Nanosized Hydroxyapatite Coating on PEEK Implants Enhances Early Bone Formation: A Histological and Three-Dimensional Investigation in Rabbit Bone.
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ABSTRACT:
SUBMITTER: Johansson P
PROVIDER: S-EPMC5455651 | biostudies-other | 2015 Jun
REPOSITORIES: biostudies-other
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Project description:The aim of this study was to evaluate the osseointegration of titanium implants (Ti-6Al-4V, noted here TA6V) and poly(etheretherketone) PEEK implants induced by a BMP-2-delivering surface coating made of polyelectrolyte multilayer films. The in vitro bioactivity of the polyelectrolyte film-coated implants was assessed using the alkaline phosphatase assay. BMP-2-coated TA6V and PEEK implants with a total dose of 9.3?g of BMP-2 were inserted into the femoral condyles of New Zealand white rabbits and compared to uncoated implants. Rabbits were sacrificed 4 and 8weeks after implantation. Histomorphometric analyses on TA6V and PEEK implants and microcomputed tomography on PEEK implants revealed that the bone-to-implant contact and bone area around the implants were significantly lower for the BMP-2-coated implants than for the bare implants. This was confirmed by scanning electron microscopy imaging. This difference was more pronounced at 4weeks in comparison to the 8-week time point. However, bone growth inside the hexagonal upper hollow cavity of the screws was higher in the case of the BMP-2 coated implants. Overall, this study shows that a high dose of BMP-2 leads to localized and temporary bone impairment, and that the dose of BMP-2 delivered at the surface of an implant needs to be carefully optimized.The presentation of growth factors from material surfaces currently presents significant challenges in academia, clinics and industry. Applying osteoinductive factors to different types of implants, made of metals or polymers, may improve bone repair in difficult situations. Here, we show the effects of an osteoinductive coating made of polyelectrolyte multilayer films on two widely used materials, titanium TA6V alloys and PEEK implants, which were implanted in the rabbit femoral condyle. We show that a too high dose of BMP-2 delivered from the screw surface has a negative short-term effect on bone regeneration in close vicinity of the screw surface. In contrast, bone formation was increased at early times in the empty spaces around the screw. These results highlight the need for future dose-dependence studies on bone formation in response to osteoinductive coatings.
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Project description:Surface modification of orthopedic and dental implants has been demonstrated to be an effective strategy to accelerate bone healing at early implantation times. Among the different alternatives, coating implants with a layer of hydroxyapatite (HAp) is one of the most used techniques, due to its excellent biocompatibility and osteoconductive behavior. The composition and crystalline structure of HAp allow for numerous ionic substitutions that provide added value, such as antibiotic properties or osteoinduction. In this article, we will review and critically analyze the most important advances in the field of substituted hydroxyapatite coatings. In recent years substituted HAp coatings have been deposited not only on orthopedic prostheses and dental implants, but also on macroporous scaffolds, thus expanding their applications towards bone regeneration therapies. Besides, the capability of substituted HAps to immobilize proteins and growth factors by non-covalent interactions has opened new possibilities for preparing hybrid coatings that foster bone healing processes. Finally, the most important in vivo outcomes will be discussed to understand the prospects of substituted HAp coatings from a clinical point of view.
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Project description:To investigate and assess bone regeneration in sheep in combination with new implant materials classical histological staining methods as well as immunohistochemistry may provide additional information to standard radiographs or computer tomography. Available published data of bone defect regenerations in sheep often present none or sparely labeled histological images. Repeatedly, the exact location of the sample remains unclear, detail enlargements are missing and the labeling of different tissues or cells is absent. The aim of this article is to present an overview of sample preparation, staining methods and their benefits as well as a detailed histological description of bone regeneration in the sheep tibia. General histological staining methods like hematoxylin and eosin, Masson-Goldner trichrome, Movat's pentachrome and alcian blue were used to define new bone formation within a sheep tibia critical size defect containing a polycaprolactone-co-lactide (PCL) scaffold implanted for 3 months (n = 4). Special attention was drawn to describe the bone healing patterns down to cell level. Additionally one histological quantification method and immunohistochemical staining methods are described.
