Biomechanical evaluation of different instrumentation for spinal stabilisation

Area of Science:

• Spine Surgery
• Biomedical Engineering
• Orthopedic Research

Background:

• Current lumbar spine fusion methods using rigid rods or plates present challenges, including excessive stiffness or inadequate stability.
• These limitations can impede bone graft healing and increase pathology in adjacent spinal levels.

Purpose of the Study:

• To develop and evaluate a novel flexible spinal fixation device offering a balance of flexibility and stability.
• To compare the biomechanical performance of flexible, semi-rigid, and rigid spinal fixation materials.

Main Methods:

• Experimental biomechanical testing of three spinal fixation material types (rigid, semi-rigid, flexible) on eighteen cadaver spinal segments.
• Testing included conditions with and without discectomy and corporectomy.
• Finite element modeling of the flexible device was performed and validated against experimental data.

Main Results:

• The flexible device demonstrated greater suppleness, mobility, and less stiffness than rigid and semi-rigid counterparts.
• Rigid devices exhibited high stability with low hysteresis, suitable for severe instability.
• Semi-rigid devices showed high stress and hysteresis, indicating potential screw-plate micromotion.

Conclusions:

• The flexible spinal fixation device shows promise for enhancing bone graft healing and reducing adjacent segment pathology.
• Its biomechanical properties suggest it may be a superior alternative to current rigid and semi-rigid systems.
• Further research should explore the influence of bone quality on device performance and clinical outcomes.