effectively reduced stress on posterior elements.