Chapter Modern Orthopaedic Implant Coatings — Their Pro’s, Con’s and Evaluation Methods

Environmental monitorin

The Longitudinal Assessment of Osteomyelitis Development by Molecular Imaging in a Rabbit Model

Introduction. Osteomyelitis is a severe orthopaedic complication which is difficult to diagnose and treat. Previous experimental studies mainly focussed on evaluating osteomyelitis in the presence of an implant or used a sclerosing agent to promote infection onset. In contrast, we focused on the longitudinal assessment of a nonimplant related osteomyelitis. Methods. An intramedullary tibial infection with S. aureus was established in NZW rabbits. Clinical and haematological infection status was evaluated weekly, combined with X-ray radiographs, biweekly injections of calcium binding fluorophores, and postmortem micro-CT. The development of the infection was assessed by micro-PET at consecutive time points using 18F-FDG as an infection tracer. Results. The intramedullary contamination of the rabbit tibia resulted in an osteomyelitis. Haematological parameters confirmed infection in mainly the first postoperative weeks (CRP at the first 5 postoperative weeks, leucocyte differentiation at the second and sixth postoperative weeks, and ESR on the second postoperative week only), while micro-PET was able to detect the infection from the first post-operative week onward until the end of the study. Conclusions. This study shows that osteomyelitis in the rabbit can be induced without use of an implant or sclerosing agent. The sequential follow-up indicates that the diagnostic value of each infection parameter is time point dependant. Furthermore, from all parameters used, the diagnostic value of  18F-FDG micro-PET is the most versatile to assess the presence of an orthopaedic infection in this model

Chapter Modern Orthopaedic Implant Coatings — Their Pro’s, Con’s and Evaluation Methods

Environmental monitorin

A rabbit osteomyelitis model for the longitudinal assessment of early post-operative implant infections

BACKGROUND: Implant infection is one of the most severe complications within the field of orthopaedic surgery, associated with an enormous burden for the healthcare system. During the last decades, attempts have been made to lower the incidence of implant-related infections. In the case of cemented prostheses, the use of antibiotic-containing bone cement can be effective. However, in the case of non-cemented prostheses, osteosynthesis and spinal surgery, local antibacterial prophylaxis is not a standard procedure. For the development of implant coatings with antibacterial properties, there is a need for a reliable animal model to evaluate the preventive capacity of such coatings during a specific period of time. Existing animal models generally present a limited follow-up, with a limited number of outcome parameters and relatively large animal numbers in multiple groups. METHODS: To represent an early post-operative implant infection, we established an acute tibial intramedullary nail infection model in rabbits by contamination of the tibial nail with 3.8 × 10(5) colony forming units of Staphylococcus aureus. Clinical, haematological and radiological parameters for infection were weekly assessed during a 6-week follow-up with post-mortem bacteriological and histological analyses. RESULTS: S. aureus implant infection was confirmed by the above parameters. A saline control group did not develop osteomyelitis. By combining the clinical, haematological, radiological, bacteriological and histological data collected during the experimental follow-up, we were able to differentiate between the control and the infected condition and assess the severity of the infection at sequential timepoints in a parameter-dependent fashion. CONCLUSION: We herein present an acute early post-operative rabbit implant infection model which, in contrast to previously published models, combines improved in-time insight into the development of an implant osteomyelitis with a relatively low amount of animals

The histological and histomorphometric changes in the mandible after radiotherapy:An animal model

