Von Rechenberg B.,University of Zürich |
Genot O.R.,University of Zürich |
Nuss K.,University of Zürich |
Galuppo L.,University of California at Davis |
And 5 more authors.
European Journal of Pharmaceutics and Biopharmaceutics | Year: 2013
Four cement applications were tested in this investigation. Two dicalcium phosphate dihydrate (DCPD-brushite) hydraulic cements, an apatite hydraulic fiber loaded cement, and a calcium sulfate cement (Plaster of Paris) were implanted in epiphyseal and metaphyseal cylindrical bone defects in sheep. The in vivo study was performed to assess the biocompatibility and bone remodeling of four cement formulations. After time periods of 2, 4, and 6 months, the cement samples were clinically and histologically evaluated. Histomorphometrically, the amount of new bone formation, fibrous tissue, and bone marrow and the area of remaining cement were measured. In all specimens, no signs of inflammation were detectable either macroscopically or microscopically. Cements differed mainly in their resorption time. Calcium sulfate was already completely resorbed at 2 months and showed a variable amount of new bone formation and/or fibrous tissue in the original drill hole over all time periods. The two DCPD cements in contrast were degraded to a large amount at 6 months, whereas the apatite was almost unchanged over all time periods. © 2013 Elsevier B.V. All rights reserved.
Kraft M.,Synthes GmbH |
Koch D.K.,Synthes Inc. |
Bushelow M.,Synthes Inc.
Spine Journal | Year: 2012
Background context: Total disc replacement (TDR) is a relatively new reconstructive non-fusion technology for the spine that aims to overcome some of the limitations of fusion technology. The first generation artificial discs were mainly based on well-known material combinations from total hip replacement. Purpose: To evaluate the feasibility of PEEK-on-PEEK as a bearing surface material for use in cervical TDR. Study design: In vitro biotribological study including the assessment of different parameters, including the influence of radial clearance, axial load, and angular motion on the wear performance of a PEEK-on-PEEK bearing. Methods: PEEK-on-PEEK bearing couples with ball-and-socket articulation were prepared using standard production methods. Two groups of bearing couples, one with large radial clearances and the other with small radial clearances, were manufactured for testing. Wear tests were performed using a servo-hydraulic wear simulator that allowed controlled motions to be applied in three axes corresponding to flexion-extension, lateral bending, and axial rotation. In addition, a dynamic axial compressive load was applied to simulate the weight of the head. All tests were performed at 37°C (±2°C) in bovine calf serum with a 30 g/l protein concentration. In the first test series, the influence of the radial clearance on the wear behavior was evaluated using the load and motion parameters for cervical TDR as defined in the ISO standard 18192-1. Subsequent tests were performed to check if surface degradation was influenced by thermal effects. Finally, in a third series of tests, the effect of load and motion profiles on wear performance was investigated by applying increased loads and corresponding motion parameters for lumbar TDR as defined in the ISO standard 18192-1. Results: The measured wear rates for a PEEK-on-PEEK bearing under cervical test conditions were considerably larger than those of similar testing using UHMWPE-on-CoCr and seemed to depend on initial radial clearances. The PEEK bearing surfaces exhibited severe surface degradation for large and small clearances, but the group with smaller clearances seemed to have less severe damage. Thermal effects were not found to play a role in the surface degradation, as the temperature near the bearing surface was measured and found to vary only a few degrees during testing. A change of the wear test parameters to simulate lumbar loading resulted in a considerable wear rate reduction as well as in the preservation of the bearing surfaces. Conclusions: It was found that a cervical TDR using a PEEK-on-PEEK bearing may be subjected to severe long-term degradation of the bearing surfaces. In this study, the use of PEEK as an articulation material for cervical TDR was found to be sensitive to loading conditions as well as to the initial clearance of the bearing surfaces. Despite the excellent properties of PEEK as an implant material, its use for articulating surfaces for cervical TDR must be critically reviewed. © 2012 Elsevier Inc. All rights reserved.
Green J.,Synthes Inc.
