PEEK biomaterials in trauma, orthopedic, and spinal implants

Abstract

Since the 1980s, polyaryletherketones (PAEKs) have been increasingly employed as biomaterials for trauma, orthopedic, and spinal implants. We have synthesized the extensive polymer science literature as it relates to structure, mechanical properties, and chemical resistance of PAEK biomaterials. With this foundation, one can more readily appreciate why this family of polymers will be inherently strong, inert, and biocompatible. Due to its relative inertness, PEEK biomaterials are an attractive platform upon which to develop novel bioactive materials, and some steps have already been taken in that direction, with the blending of HA and TCP into sintered PEEK. However, to date, blended HA-PEEK composites have involved a trade-off in mechanical properties in exchange for their increased bioactivity. PEEK has had the greatest clinical impact in the field of spine implant design, and PEEK is now broadly accepted as a radiolucent alternative to metallic biomaterials in the spine community. For mature fields, such as total joint replacements and fracture fixation implants, radiolucency is an attractive but not necessarily critical material feature.

Do Surface Porosity and Pore Size Influence Mechanical Properties and Cellular Response to PEEK?

“…Interest in improving PEEK's osseointegration has accelerated in recent years after numerous reports have described its inability in smooth form to facilitate bone apposition [9,23,25,34,51]. Reasons why this interest persists (as opposed to abandoning PEEK altogether) are often attributed to the other qualities of PEEK that make it favorable in orthopaedic and spinal applications, mainly its radiolucency, MRI compatibility, high strength, and fatigue resistance.…”

“…Polyetheretherketone (PEEK) is a polymer widely used in orthopaedic and spinal applications such as soft tissue repair and spinal fusion devices as a result of its high strength, fatigue resistance, radiolucency, and favorable biocompatibility in osseous environments [25,38,45,47,50]. However, attributable in part to PEEK's relatively inert and hydrophobic surface, recent evidence has demonstrated that smooth PEEK can exhibit poor osseointegration [9,25] and fibrous capsule formation around the implant [23,34].…”

“…However, attributable in part to PEEK's relatively inert and hydrophobic surface, recent evidence has demonstrated that smooth PEEK can exhibit poor osseointegration [9,25] and fibrous capsule formation around the implant [23,34]. Lack of bone-implant contact can induce micromotion and inflammation that leads to fibrous layer thickening, osteolysis, and implant loosening [2,13,29,37,48].…”

Effect of different surface pre-treatments and luting materials on shear bond strength to PEEK

“…The bisphenolate salt is formed in situ from bisphenol and either added sodium or added alkali metal carbonate or hydroxide, by the Williamson ether synthesis. PEEK is a semicrystalline thermoplastic with good mechanical properties [1]. The chemical structure of polyaromatic ketones provides stability at high temperatures (exceeding 300 °C), resistance to chemical and radiation damage, compatibility with many reinforcing agents (such as glass and carbon fibers), and greater strength (on a per mass basis) than many metals, making it highly attractive in industrial applications, such as aircraft and turbine blades, for example [2,3].…”

“…The chemical structure of polyaromatic ketones provides stability at high temperatures (exceeding 300 °C), resistance to chemical and radiation damage, compatibility with many reinforcing agents (such as glass and carbon fibers), and greater strength (on a per mass basis) than many metals, making it highly attractive in industrial applications, such as aircraft and turbine blades, for example [2,3]. PEEK is also considered an advanced biomaterial used in medical implants, often reinforced by biocompatible fibres such as carbon [1]. In dentistry, this material is mainly used as a plastic temporary abutment for implants in the fabrication of temporary crowns [4].…”