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Getting PEEK to Stick to Bone

The Development of Porous PEEK for Interbody Fusion Devices

Torstrick, F. Brennan MS*; Safranski, David L. PhD; Burkus, J. Kenneth MD; Chappuis, James L. MD, FACS§; Lee, Christopher S.D. PhD; Guldberg, Robert E. PhD*; Gall, Ken PhD; Smith, Kathryn E. PhD

doi: 10.1097/BTO.0000000000000242

Interbody fusion cages are routinely implanted during spinal fusion procedures to facilitate arthrodesis of a degenerated or unstable vertebral segment. Current cages are most commonly made from polyether-ether-ketone (PEEK) due to its favorable mechanical properties and imaging characteristics. However, the smooth surface of current PEEK cages may limit implant osseointegration and may inhibit successful fusion. We present the development and clinical application of the first commercially available porous PEEK fusion cage (COHERE) ® that aims to enhance PEEK osseointegration and spinal fusion outcomes. The porous PEEK structure is extruded directly from the underlying solid and mimics the structural and mechanical properties of trabecular bone to support bone ingrowth and implant fixation. Biomechanical testing of the COHERE device has demonstrated greater expulsion resistance versus smooth PEEK cages with ridges and greater adhesion strength of porous PEEK versus plasma-sprayed titanium coated PEEK surfaces. In vitro experiments have shown favorable cell attachment to porous PEEK and greater proliferation and mineralization of cell cultures grown on porous PEEK versus smooth PEEK and smooth titanium surfaces, suggesting that the porous structure enhances bone formation at the cellular level. At the implant level, preclinical animal studies have found comparable bone ingrowth into porous PEEK as those previously reported for porous titanium, leading to twice the fixation strength of smooth PEEK implants. Finally, two clinical case studies are presented demonstrating the effectiveness of the COHERE device in cervical spinal fusion.

*Petit Institute of Bioengineering and Biosciences, Georgia Institute of Technology

Medshape Inc.

§SpineCenterAtlanta, Atlanta

Vertera Inc., Atlanta

Hughston Clinic, Columbus, GA

Mechanical Engineering and Materials Science, Duke University, Durham, NC

Supported by the Georgia Research Alliance (RG036/2506R08), National Science Foundation (2013162284) and the National Center for Advancing Translational Sciences of the National Institutes of Health (UL1TR000454).

F.B.T., D.L.S., C.S.D.L., R.E.G., K.G., and K.E.S. own stock in Vertera Inc. J.K.B. and J.L.C. are consultants for Vertera Inc.

For reprint requests, or additional information and guidance on the techniques described in the article, please contact Kathryn E. Smith, PhD, at or by mail 1575 Northside Drive NW, Suite 440 Atlanta, GA 30318. You may inquire whether the author(s) will agree to phone conferences and/or visits regarding these techniques.

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