Injury | Year: 2010
Excessive intramedullary pressure coincident to surgical procedures requiring entrance and surgical manipulation within the intramedullary canal is a problem that was recognized by Gerhard Küntscher, the godfather of intramedullary nailing. He expressed concern about this phenomenon in his early writings during the 1940's. Although he suggested certain technical methods to moderate the event while doing the surgical procedure he had no solution for absolutely preventing its occurrence. This became more of an issue after he introduced motorized reaming in the mid 1950's to improve the strength of intramedullary fixation. The first to demonstrate that pressure could be avoided during intramedullary surgeries were Lorenzi, Olerud and Dankwardt- Lillieström in the late 1960's. Using a method that employed suction evacuation of intramedullary content prior to reaming, and by introducing irrigation while reaming, they were able to achieve negative pressures during their intramedullary work. They proved that if an IM technique did not inject fat throughout the bone and into the organism there were significant benefits both locally and systemically. With impeccable methodology, they showed fat destroyed the vascularity of the bone and inhibited its revascularization. Systemically, its presence was associated with death and morbidity. K.M. Stürmer, using sheep in studies done in the 1980's, further validated the effectiveness of negative pressure reaming to prevent adverse effects associated with reaming. The attempt to create a device to provide these benefits clinically, however, has been challenging. The group in Muenster did work with a rinsing-suction-reamer (RSR) that showed fat introduction with reaming need not be significantly greater than when using an external fixator. In the US, the effort has focused on developing a reamer that integrated suction and irrigation into its design. This instrument has been given the acronym of RIA (reamer/irrigator/aspirator). The rationale and development of this system is detailed in this paper. Now that the intramedullary canal can be reamed using a negative pressure method this domain, as a unique source of biological material, is being increasingly investigated. The cells and tissue harvested from this space have tremendous therapeutic promise. © 2010 Elsevier Ltd. All rights reserved.
Moroni A.,University of Bologna |
Hoque M.,University of Bologna |
Waddell J.P.,St Michaels Hospital |
Russell T.A.,University of Memphis |
And 2 more authors.
Archives of Orthopaedic and Trauma Surgery | Year: 2014
Introduction: Osteoporosis-related hip fractures are associated with high mortality and costs. The optimum type of treatment for such fractures is controversial. To shed some light on this issue, the surgical treatment and management of osteoporotic hip fractures were discussed during a hip fracture surgical working group at the 2009 International Society For Fracture Repair Annual Meeting comprising leading experts in the field. Materials and methods: The working group consisted of eight orthopaedic surgeons, six industry representatives and one research scientist. Eleven participants were from Europe and four were from the USA and Canada. Two chairmen posed 12 questions relating to the surgical treatment and management of osteoporotic hip fractures. Each question was discussed and key points were noted. Results: Surgery should commence within 24-48 h but the patient should be optimized if presenting with ≥3 comorbidities. Specialized centres integrating orthopaedics, geriatricians and rheumatologists could be a solution for the lack of specialist care post-surgery. Surgical technique is important in fracture fixation, as is the implant, but there has been no improvement in implant design in the past 50 years. As a consequence, malunion has become unjustifiably accepted. Fracture healing can be accelerated using pharmaceuticals which are also important in secondary prophylaxis. All displaced femoral neck fractures in geriatric patients should be treated with hip replacement, the choice between using cemented or uncemented fixation being at the surgeon's discretion. Discussion and conclusion: This working group discussion highlighted several important issues which could be of interest to the orthopaedic community. © 2011 Springer-Verlag.
Kim J.-S.,Rush University Medical Center |
Ellman M.B.,Rush University Medical Center |
Yan D.,Rush University Medical Center |
An H.S.,Rush University Medical Center |
And 10 more authors.
Journal of Cellular Physiology | Year: 2013
The catabolic cytokine interleukin-1 (IL-1) and endotoxin lipopolysaccharide (LPS) are well-known inflammatory mediators involved in degenerative disc disease, and inhibitors of IL-1 and LPS may potentially be used to slow or prevent disc degeneration in vivo. Here, we elucidate the striking anti-catabolic and anti-inflammatory effects of bovine lactoferricin (LfcinB) in the intervertebral disc (IVD) via antagonism of both IL-1 and LPS-mediated catabolic activity using in vitro and ex vivo analyses. Specifically, we demonstrate the biological counteraction of LfcinB against IL-1 and LPS-mediated proteoglycan (PG) depletion, matrix-degrading enzyme production, and enzyme activity in long-term (alginate beads) and short-term (monolayer) culture models using bovine and human nucleus pulposus (NP) cells. LfcinB significantly attenuates the IL-1 and LPS-mediated suppression of PG production and synthesis, and thus restores PG accumulation and pericellular matrix formation. Simultaneously, LfcinB antagonizes catabolic factor mediated induction of multiple cartilage-degrading enzymes, including MMP-1, MMP-3, MMP-13, ADAMTS-4, and ADAMTS-5, in bovine NP cells at both mRNA and protein levels. LfcinB also suppresses the catabolic factor-induced stimulation of oxidative and inflammatory factors such as iNOS, IL-6, and toll-like receptor-2 (TLR-2) and TLR-4. Finally, the ability of LfcinB to antagonize IL-1 and LPS-mediated suppression of PG is upheld in an en bloc intradiscal microinjection model followed by ex vivo organ culture using both mouse and rabbit IVD tissue, suggesting a potential therapeutic benefit of LfcinB on degenerative disc disease in the future. © 2013 Wiley Periodicals, Inc.
