Biomechanical evaluation of occipitocervical fixation devices

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Spinal Instrumentation

Background:

• Occipitocervical fixation is crucial for stabilizing the upper spine.
• Traditional wiring techniques have limitations in providing adequate stability.
• Modern plate and screw systems aim to improve fixation outcomes.

Purpose of the Study:

• To biomechanically compare the stiffness and failure mechanisms of three occipitocervical instrumentation systems.
• To evaluate modern plate systems against traditional rod and wire constructs.

Main Methods:

• Human cadaveric occipitocervical specimens were used.
• Three instrumentation types were tested: AXIS Fixation System, Y-Plate, and Luque rectangle.
• Biomechanical testing involved compression, flexion, extension, and torsion loading modes.

Main Results:

• No significant stiffness differences were found under compression and flexion.
• Plate systems demonstrated statistically higher stiffness than the Luque rectangle in extension and torsion.
• Plate systems failed via C2 pedicle fracture in extreme flexion.

Conclusions:

• Modern plate systems provide superior stiffness and stability in extension and torsion compared to the Luque rectangle.
• Occipitocervical plate systems offer enhanced stability over traditional wiring.
• Surgeons can use this data to inform choices between modern plate/screw and traditional rod/wire constructs.