Polyetheretherketone (PEEK) has the potential to overcome some of the disadvantages of titanium interbody implants in anterior cervical and discectomy and fusion (ACDF). However, PEEK shows an inferior biological behavior regarding osseointegration and bioactivity. Therefore, the aim of the study was to create a bioactive surface coating on PEEK implants with a unique nanopore structure enabling the generation of a long-lasting interfacial composite layer between coating material and implant. Seventy-two PEEK implants—each thirty-six pure PEEK implants (PI) and thirty-six PEEK implants with a sprayed coating consisting of nanocrystalline hydroxyapatite (ncHA) embedded in a silica matrix and interfacial composite layer (SPI)—were inserted in the femoral condyles of adult rats using a split-side model. After 2, 4 and 8 weeks, the femur bones were harvested. Half of the femur bones were used in histological and histomorphometrical analyses. Additionally, pull-out tests were performed in the second half. Postoperative healing was uneventful for all animals, and no postoperative complications were observed. Considerable crestal and medullary bone remodeling could be found around all implants, with faster bone formation around the SPI and fewer regions with fibrous tissue barriers between implant and bone. Histomorphometrical analyses showed a higher bone to implant contact (BIC) in SPI after 4 and 8 weeks (p < 0.05). Pull-out tests revealed higher pull-out forces in SPI at all time points (p < 0.01). The presented findings demonstrate that a combination of a bioactive coating and the permanent chemical and structural modified interfacial composite layer can improve bone formation at the implant surface by creating a sustainable bone-implant interface. This might be a promising way to overcome the bioinert surface property of PEEK-based implants.

Currently used methods for processing allogeneic bone grafts like gamma irradiation are connected with downside of altering the mechanical properties of the graft. As an alternative, high hydrostatic pressure (HHP) leads to an effective devitalization of cells without influencing the bone matrix and its mechanical behavior. To address the clinical application, bone plates were prepared out of HHP-treated bone granules, which are conceivable for augmentations in the jaw region. In order to achieve sufficient mechanical strength, two different adhesives were tested. Mechanical characterization by three-point bending tests was performed. Furthermore, analysis regarding cytotoxicity as well as colonization experiments with mesenchymal stem cells were performed to investigate osteoconductive properties of the bone plates. While plates composed of fibrin glue showed better biocompatibility, plates prepared with Loctite® 408 showed better mechanical properties and could be incorporated in a model application. Regardless of the adhesive, bone plates induced osteogenic differentiation compared to cells cultured without bone plates. Although an adhesive combining both properties would be necessary for later clinical application, the study at hand demonstrates the possibility of producing allogeneic bone plates from HHP-treated granules, which meet the basic requirements for jaw augmentation.