Purpose: Approximately 5% of irradiated head and neck cancer patients develop osteoradionecrosis of the mandible. The current non-surgical treatment options for osteoradionecrosis have limited effects and are based on a small number of studies. Therefore, we aimed to enhance the understanding of the pathophysiology of osteoradionecrosis by investigating changes induced by external irradiation in minipigs.Methods: Sixteen Gottingen mini-pigs were divided into four groups for the application in two fractions with total equivalent radiation dosages of 25, 50, 70 Gray, and one group served as control. Thirteen weeks after irradiation, the left lateral teeth the mandible were removed and implants were placed. The pigs were sacrificed twenty-six weeks after irradiation, and the bone samples were stained with Masson's trichrome.Results: The amount of fibrosis, resorption lacunae, necrosis, and the woven/lamellar bone ratios were increased after higher radiation dosages. The diameter of the lumen of the inferior alveolar artery was reduced depending on the irradiation dosages. The rate of bone remodeling decreased after irradiation.Conclusion: Both surgery and increasing irradiation dosages cause architectural bone changes and damage the vascularization. This might result in a chronic hypoxic state of the mandibular bone. In general, the bone formation rate was markedly decreased after radiotherapy. (C) 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.</p

Characterization of an Ovine Bilateral Critical Sized Bone Defect Iliac Wing Model to Examine Treatment Modalities Based on Bone Tissue Engineering

Critical sized bone defect (CSBD) animal models are used to evaluate and confirm efficacy and potency of new treatment modalities based on bone tissue engineering before the latter can be applied in clinical practice. In this study, a bilateral CSBD model in the iliac wings of sheep is described in detail. To demonstrate that this is a large animal CSBD model in sheep, bone healing within the defect left empty (negative control) or filled with autologous corticocancellous bone graft (clinical gold standard, positive control) was assessed using micro-CT, histology, histomorphometric, and fluorochrome analysis. After three months, new bone into the defect site was formed across the whole defect in the positive controls but limited to the edge of the defects in the negative controls. Bone volume in the positive controls was statistically higher than in the negative controls, with the latter having less than 10% new bone growth. There were no intraoperative or postoperative complications. The model described here represents a reliable and reproducible bilateral CSBD in sheep with low morbidity that can be used for in vivo evaluation of new treatment modalities based on bone tissue engineering

Detektion von Apnoeereignissen aus Schnarchsignalen

Zur ambulanten Differenzierung zwischen primärem Schnarchen und obstruktiver Schlafapnoe wird eine kostengünstige und einfach durchführbare Diagnostik benötigt. Eine Quantifizierung der Schnarchlautstärke ist bisher nicht zufriedenstellend möglich, führt jedoch typischerweise den Patienten zum HNO-Arzt. Das Ziel dieser Studie war es, anhand von während des Schlafes aufgezeichneten Atemgeräuschen eine Software zu entwickeln, die Schnarchgeräusche quantifiziert und Atempausen detektiert.Auf der Basis von 89 Ganz-Nacht-Datensätzen von 49 Personen wurde ein Algorithmus entwickelt, der das gesamte Audiosignal mit speziellen Filtersystemen nach charakteristischen Atemgeräuschen durchsucht. Folgt auf eine Geräuschpause von mindestens 10 sec Länge ein typisches Öffnungsgeräusch, so wird diese Stelle als Apnoe-ähnliches Ereignis erkannt. Zur Ermittlung von Sensitivität und Spezifität der Software wurden die Ergebnisse dann mit den in der simultanen Polysomnographie gefundenen Atempausen verglichen. Das Ausmaß der Schnarchgeräusche wurde bezüglich ihrer Intensität und Häufigkeit quantifiziert.Zur Erzielung einer optimalen Apnoeerkennung waren Bandpassfilter und adaptive Schwellenwertbestimmung erforderlich. Bei einem Filterwert von 11 Sekunden wurde eine Sensitivität von 81,5% und eine Spezifität von 48,5% erreicht. Vereinfachte Hochpassfilter ergaben eine deutlich schlechtere Genauigkeit. Für die Beurteilung des Schnarchens wurde ein Index aus mittlerer Intensität und Schnarchhäufigkeit errechnet.Die Analyse von Atemgeräuschen im Schlaf kann erfolgreich zum Apnoescreening und zur Quantifizierung der Schnarchlautstärke genutzt werden. Weitere Modifikationen sind erforderlich, um die Genauigkeit des Systems noch zu verbessern.Supported by: teilweise unterstützt durch IFU GmbH, Lichtena