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Rigid and flexible spinal stabilization devices: a biomechanical comparison.
Fabio Galbusera1, Chiara Maria Bellini, Federica Anasetti
1IRCCS Istituto Ortopedico Galeazzi, Milan, Italy. fabio.galbusera@polimi.it
Medical Engineering & Physics
|December 24, 2010
Summary
Surgical stabilization devices for degenerative disc disease significantly impact lumbar spine biomechanics. Device material and design critically affect load sharing and range of motion, necessitating further study for optimal treatment selection.
Area of Science:
- Biomedical Engineering
- Spine Biomechanics
- Orthopedic Surgery
Background:
- Degenerative disc disease necessitates surgical intervention using various stabilization concepts.
- Existing devices include fusion rods and dynamic stabilization systems (load-bearing or ROM-restricting).
- Understanding the biomechanical effects of different devices is crucial for treatment optimization.
Purpose of the Study:
- To investigate the biomechanical effects of different lumbar spine stabilization systems.
- To compare the performance of various rod materials and dynamic stabilization devices.
- To analyze the influence of device design and material properties on spine biomechanics.
Main Methods:
- A finite element model of the L2-L5 lumbar spine segment was utilized.
- Pedicular screws and stabilization devices (rods, dynamic systems) were simulated at L4-L5.
- Hybrid protocol loading was applied in flexion, extension, lateral bending, and axial rotation.
Main Results:
- Spine biomechanics were highly sensitive to device design and material.
- Rods significantly reduced range of motion (ROM) by over 70% in flexion/extension.
- Dynamic devices preserved motion with ROM reductions from 30% (DSS) to 50% (FlexPLUS).
- Load sharing was more influenced by material's elastic modulus than ROM.
Conclusions:
- Lumbar spine stabilization device performance varies significantly with design and material.
- A distinction between 'flexible' and 'dynamic' motion preservation devices is proposed based on ROM restriction.
- Further basic science and clinical studies are needed to determine optimal stabilization device characteristics for degenerative disc disease treatment.
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