Our goals are to highlight recent developments in clinically relevant PEEK research and to stimulate hypothesis-driven investigations related to medical grade polyaryletherketones.
Fifteen presentations and posters, as well as a symposium on "Understanding and Modifying the Cell Response to PEEK" were featured at the 2009 Annual Meeting of the European Society for Biomaterials in Lausanne, Switzerland (September 7-11, 2009). The PEEK symposium took place Monday, September 7, 2009, from 2:30 to 5:00 PM. Please check out our own Symposium webpage for additional details about PEEK research highlighted at ESB.
There have been no studies about the practicability and putative safety of PEEK cages in cervical spine infection. Now, researchers from the Medical Center of Friedrich-Schiller-University present the history of five patients suffering from neurological deficits and septicemia caused by mono- or bisegmental pyogenic cervical discitis and intraspinal abscess without severe bone destruction. Patients were treated surgically by discectomy, decompression, and ventral spondylodesis. The disc was replaced by a PEEK cage without additional fixation. The clinical symptoms improved in all patients significantly. The authors propose that the use of PEEK cages represents a potential and safe alternative in the treatment of cervical spondylodiscitis in selected patients.
In this study, researchers from Aesculap tested alternative PEEK polymer-on-polymer articulations for cervical total disc arthroplasty with favourable biotribological properties and the benefit of radiolucency in comparison to the clinically well established metal-on-polyethylene coupling. In vitro wear simulation was performed according to ISO 18192-1:2008 (E) with the clinically introduced activ C cervical artificial disc (Aesculap AG Tuttlingen, Germany) made of UHMWPE/CoCr29Mo6 in a direct comparison to experimental disc articulations made of PEEK, CFR-PEEK and PEK. Whereas the polymer-on-polymer articulation of PEK showed no substantial benefit in comparison to polyethylene-on-cobalt-chromium and whereas natural PEEK tends towards pitting and delamination, the carbon fibre reinforced PEEK demonstrated an excellent wear behaviour with a reduction in order of a magnitude.
Strontium-containing hydroxyapatite/polyetheretherketone (Sr-HA/PEEK) composites were developed as alternative materials for load-bearing orthopaedic applications. The amount of strontium-containing hydroxyapatite (Sr-HA) incorporated into polyetheretherketone (PEEK) polymer matrix ranged from 15 to 30 vol% and the composites were successfully fabricated by compression molding technique. Strontium, in the form of strontium-containing hydroxyapatite (Sr-HA), was confirmed to enhance bioactivity in the PEEK composites.
PEEK lumbar fusion rods have recently become available for use in posterior lumbar fusion procedures. In this study, researchers from Jefferson and DePuy Spine performed biomechanical testing to evaluate PEEK rods in compressive bending and torsion. The rods were fabricated from an image-contrast grade of PEEK (6% BaSo4). Because of the flexibility of the PEEK rods, an angular displacement control variant of F1717 fatigue testing was performed in parallel with biomechanical studies in a cadaver model. PEEK rods provided comparable stability to titanium rods of equivalent diameter in cadaveric testing. Mechanical testing suggested that PEEK rods can withstand far beyond the angular displacements suggested by cadaveric testing and that of normal physiologic range of motion.
The interfacial properties of commercial poly(ether ether ketone) (PEEK) have been tailored by tethering polymeric brushes to the PEEK surface via surface-initiated atom transfer radical polymerization (SI-ATRP). The immobilization of an ATRP initiator on the PEEK surface was achieved by an unprecedented simple two-step wet chemical method. Atomic force microscopy, scanning electron microscopy, attenuated total reflection infrared spectroscopy, water contact angle measurements, and X-ray photoelectron spectroscopy ascertained the successful grafting of these polymer brushes at the PEEK surface. These brush-modified PEEK surfaces exhibited fully the physiochemical properties of the respective polymer brush: the surface with polyMPS brush showed selective staining by electrostatic interaction, while the polyMeOEGMA-modified surface was biorepellent.
At the end of 2009, ASTM published the reflectance-FTIR method for evaluating crystallinity in PEEK. The standard is designated as "F2778-09 Standard Test Method for Measurement of Percent Crystallinity of Polyetheretherketone (PEEK) Polymers by Means of Specular Reflectance Fourier Transform Infrared Spectroscopy (R-FTIR)." The test method task force for PEEK is now concentrating on expanding the small punch test standard to include PEEK biomaterials.
The seven following papers related to medical grade PEEK were presented at the 2009 meeting for the Orthopedic Research Society:
Validation of Crystallinity Measurements of Medical Grade PEEK Using Specular Reflectance FTIR-microscopy, by D. Jaekel et al.
Notched Tensile Fatigue Behavior of PEEK Under Physiologic Environmental Conditions, by Sobieraj et al.
Effects of Low Intensity Pulsed-Ultrasound (LIPUS) on the Mechanical and Thermal Properties of Polyether Ether Ketone (PEEK) and Carbon Reinforced PEEK, by Fitch et al.
Improving Human Primary Osteoblast Cytocompatibility to PEEK by Plasma Surface Modification, by Poulsson et al.
In vitro study of improving bioactivity of Polyetheretherketone (PEEK) by Plasma Immersion Ion Implantation, by Lui et al.
CaP coating on PEEK Varies upon Processing Conditions, by Bureau et al.
Comparison of Osseointegration between Dense CaO-SiO2-P2O5-B2O3 Glass-ceramics (BGS-7), Hydroxyapatite, Titanium Alloy and PEEK using Rabbit Model, by Lee et al.
To view the submitted 1-page abstracts, which are available on the ORS website, click on the links above.