Laser Modified PEEK Implants as an Adjunct to Interbody Fusion: A Sheep Model

Presented at SMISS Annual Forum 2014
By Timothy Ganey PhD
With Joseph Zavatsky MD, David Briski MD,

Disclosures: Timothy Ganey PhD B; Amenida, F; Vivex Joseph Zavatsky MD B; Amendia, Biomet, Depuy, Stryker. D; Innovative Surgical Solutions, Safe Wire, Vivex. F; Biomet., David Briski MD None,

Introduction:
Advances in laser technology have been used to imprint mimetic surface patterns on PEEK implants that mirror isotropic bone in an attempt to enhance fusion. In vitro cell culture analysis suggests laser surface etching enhances the deposition of matrix and preferentially encourages the attachment of bone. We evaluated the effect of mimetic patterning on PEEK cages on fusion in a sheep model.

Aims/Objectives:
To evaluate mimetic patterning on a Polyether ether ketone (PEEK) cage as an innovative and alternative method to achieve solid interbody fusion in a sheep model.

Methods:
PEEK implants were developed using advanced laser technology to produce a surface mimetic that was analogous to isotropic bone. Following IACUC approval, identical implants were placed in 20 sheep using an anterior approach to C3-4 with supplemental plating. Sheep were divided into 4 groups: Group 1 - mimetic patterning without autograft; Group 2 - mimetic with autograft; Group 3 - no mimetic patterning with autograft; Group 4 - no patterning without autograft. Sheep were analyzed at 3 and 6 months by radiography, CT, MRI, and histopathology. Nine sheep were sacrificed at 3-months for micro-CT and histological analysis. At 6-months, the remaining 11 sheep were analyzed.

Results:
Radiographs and viable CT scans of all 20 sheep at 3-months demonstrated the greatest radiographic evidence of fusion in Group 1 (Mimetic without autograft). Micro-CT and histological data were available in the 9 sheep that were sacrificed at 3-months. Group 1 demonstrated more abundant mineralized matrix and bony attachments at the implant’s mimetic surface interface consonant with fusion. The 11 sheep available for analysis at 6-months sustained evidence of lamellar bone formation adjacent to the implant, reduction in fibrosis, and a more cellular and highly vascularized bone.

Conclusions:
Surface modification of PEEK spinal implants with a pattern and topography that mirrored isotropic bone enhanced fusion in a large animal model. In vitro cell culture analysis had suggested laser surface etching boosted the deposition of mineralized matrix and preferentially encourages the attachment of bone cells. Three-month micro-CT and histological data, extended to additional corroboration at 6-months by both radiography and histology, confirmed these findings in the sheep model. Abundant mineralized matrix and bony attachment was found at the mimetic surface interface of the implant suggesting fusion in Group 1 in this sheep model.