Biomechanical evaluation and surface characterization of a nano-modified surface on PEEK implants: a study in the rabbit tibia

Abstract

Polyether ether ketone (PEEK) is today frequently used as a biomaterial in different medical operations due to its excellent mechanical and chemical properties. However, the untreated surface of PEEK is bioinert and hydrophobic, and it does not osseointegrate in its pure form. The aim of this study was to evaluate a unique nano-modified surface of PEEK with respect to osseointegration. Forty-eight threaded, non-cutting PEEK implants were inserted bilaterally in the tibia of 24 rabbits. Half of the implants (n=24) were coated with nanocrystalline hydroxyapatite (test) and the remaining implants (n=24) were left uncoated (control). Half of the animals (n=12) were euthanized after 3 weeks of healing and the remaining (n=12) after 12 weeks. The implant retention was measured with a removal torque apparatus. Surface analysis was performed with interferometry, scanning electron microscopy, and X-ray photon spectroscopy to relate the removal torque to the applied surface. The test implants revealed a significantly higher retention after 3 weeks ( P =0.05) and 12 weeks ( P =0.028) compared to controls. The result of the present study proves that the addition of nanocrystalline hydroxyapatite coating to PEEK surfaces significantly increases its removal torque and biocompatibility.

Nanosized Hydroxyapatite Coating on PEEK Implants Enhances Early Bone Formation: A Histological and Three-Dimensional Investigation in Rabbit Bone

“…This trend has been confirmed in several previous studies evaluating thin coating layers [24,25,26]. Our finding with regard to a stronger bone reaction to test implants is supported by our previous biomechanical study on similar test and control implants [27]. In this previous study, the removal torque for 3 weeks was 13.0 and 7.18 Ncm, and for 12 weeks, 9.75 and 5.58 Ncm, for test and control implants, respectively.…”

“…To make the surface conductive, the implants were sputtered with gold in a Jeol JFC-1100E ion sputter (JEOL Ltd., Tokyo, Japan) at 10 mA for 90 s. The nano- and microtopography was described in a previous report [27]. …”

Polyether ether ketone implants achieve increased bone fusion when coated with nano-sized hydroxyapatite: a histomorphometric study in rabbit bone

“…The increased removal torque for the HA-coated implants compared to uncoated controls is correlated to the higher BIC for test implants. 23 Another previous study by our team evaluated the same implant design and surface modification inserted in the rabbit tibia. The results revealed a significantly higher BIC and BA after 3 weeks for HA-coated implants.…”

Biomechanical, histological, and computed X‐ray tomographic analyses of hydroxyapatite coated PEEK implants in an extended healing model in rabbit

“…[26][27][28] The results were convincing and revealed a significantly higher degree of osseointegration for coated implants compared to neat PEEK. [26][27][28] The results were convincing and revealed a significantly higher degree of osseointegration for coated implants compared to neat PEEK.…”

“…10,11 PEEK is considered to be a relatively bioinert material and does not release ions, corrode or degrade in biological situations. [26][27][28] However, the increased bone formation and removal torque were most prominent for HA-PEEK after 3 weeks compared to 12 weeks. [12][13][14] Improving the bioactivity of PEEK is currently a major research topic and several methods and substances are under investigation.…”