Nano‐hydroxyapatite‐coated PEEK implants: A pilot study in rabbit bone

Abstract

Osseointegration of surface-modified polyetheretherketone (PEEK) implants was studied in vivo. A total of 18 cylinder-shaped PEEK implants were inserted in the femurs of nine New Zealand rabbits; half were coated with nanocrystalline hydroxyapatite (nanoHA) and half were uncoated controls. Healing time was 6 weeks. Samples were retrieved with the implant and surrounding tissue, processed to cut and ground sections, and analyzed histomorphometrically. The implant surfaces were analyzed with optical interferometry, scanning electron microscopy (SEM), atomic force microscopy, and X-ray photoelectron spectroscopy (XPS). NanoHA-coated PEEK surfaces had lower height deviation (Sa) than controls [mean ± SD: 0.41 μm (± 0.14) vs. 0.96 μm (± 0.28)]. SEM images showed the nanoHA crystals as a thin layer on the polymer surface. XPS analysis of the coated implants showed a Ca/P ratio of 1.67. Histomorphometry indicated that the nanoHA-coated implants had more bone-to-implant contact [16% (± 4.7) vs. 13% (± 9.3)] and more bone area [52% (± 9.5) vs. 45% (± 11.9)]. We found no difference between smooth nanoHA-coated cylinder-shaped PEEK implants and uncoated controls. However, higher mean bone-to-implant contact indicated better osseointegration in the coated implants than in the uncoated controls. The large number of lost implants was interpreted as a lack of primary stability due to implant design.

Fortifying the Bone-Implant Interface Part 2: An In Vivo Evaluation of 3D-Printed and TPS-Coated Triangular Implants

“…These AM implants likewise demonstrated substantial bone ongrowth and ingrowth to their porous surfaces, with additional bone through growth in the cores. Although similar HA coatings have previously demonstrated a beneficial effect on non-porous titanium surfaces or inert structures, such as PEEK, 26,27 the current study showed that the dip, spin, heat treated nanocrystalline HA coating did not further enhance results compared to uncoated AM implants. The addition of autograft, on the other hand, resulted in significantly increased bone ingrowth and through growth within the AM implant, potentially further promoting osteointegration.…”

“…For AM+HA implants, a ~20nm layer of HA was applied to implant surfaces using a dip-coating precipitate technique as previously described. 26,27 AM+Auto implants are described in the Animal Model section below. All implants were gamma-sterilized prior to use.…”

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

“…A recently published study, using an identical HA coating as in the present study, revealed a higher mean bone-to-implant contact for HA, indicating a higher level of osseointegration. 31 Conversely, due to an unfavorable implant design, a large number of implants were lost due to a lack of primary stability. The design of the implant in the present study has taken into account the result of the previous study in order to achieve better primary stability.…”

“…However, there were large numbers of lost implants due to loss of primary stability since the implants lacked threads. 31 Therefore, the implant was redesigned and now possesses wide and shallow threads for primary stability to allow initial osseointegration. The implant was also designed to be fully submerged into the bone to minimize external loading during healing.…”

Functionalization of polyethetherketone for application in dentistry and orthopedics

“…Thus, the liquid coating material is evenly spread on the substrate, while excess material is spun down, so that the film thickness can be controlled by speed and process time. This method has been used for coating of PEEK with HA and yielded promising results [46]. (iv) Aerosol-coating is a powder spray method, where the substrate to be coated is exposed to an aerosol containing fine particles of the coating material.…”