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Project description:A firm connection of the bone-implant-fixation system is of utmost importance for patients with cranial defects. In order to improve the connection reliability, the current research focuses on finding the optimal fixation method, as well as selection of the implant manufacturing methods and the used materials. For the latter, implementation of bioactive materials such as hydroxyapatite or other calcium phosphates has also been considered in the literature. The aim of this study was to investigate the effect of gradual osseointegration on the biomechanical performance of cranial Ti6Al4V implants with a deposited HA coating as the osseointegration agent. This effect was assessed by two different computational approaches using finite element method (FEM) modeling. The values of key input parameters necessary for FEM were obtained from experimental plasma spray deposition of HA layers onto Ti6Al4V samples. Immediately upon implantation, the HA layer at the bone-implant contact area brought only a slight decrease in the values of von Mises stress in the implant and the micro-screws when compared to a non-coated counterpart; importantly, this was without any negative trade-off in other important characteristics. The major benefit of the HA coatings was manifested upon the modeled osseointegration: the results of both approaches confirmed a significant reduction of investigated parameters such as the total implant displacements (reduced from 0.050 mm to 0.012 mm and 0.002 mm while using Approach I and II, respectively) and stresses (reduced from 52 MPa to 10 MPa and 1 MPa) in the implanted components in comparison to non-coated variant. This is a very promising result for potential use of thermally sprayed HA coatings for cranial implants.
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Project description:BACKGROUND:In cranial reconstruction, the features of artificial bone differ. Custom-made porous hydroxyapatite (HAp) implants for cranioplasty have been used all over the world because of their good cosmetic, biocompatibility, and osteoconductive properties. Surgical techniques were analyzed, and histological assessment of new bone formation in the hydroxyapatite was performed. METHODS:Over a 6-year time period, 41 patients underwent cranioplasty using a custom-made three-dimensional hybrid pore structured hydroxyapatite (3DHPoHAp) implant. The surgical techniques and histological evaluations of 3DHPoHAp in 2 cases, removed 6 months and 2.5 years after cranioplasty, are described. RESULTS:Using 3DHPoHAp, cranioplasty was successfully performed for all patients. The implant fit the bone defect exactly, and surgical manoeuvres were simple and easy. All implants were firmly fixed using a titanium plate, and postoperative infection occurred in 1 patient (2.4%). New bone formation was seen in 2 cases 6 months and 2.5 years after cranioplasty. Osteoblasts were progressing to the stoma at various depths, and bone tissue had ripened. Furthermore, lamellar structure was observed in the case at 2.5 years. CONCLUSIONS:In this study, there was a low infection rate, and new bone formation was seen in vivo after cranioplasty. This study also demonstrated that the 3DHPoHAp implant is a good candidate for cranial bone implants because its good osteoconductivity and biocompatibility.
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Project description:Synthetic osteoinductive materials that mimic the human osteogenic niche have emerged as ideal candidates to address this area of unmet clinical need. In this study, we evaluated the osteoinductive potential in a rabbit orthotopic model of a magnesium-doped hydroxyapatite/type I collagen ?(MHA/Coll) composite. The composite was fabricated to exhibit a highly fibrous structure of carbonated MHA with 70% (±2.1) porosity and a Ca/P ratio of 1.5 (±0.03) as well as a diverse range of elasticity separated to two distinct stiffness peaks of low (2.35 ?± ?1.16 ?MPa) and higher (9.52 ?± ?2.10 ?MPa) Young's Modulus. Data suggested that these specific compositional and nanomechanical material properties induced the deposition of de novo mineral phase, while modulating the expression of early and late osteogenic marker genes, in a 3D in vitro model using human bone marrow-derived mesenchymal stem cells (hBM-MSCs). When tested in the rabbit orthotopic model, MHA/Col1 scaffold induction of new trabecular bone mass was observed by DynaCT scan, only 2 weeks after implantation. Bone histomorphometry at 6 weeks revealed a significant amount of de novo bone matrix formation. qPCR demonstrated MHA/Coll scaffold full cellularization in vivo and the expression of both osteogenesis-associated genes (Spp1, Sparc, Col1a1, Runx2, Dlx5) as well as hematopoietic (Vcam1, Cd38, Sele, Kdr) and bone marrow stromal cell marker genes (Vim, Itgb1, Alcam). Altogether, these data provide ?evidence of the solid osteoinductive potential of MHA/Coll and its suitability for multiple approaches of bone regeneration.
