Ex vivo biomechanical testing of a three-dimensional printed titanium plate and spacer construct and 4.5 mm locking compression plate for ventral cervical fusion of C4-C5 in the horse.

Abstract

Objective: To compare the biomechanical properties of a three-dimensional (3D) printed titanium plate and spacer (3DM) and a 4.5 mm broad locking compression plate (LCP) for intervertebral fusion of C4-C5 in the horse.

Study design: Ex vivo experimental study.

Animals: Twenty-four equine cadaveric cervical spines.

Methods: Twenty-four cadaver equine cervical spines were randomly assigned to ventral intervertebral fusion with either 3DM (n = 12) or LCP (n = 12) at C4-C5. Four-point bending tests were performed in flexion (3DM n = 6, LCP n = 6) and extension (3DM n = 6, LCP n = 6) in a single cycle to failure. Yield, failure moment, and stiffness in flexion and extension were compared between the 3DM and LCP groups using a mixed effects linear regression model. Failure mode was compared using penalized logistic regression. The significance level was p ≤ .05.

Results: Yield, failure moment, and stiffness were similar between LCP and 3DM groups, with no differences in either flexion or extension. In extension, displaced fractures (p = .03) and screw pullout (p = .09) were more common in the LCP group.

Conclusion: The 3DM group had similar yield, failure moment, and stiffness to the LCP group. The LCP constructs were more likely to fail by screw pullout or displaced vertebral fracture in extension. Sample size was a major limitation, so smaller differences in the mechanical variables and failure mode would not have been detected.

Clinical significance: In a cadaver model, the 3DM construct was less likely to fail by displaced fracture when loaded in extension. This warrants in vivo investigation.