Project: PEEK based spinal implants with improved osteoconductivity and decreased infection risks

STATE-OF-THE-ART - PEEK AS IMPLANT MATERIAL:_x000D_Polyether etherketone (PEEK) is a semi-crystalline thermoplastic, exhibiting outstanding mechanical and chemical properties and being approved as a medical grade material by the U.S. FDA in the late 1990s. It is a generally accepted substitute for metallic implant materials because of its appropriate biocompatibility and extremely low elastic modulus (3-4 GPa), which reduces the extent of stress shielding that is often observed in titanium-based metallic implants. Additionally, PEEK is X-ray translucent enabling the medical imaging of surrounding tissue (magnetic resonance, computer tomography). Reasonably, PEEK is widely used for orthopedic implants._x000D__x000D_PROBLEMS WITH PEEK IMPLANTS and PROPOSED SOLUTIONS ON THE MARKET:_x000D_Despite its good mechanical properties, the adhesion of PEEK implants to bone tissue proceeds slowly because of the relatively low osteoconductivity of PEEK: After surgical intervention, the required time towards a strong bone-implant bond is much longer than for e.g. titanium implants, which finally extends the rehabilitation of the patient. Osteoconductivity is strongly affected by the surface characteristics, including surface roughness, wettability, and chemical composition. Therefore, considerable efforts have recently focused on modifying the surface of the PEEK implants to increase especially the osteoconductivity. Favorable surface modifications of the PEEK implant are possible by the introduction of bioactive coating materials using various physical and chemical methods, including plasma deposition, plasma spray deposition, and in vitro precipitation._x000D__x000D_Besides titanium, bioceramics like hydroxyapatite, calcium phosphates, bioglass, etc. with higher bioactivity were coated on PEEK and studied scientifically and technologically. CO disadvantage of these ceramic materials is their low ductility: Ductility and local plastic deformation on the micron scale prevents loss of bone-implant bonding by coating delamination from the implant surface. Generally, this problem is of higher importance for materials with lower elastic modulus: Consequently, polymers like PEEK struggle with adhesion problems of deposited ceramic coatings. In order to improve the bioactivity of titanium, one direction is the alloying or doping with bioresorbable magnesium, improving osteoblast cell adhesion, profileration, differentation and, thus, the adhesion strength implant-bone._x000D__x000D_In addition to high (and quickly establishing) bonding between bone and implant, suppressing bacterial infection at the implant site is an extremely high surgical request: Infection causes not only serious pain and suffering to patients but also increases medical costs. For spine and intervertebral disc implants the effects of infection can be much worse due to risks for the patient by nerve damage resulting in paralysis. The CO problem of nosocomial multiresistant bacteria like Staphyloccocus aureus (MRSA) and epidermidis is connected to biofilm formation, which efficiently protects against infiltration of pharmaceutical antibiotic drugs. In such case, a fast revision surgery for exchange of the implant is mandatory, because osseointegration is stopped by bacterial endotoxins. Statistical numbers reveal 8.4% infections for hip implants in 2005 with statistical extrapolation to 47.5% in 2030 in US. _x000D__x000D_GOAL OF THE PROJECT:_x000D_Consequently, strategies for anti-bacterial equipped implants against multiresistant bacteria are mandatory in future to reduce the risk of nosocomial infections. Goal of the proposed project is, thus, combing anti-bacterial behavior and improved osseointegration for translucent PEEK implants. This is planned by the consortium lead by DOPA ILAC SAN. TIC. LTD. STI. (DOPA), one of the most prominent, biomaterial R&D performing and driven implant manufacturer in Turkey, who plans to develop injection molding as a new, efficient manufacturing technology for implants. Ps is JOANNEUM RESEARCH Forschungsges.m.b.H. (JR), specialized on applied R&D and job-lot coating in the biomedical coating field (especially for polymers) in Austria. The UNIVERSITY OF KOCAELI (Turkey) is a subcontractor of DOPA and will perform material and biomaterial research and characterization._x000D__x000D_Based on medical and surgical requirements, the release of antibacterial agent, like silver, must be high immediately after implantation ("burst release"), set to lower values for the following week(s) and should finally stop after depletion of the antibacterial reservoir to prevent silver agglomeration in specific human regions (e.g. kidney). Such a concept, based on gradient coatings of biocompatible titanium, bioactive magnesium and antibacterial silver, is planned to be applied by DOPA on its future, injection molded manufactured intervertebral disc implant system (market introduction planned for 2016) and is aimed to be developed for industrial batch coating at JR in the proposed project.

Acronym Implants4Spine (Reference Number: 7691)
Duration 01/04/2013 - 30/09/2015
Project Topic The planned project targets on development of injection molding manufacturing and innovative coatings for vacuum coating deposition on PEEK intervertebral disc implants for faster bone growth and strong bone-anchoring of the implant (= faster healing) without risk of infection by bacteria.
Project Results
(after finalisation)
Aim and CO result of the project are novel spinal implants (artificial vertebral discs, manufactured from PEEK by injection moulding and coating by PVD methods with osteoconductive and antibacterical thin films)
Network Eurostars
Call Eurostars Cut-Off 9

Project partner

Number Name Role Country
2 DOPA ILAC SAN. TIC. LTD. STI. Coordinator Türkiye
2 JOANNEUM RESEARCH Forschungsgesellschaft mbH, Institute for Surface Technologies and Photonics, Research Area: Functional Surfaces Partner Austria