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Project description:There is a substantial global market for orthopedic implants, but these implants still face the problem of a high failure rate in the short and long term after implantation due to the complex physiological conditions in the body. The use of multifunctional coatings on orthopedic implants has been proposed as an effective way to overcome a range of difficulties. Here, a multifunctional (TA@HA/Lys)n coating composed of tannic acid (TA), hydroxyapatite (HA), and lysozyme (Lys) was fabricated in a layer-by-layer (LBL) manner, where TA deposited onto HA firmly stuck Lys and HA together. The deposition of TA onto HA, the growth of (TA@HA/Lys)n, and multiple related biofunctionalities were thoroughly investigated. Our data demonstrated that such a hybrid coating displayed antibacterial and antioxidant effects, and also facilitated the rapid attachment of cells [both mouse embryo osteoblast precursor cells (MC3T3-E1) and dental pulp stem cells (DPSCs)] in the early stage and their proliferation over a long period. This accelerated osteogenesis in vitro and promoted bone formation in vivo. We believe that our findings and the developed strategy here could pave the way for multifunctional coatings not only on orthopedic implants, but also for additional applications in catalysts, sensors, tissue engineering, etc.
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Project description:In this paper, a series of structurally modified silicate-substituted apatite co-doped with Sr2+ and Eu3+ ions were synthesized by a microwave-assisted hydrothermal method. The concentration of Sr2+ ions was set at 2 mol% and Eu3+ ions were established in the range of 0.5-2 mol% in a molar ratio of calcium ion amount. The XRD (X-ray powder diffraction) technique and infrared (FT-IR) spectroscopy were used to characterize the obtained materials. The Kröger-Vink notation was used to explain the possible charge compensation mechanism. Moreover, the study of the spectroscopic properties (emission, emission excitation and emission kinetics) of the obtained materials as a function of optically active ions and annealing temperature was carried out. The luminescence behavior of Eu3+ ions in the apatite matrix was verified by the Judd-Ofelt (J-O) theory and discussed in detail. The temperature-dependent emission spectra were recorded for the representative materials. Furthermore, the International Commission on Illumination (CIE) chromaticity coordinates and correlated color temperature were determined by the obtained results.
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Project description:Background:The treatment of fracture- or non-union-related infections has persistently been a major challenge for both patients and treating surgeons. With rising aging of patients and increasing comorbidities, combined with the heterogeneity of germs and any number of multi-resistance against standard antibiotics, a successful treatment is increasingly difficult. One potential solution could be a custom-made individualized antibacterial coating of standard implants with a biphasic degradable biocarrier (Cerament G/V, supplied by Bonesupport AB, Lund, Sweden) that releases high doses of antibiotics around the bone-implant-interface. Here, we describe our technique of coating intramedullary nails, plates and press-fit shoulder endoprostheses which may prevent bacterial adhesion and biofilm formation. So far, there is very limited experience in individual coating of implants in hip or knee endoprostheses to prevent reoccurrence of surgical-site infection. Currently, no reports are available for coating of stems of shoulder prosthesis and nails or plates for fracture fixation. Methods:Here, we show our first experiences with a new individualized surgical technique of coating these implants with a resorbable antibiotic-loaded hydroxyapatite/calcium sulphate biocomposite to prevent biofilm formation and thereby recurrence of bone or joint infection. We describe three cases for coating of plates and nails for fracture fixation and coating of stems of a shoulder prosthesis. Results:No adverse events of the resorbable bone graft substitute were observed. In all of the cases, no recurrence of the infection was observed and osseointegration was achieved. After implant coating of the shoulder prosthesis, no radiological signs of loosening were detected. Conclusion:We present a new surgical approach of a surface coating of plates, intramedullary nails or prostheses. The osteoconductive- and anti-inflammatory effect of the gentamicin- or vancomycin-loaded hydroxyapatite/calcium sulphate bone graft substitutes shows promising results.
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Project description:Purpose:To assess the clinical efficacy of custom made PEEK patient-specific implants in treatment of orbital wall defects. Methods:Forty-five patients with unilateral post-traumatic orbital wall defects were enrolled in the study. They underwent subsequent reconstructive procedures using PEEK patient-specific implants (PSI) or pre-bent titanium plates. All the patients were examined with the standardized algorithm, including local status examination, vision assessment and computer tomography (CT) with measurements of the orbital volume. A comparative analysis of the treatment outcomes in two groups of patients (pre-bent plates/PSI) was performed. Results:The study findings show an absence of any postoperative infection, inflamation or decreased visual acuity in either group. In PSI group, diplopia after surgery was absent in 82.1% of patients versus 70.6% of controls. The mean duration of surgery was 54.25 ± 16.8 min with PSI application and 82.9 ± 10.8 min with pre-bent plates. The mean difference between the intact and damaged orbital volume was 1.9 ± 1.4 cm3 in the control group versus 0.74 ± 0.6 cm3 in PSI group (?<0.05). Conclusion:PEEK PSI demonstrated higher clinical efficacy in comparison to pre-bent plates in orbital wall reconstruction especially in restoring the volume and shape of the damaged orbit.
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