Evaluation of a PEEK titanium composite interbody spacer in an ovine lumbar interbody fusion model: a biomechanical, micro-computed tomography, and histologic analyses.

Publication date: Available online 24 July 2017
Source:The Spine Journal
Author(s): Kirk C. McGilvray, Erik I. Waldorff, Jeremiah Easley, Howard B. Seim, Nianli Zhang, Raymond J. Linovitz, James T. Ryaby, Christian M. Puttlitz
Background ContextThe most commonly used materials used for interbody cages are titanium metal and polymer polyetheretherketone (PEEK). Both of these materials have demonstrated good biocompatibility. A major disadvantage associated with solid titanium cages is their radiopacity, limiting post-operative monitoring of spinal fusion via standard imaging modalities. However, PEEK is radiolucent, allowing for temporal assessment of the fusion mass by clinicians. On the other hand, PEEK is hydrophobic, which can limit bony in-growth. While both PEEK and titanium have demonstrated clinical success in obtaining a solid spinal fusion, innovations are being developed in order to improve fusion rates and create stronger constructs using hybrid additive manufacturing approaches by incorporating both materials into a single interbody device.PurposeThe purpose of this study was to examine the interbody fusion characteristic of a PEEK - titanium composite (PTC) cage for use in lumbar fusion.Study Design/SettingThirty-four mature female sheep underwent two level (L2 - L3 and L4-L5) interbody fusion using either a PEEK or PTC cage (one of each per animal). Animals were sacrificed at 0, 8, 12 and 18-weeks post-surgery.MethodsPost-sacrifice, each surgically treated functional spinal unit underwent non-destructive kinematic testing, micro-CT scanning and histomorphometric analyses.ResultsRelative to the standard PEEK cages, the PTC constructs demonstrated significant reductions in ranges of motion and a significant increase in stiffness. These biomechanical findings were reinforced by the presence of significantly more bone at the fusion site as well as in-growth into the porous endplates.ConclusionsOverall, the results indicate that PTC interbody devices could potentially lead to a more robust intervertebral fusion relative to a standard PEEK device in a clinical setting.



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