Macroscale undercut features present on the endplates and within the aperture of an interbody cage provide a series of anchoring points that, with new bone formation and remodelling, resulted in improved biomechanical integrity of the treated level.
Abstract
BACKGROUND CONTEXT
The interface and interactions between an interbody cage, graft material, and host bone can all participate in the fusion. Shortcomings of Poly(aryl-ether-ether-ketone) interbody cages have been addressed with novel titanium surfaces. Titanium surfaces paired with macroscale topography features on the endplates and within the aperture may provide additional benefits.
PURPOSE
To evaluate the influence of cage design parameters on interbody fusion in a large animal preclinical model.
STUDY DESIGN/SETTING
A comparative preclinical large animal model was performed to evaluate how macroscale topography features of an interbody cage can facilitate early integration between the host bone, graft material, and interbody cage and these effects on biomechanical stability and fusion.
METHODS
Forty single level interbody fusions (L4–L5) using iliac crest autograft and bilateral pedicle screw fixation were performed in adult sheep to evaluate the effect of undercut macrostructure topography features of an interbody cage on the endplates and within the aperture. Fusions were evaluated at 6 and 12 weeks (n=10 per group) using radiography, microcomputed tomography, biomechanical integrity, and histology endpoints.
RESULTS
The presence of the undercut macrostructures present on the endplates and within the aperture statistically improved biomechanical integrity at 6 and 12 weeks compared with controls. Microcomputed tomography and histology demonstrated bony interdigitation within the endplate and aperture features contributing to the improvement in properties.
CONCLUSIONS
The present study demonstrates that Poly(aryl-ether-ether-ketone) implants with titanium surfaces can be augmented by undercut macrostructures present on the endplates and within the aperture to provide opportunities for a series of anchoring points that, with new bone formation and remodelling, result in earlier and improved biomechanical integrity of the treated level.
CLINICAL SIGNIFICANCE
This preclinical study showed that bone interdigitation with the undercut macrostructures present on the endplates and within the aperture resulted in improved fusion and biomechanical stability in a clinically relevant spinal fusion model. Future clinical study is warranted to evaluate such implants’ performance in humans.
Keywords
Biomechanics
Histology
Interbody fusion
Large animal
PEEK
Titanium
Undercut macrostructures
Cited by (0)
FDA device/drug status: Approved: The features on the test article are FDA approved on PEEK SeaSpine interbody cages.
