Novel motion preservation device for atlantoaxial instability

Area of Science:

• Orthopedics
• Biomechanical Engineering
• Spinal Surgery

Background:

• Cervical spine instability, particularly at the C1-C2 complex, poses significant challenges.
• Novel devices are needed to address instability while preserving physiological motion.

Purpose of the Study:

• To evaluate the anteroposterior (A-P) stability and flexibility of a novel motion preservation device (MPD).
• To assess the MPD's efficacy in restricting C1-C2 instability and preserving range of motion.

Main Methods:

• An in vitro biomechanical study using ten embalmed cadaveric cervical spine specimens.
• Testing included intact, Dens-removed, MPD-instrumented, and rod fixation models.
• Measurements involved anteroposterior translational forces and range of motion (ROM) under pure moments.

Main Results:

• The MPD significantly restricted A-P instability, with translational distances comparable to intact specimens.
• C1-C2 ROM with the MPD was approximately 50% of intact in flexion, extension, and axial rotation.
• Lateral bending ROM with the MPD was equivalent to intact specimens.

Conclusions:

• The novel motion preservation device effectively restricts A-P instability at the C1-C2 complex.
• The MPD demonstrates a balance between stability and motion preservation, particularly in flexion, extension, and axial rotation.