Aim. To make an inoculum for induction of Implant-Associated Osteomyelitis (IAO) in pigs based on bacterial aggregates resembling those found on the human skin, i.e. aggregates of 5–15 µm with low metabolic activity. The aggregates were evaluated and compared to a standard planktonic bacterial inoculum. Method. The porcine Staphylococcus aureus strain S54F9 was cultured in Tryptone Soya Broth for seven days. Subsequently, the culture was filtered through cell strainers with pore sizes of 15 µm and 5 µm, respectively. The fraction of 5–15 µm aggregates in the top of the 5 µm filter was collected as the aggregate-inoculum. The separation of aggregates into different size fractions was evaluated by light microscopy. The metabolism of the aggregate-inoculum and a standard overnight planktonic inoculum was evaluated with isothermal microcalorimetry. In total, six female
Articular cartilage repair remains a challenge in orthopedic surgery, as none of the current clinical therapies can regenerate the functional hyaline cartilage tissue. In this study, we proposed a one-step surgery strategy that uses autologous bone marrow mesenchymal stem cells (MSCs) embedded in type II collagen (Col-II) gels to repair the full thickness chondral defects in
Long-term regeneration of cartilage defects treated with tissue engineering constructs often fails because of insufficient integration with the host tissue. We hypothesize that construct integration will be improved when implants actively interact with and integrate into the subchondral bone. Growth and Differentiation Factor 5 (GDF-5) is known to support maturation of chondrocytes and to enhance chondrogenic differentiation and hypertrophy of mesenchymal stromal cells (MSC). Therefore, we investigated whether GDF-5 is capable to stimulate endochondral ossification of MSC in vitro and in vivo and would, thus, be a promising candidate for augmenting fibrin glue in order to support integration of tissue engineering constructs into the subchondral bone plate. To evaluate the adhesive strength of fibrin glue versus BioGlue. ®. , a commercially available glue used in vascular surgery, an ex vivo cadaver study was performed and adhesion strength was measured via pull-out testing. MSC were suspended in fibrin glue and cultivated in chondrogenic medium with and without 150 ng/mL GDF-5. After 4 weeks, the formed cartilage was evaluated and half of the constructs were implanted subcutaneously into immunodeficient mice. Endochondral ossification was evaluated after 2 and 4 weeks histologically and by microCT analysis. BioGlue. ®. and GDF-5-augmented fibrin glue were tested for 4 weeks in a
Summary Statement. A porcine model using Yucatan
We evaluated the efficacy of Cite this article:
Background and aim: Mesenchymal stem cells (MSCs) are multipotent cells capable of differentiation into osteogenic and chondrogenic pathways. MSCs are among the key repair cells in fracture healing and implant osseointegration. They are also an attractive tool of cell therapy in reconstruction procedures of bone. Minipigs are a large-animal model recommended for preclinical studies of orthopaedic bone implants. Minipigs are claimed to have bone physiology close to humans, but their MSC characteristics are poorly defined. The aim of this study was to isolate and characterize
Mesenchymal stem cells (MSC) are promising for the treatment of articular cartilage defects; however, common protocols for in vitro chondrogenesis induce typical features of hypertrophic chondrocytes reminiscent of endochondral bone formation. This may implicate a risk for graft stability. We here analysed the early healing response in experimental full-thickness cartilage defects, asking whether and how MSC can differentiate to chondrocytes in an orthotopic environment. Cartilage defects in knees of
This work was aimed at study the role of paraspinal muscles on spinal tensegrity. Four different models of spinal tensegrity breakage with and without injury of the posterior spinal muscle were investigated. Fifteen
Purpose of the study: In the growing pig, we have been able to achieve localized control of vertebral body growth by selective destruction ofhte physis using the thermal effect of a laser probe (first part of the study). The purpose of the second part of the study was to evaluate the mechanical effects in terms of 1) intersomatic disc mobility, and 2) bony resistance of the vertebral body and risk of fracture. Material and methods: Thoracotomy was performed on two Yucatan micropigs (group A); a 510 nm 30W diode laser delivered heat applied to nine vertebral bodies. Four months later, the micropigs were sacrificed. Two normal micropigs (group B) served as controls. The specimens were dissected to the intersomatic