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Biomechanical testing of three newly developed transpedicular multisegmental fixation systems
S Eggli1, F Schläpfer, M Angst
1Department of Orthopedic Surgery, University of Bern, Inselspital, Bern, Switzerland.
Summary
This study compared the rigidity of new transpedicular fixation systems to the established Cotrel-Dubousset (CD) system. Spine Fix and AO/ASIF prototype 2 demonstrated comparable or superior stiffness to the CD system, while prototype 1 was more flexible.
Area of Science:
- Biomedical Engineering
- Orthopedic Surgery
- Spinal Biomechanics
Background:
- Transpedicular fixation systems are crucial for spinal stabilization.
- Evaluating the biomechanical properties of new spinal implants is essential for clinical adoption.
- The Cotrel-Dubousset (CD) system is an established benchmark for spinal fixation rigidity.
Purpose of the Study:
- To evaluate the rigidity of three novel transpedicular fixation systems: Spine Fix, AO/ASIF prototype 1, and AO/ASIF prototype 2.
- To compare the biomechanical performance of these new systems against the established Cotrel-Dubousset (CD) system.
- To determine if advanced features in new systems compromise construct stiffness.
Main Methods:
- 216 biomechanical tests were conducted on 36 calf spine specimens.
- Load displacement was measured under various loading conditions (flexion, extension, lateral bending, axial rotation) up to 15 Nm.
- Rigidity was assessed by comparing the stiffness coefficients of each tested implant system.
Main Results:
- Spine Fix and AO/ASIF prototype 2 exhibited stiffness equal to or greater than the CD system across tested parameters.
- AO/ASIF prototype 1 showed significantly lower stiffness compared to the CD system, except in lateral bending.
- All constructs demonstrated highly linear behavior (r2 > 0.94) with high test accuracy.
Conclusions:
- The Spine Fix and AO/ASIF prototype 2 systems offer comparable or improved rigidity to the CD system.
- AO/ASIF prototype 1 presents a more flexible alternative, suitable for specific clinical scenarios.
- New transpedicular systems can incorporate advanced features without sacrificing essential spinal construct rigidity.
