Hydroxyapatite Nanocoatings for PEEK (Polyether Ether Ketone) Medical Implants

By AZoNano.com Staff Writers

Topics Covered

Introduction
Coating of PEEK Implants with HAnano Surface
Adherence to PEEK Implant
Faster Osseointegration
Osseointegration of HA Coated PEEK implant
Conclusion
About Promimic AB

Introduction

During the past few decades, polymers are increasingly being used as substitutes to standard implant materials used in a variety of applications. PEEK is one such polymer that has high wear resistance, good biocompability and excellent mechanical properties. However, this material is biologically and chemically inert, which may affect its integration into the body. Due to the hydrophobic nature of the polymer it is very difficult for bone cells to attach on the surface.

The HAnano Surface is a super-thin implant coating, measuring only 20 nm, consisting of hydroxyapatite (HA), the main constituent in human bone. It can be applied to any implant material, including PEEK, because of the novel wet chemical coating technology and improves the osseointegrative properties of the implant significantly.

Figure 1. SEM picture of implant surface

Coating of PEEK Implants with HAnano Surface

When PEEK implants are coated with HAnano Surface, a material is produced whose chemical and mechanical properties has resemblance to bone. The surface can even be utilized to coat micro porous PEEK without actually clogging the pores, as depicted in the figures below.

Figure 2. Coating micro porous PEEK with HAnano Surface

Additionally, when HAnano Surface is used to coat PEEK implants the surface energy increases significantly. The material’s wettability is transformed from hydrophobic to hydrophilicdisplaying a decrease in contact angle from 90º to 30º. Such increased wettability improves cell attachment and protein adsorption. The HAnano Surface’s nano particles imitate the natural bone minerals and creates a known surface for the bone cells.

Adherence to PEEK Implant

When HAnano Surface is applied, an even layer of nano-sized hydroxyapatite crystals covers the entire surface of the implant down to the smallest pore. The novel wet chemical coating technology and nano structure produce a perfect adherence between the nano crystals of the HAnano Surface and the PEEK substrate.

Faster Osseointegration

Figure 3. Removal Torque in vivo study

The use of HAnano Surface is proven in more than 10 preclinical in vivo studies. The collective results demonstrate that the HAnano Surface accelerates and enhances integration between bone and implant. A removal torque study conducted in rabbit demonstrated an average of 62% higher removal torque for PEEK coated with HAnano Surface, as compared to unmodified PEEK. Since HA has a thin layer, it considerably enhances the growth of bone cells on the surface, leading to a faster osseointegration and stronger anchoring of the implant.

Osseointegration of HA Coated PEEK implant

Improved biological response is observed when HAnano Surface is applied to PEEK implants. Bone cells are attracted to the implant’s surface through the nano-sized hydroxyapatite particles, significantly increasing the contact between implant and bone.

The figures shown below illustrate two histological sections of bone integration on PEEK taken from a pre-clinical in vivo study conducted in rabbit over a period of six weeks. The results demonstrate a clear difference between the coated implant and pure PEEK, as they demonstrate an improved integration for the HAnano Surface coated PEEK implant.

Figure 4. Histological sections from an in-vivo study of osseointegration of coated PEEK implants.

Conclusion

From the above observations, it is evident that applying HAnano Surface on PEEK implants changes the polymer surface from bioinert to osteoconductive, producing a material with similar chemical and mechanical properties like bone. Furthermore, the presence of the HAnano Surface  creates a hydrophilic implant surface and does not impact the material’s strength. Results from pre-clinical in vivo studies clearly show that for HAnano Surface coated PEEK an increased anchoring strength, and accelerated osseointegration could be observed when compared to non-modified PEEK.

About Promimic AB

Promimic is a biomaterial company founded in 2004 as a spin-off from research performed at Chalmers University of Technology in Gothenburg, Sweden. The company develops and markets a new generation of implant surface modifications and synthetic bone based on a patented method for production of nano sized hydroxyapatite. Promimic has an innovative and experienced organization that continuously is working on new ways to improve surface modification and coating of new materials.

  • HAnano Surface is a unique implant surface which dramatically accelerate osseointegration. The surface can be applied onto various types of materials - including metals, ceramics and polymers - regardless of its dimensions and structure. The HAnano Surface has received 510(k) approval by the FDA (American Food and Drug Administration), which applies to the area of dental implants.
  • HAnano Bone is a new generation of synthetic bone. The unique composition of HAnano Bone allows it to be mouldable over extended periods of time.

This information has been sourced, reviewed and adapted from materials provided by Promimic AB.

For more information on this source, please visit Promimic AB.

 

Date Added: Aug 29, 2013 | Updated: Sep 5, 2013
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