A comparative study of three biomaterials in an ovine bone defect model

Background Polyetheretherketone (PEEK), and more recently titanium-coated PEEK, have been given serious consideration as biomaterial design choices for spinal interbody implants. Shortcomings in these materials necessitate further innovation into materials research, for example, on polyetherketoneketone (PEKK). Common complications such as surface delamination (as with titanium coating) and lack of bone apposition (as with PEEK) indicate the need for a new material that inherently displays preferable bone growth characteristics without sacrificing structural integrity. Purpose To compare three biomaterials with respect to their osseointegrative capacity. Study Design Evaluate the in vivo material characteristics of three separate biomaterials in an ovine bone defect model: PEEK, titanium-coated PEEK (Ti-coated PEEK), and 3D printed PEKK. Biomechanical, histological and radiographic testing was the basis for evaluation and material characterization. Methods Eight ovine specimens were implanted with one of each of the three types of biomaterials tested in both left and right epicondyles using a femoral bone defect model, and were sacrificed at 8 and 16 weeks. Implants were then analyzed using a push-out method, histological staining, and various radiographic tests. Industry funding was provided for the completion of this research study, followed by an independent third party review of all relevant data for publication. Results PEKK implants demonstrated bone ingrowth, no radiographic interference, no fibrotic tissue membrane formation, significant increase in bony apposition over time, and significantly higher push-out strength compared to standard PEEK. The PEKK implant displayed bone growth characteristics comparable to Ti-coated PEEK with significant improvements in implant integrity and radiographic properties. Conclusion This study found that PEKK displayed preferable characteristics when compared to PEEK and Ti-coated PEEK, and is therefore a potential alternative to their use.