disc-ligament complex. Three-level vertebral assemblies were thus obtained for mobility tests (flexion-extension, lateral inclination, right-left rotation). Destruction tests were pursued to fracture. Tests were performed with a Zebris 3D motion analyzer. Computed tomography images and histological findings were also assessed. Results: Motion: In group A, when the discal space appeared normal on the specimen, no difference was noted in motion in comparison with group B. Conversely, when imaging demonstrated discal injury, joint stiffness was noted. The destruction tests showed that in group A specimens the fracture did not occur at the zone of lytic bone destruction caused by the heat delivery. Fractures observed were similar in the two groups, including epiphyseal detachements and sagittal fractures of the vertebral bodies. Discussion: Applying laser-delivered heat to the vertebrae in micropigs enabled partial destruction of the physis without injuring the intervertebral disc. Heat delivery induced a modification in vertebral growth. When imaging showed an intact neighboring intervertebral disc, mechanical tests showed normal mobility and resistance. Bone resistance was not diminished. This result is important to consider for the treatment of vertebral osteoid osteomas with laser. Conclusion: Laser application to vertebral bone is a reproducible method which can stop growth of the
Although osteochondral defects (OCD) following trauma, sport or degenerative diseases occur frequently, healing remains an unresolved clinical problem. These defects seem to appear more often in convex surfaces than in concave ones. In vivo studies have demonstrated the influence of mechanical conditions on osteochondral repair[. 1. ]. However, the influence of the local joint curvature on the mechanical environment as well as the effect of defect fillings on healing remained unknown. We hypothesize that healing of OCD is strongly affected by the local mechanical environment generated after variations in the joint geometry specifically on concave and convex joint surfaces. To study spontaneous repair, OCD (mm, 1.5mm depth) in 18
This study evaluated the effect of a collagen type I /hyaluronate (c/h) implant combined with recombinant human growth and differentiation factor-5 (rhGDF-5) in osteochondral cartilage defects of Göttinger
Introduction: There is a need for new non-invasive, predictable and quantifiable techniques to assess the process of fracture healing and remodelling in bone. There are several methods to monitor the bone healing in-vivo. But these methods either fail as quantitative predictors of the healing process (X-ray) or exhibit complicated and expensive measurement principles. Some known in-vivo stiffness measurement methods have several disadvantages including the risk of bone malalignment. Therefore we compared ex-vivo torsional strength of bone with in-vivo torsional stiffness under minimal load in two animal model of distraction osteogenesis. Additionally the device was tested in an ex-vivo model. Methods: An external fixator was combined with a rotating double half-ring. The measurement device was fixed to the half-ring during measurements. It was equipped with a linear variable differential transducer, a load cell, and a stepper motor. During measurements the two parts of the half-ring were rotated against each other and the load and displacement were recorded. The slope coefficient after performing a linear regression between data points of moment and displacement curve was defined as stiffness. Afterwards all models were tested in a material testing system as gold standard. This was tested in an in-vivo animal study of tibial distraction (minipigs time of consolidation 10 days/sheeps time of consolidation 50 days). Results: Between in-vivo initial torsional stiffness and torsional strength in
Anatomisches Institut der Georg-August-Universität Göttingen, Germany. Biomedical Research Centre, Dept. of Orthopaedic Surgery, Academic Hospital, Pretoria, South Africa. To date, no animal model for disc degeneration has gained much acceptance, mostly due to the fact that most animals are quadrupeds and thus lack basic biomechanical characteristics of human spines. An adequate model would be of invaluable interest for degeneration related research. In a standardized series of animal experiments in 18 adult Minipigs and 20 adult Cercopithecus aethiops monkeys all animals obtained nucleotomy in one lumbar FSU from a ret-roperitoneal approach and were sacrificed at last 24 weeks afterwards. The Minipigs were x-rayed at time of sacrifice, the monkeys prior to operation and at termination of the experiment. Vice versa, the Minipigs obtained intradiscal pressure recordings at these occasions. The