Villasmil M.L.,The Institute of Metabolic Disorders |
Villasmil M.L.,Cato Research Ltd. |
Francisco J.,The Institute of Metabolic Disorders |
Gallo-Ebert C.,The Institute of Metabolic Disorders |
And 5 more authors.
Cell Cycle | Year: 2016
Sphingolipids are major constituents of membranes. A number of S. cerevisiae sphingolipid intermediates such as long chains sphingoid bases (LCBs) and ceramides act as signaling molecules regulating cell cycle progression, adaptability to heat stress, and survival in response to starvation. Here we show that S. cerevisiae haploid cells must synthesize ceramide in order to induce mating specific cell cycle arrest. Cells devoid of sphingolipid biosynthesis or defective in ceramide synthesis are sterile and harbor defects in pheromone-induced MAP kinase-dependent transcription. Analyses of G1/S cyclin levels indicate that mutant cells cannot reduce Cln1/2 levels in response to pheromone. FACS analysis indicates a lack of ability to arrest. The addition of LCBs to sphingolipid deficient cells restores MAP kinase-dependent transcription, reduces cyclin levels, and allows for mating, as does the addition of a cell permeable ceramide to cells blocked at ceramide synthesis. Pharmacological studies using the inositolphosphorylceramide synthase inhibitor aureobasidin A indicate that the ability to synthesize and accumulate ceramide alone is sufficient for cell cycle arrest and mating. Studies indicate that ceramide also has a role in PI(4,5)P2 polarization during mating, an event necessary for initiating cell cycle arrest and mating itself. Moreover, our studies suggest a third role for ceramide in localizing the mating-specific Ste5 scaffold to the plasma membrane. Thus, ceramide plays a role 1) in pheromone-induced cell cycle arrest, 2) in activation of MAP kinase-dependent transcription, and 3) in PtdIns(4,5)P2 polarization. All three events are required for differentiation during yeast mating. © 2016 Taylor & Francis.
Klein C.,University Hospital of Tuebingen |
Sprecher C.,AO Research Institute Davos |
Rahn B.A.,AO Research Institute Davos |
Green J.,Synthes Inc. |
Muller C.A.,Stadtisches Klinikum Karlsruhe
Injury | Year: 2010
The purpose of the present study was to evaluate the Reamer/Irrigator/ Aspirator (RIA), a reaming system designed to incorporate the advantages of irrigation and suction for every day clinical use. The evaluation process was focused on the displacement of the medullary content and its impact on cortical perfusion. The results of the RIA reamed nailing were compared to conventional non-reamed nailing (NRN). The tibia of the sheep was used as an acute fracture model. The fracture and nailing procedure was followed by intravital staining with Procion red. The effects on cortical perfusion (Procion red staining) were addressed in polymer embedded sections and cryosections. Sudan III stained cryosections were evaluated with respect to the cortical fat distribution. After irrigation and suction minute amounts of fat were observed in the cortex, whereas after non-reamed nailing the endosteal third of the cortical bone was penetrated with fat. Non-reamed nailing acutely showed better perfusion in the endosteal tenth and periosteal third of the cortical bone, after irrigation and suction reaming perfusion was preserved to a lesser degree. Irrigation and suction significantly reduces fat intravasation, and thus the danger of system-wide damage. Therefore, the Reamer/Irrigator/Aspirator is as efficient as its experimental predecessors. © 2010 Elsevier Ltd. All rights reserved.
Tschegg E.K.,Vienna University of Technology |
Lindtner R.A.,Innsbruck Medical University |
Doblhoff-Dier V.,University of Natural Resources and Life Sciences, Vienna |
Stanzl-Tschegg S.E.,University of Natural Resources and Life Sciences, Vienna |
And 4 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2011
Bioresorbable materials for implants have become increasingly researched over the last years. The bone-implant-interfaces of three different implant materials, namely a new bioresorbable magnesium alloy, a new self-reinforced polymer implant and a conventional titanium alloy, were tested using various methods: push-out tests, SEM and EDX analyses as well as surface analyses based on stereoscopic 3D pictures were conducted. The fracture energy is proposed as a very significant reference value for characterizing the mechanical performance of a bone-implant system. By using a video-extensometer system instead of, as is commonly done, tracking the movement of the crosshead in the push-out tests, the accuracy of measurement could be increased. © 2010 Elsevier Ltd.
Dunkers J.P.,U.S. National Institute of Standards and Technology |
Lee H.-J.,U.S. National Institute of Standards and Technology |
Matos M.A.,U.S. National Institute of Standards and Technology |
Matos M.A.,Boeing Company |
And 5 more authors.
Acta Biomaterialia | Year: 2011
When culturing cells on flexible surfaces, it is important to consider extracellular matrix treatments that will remain on the surface under mechanical strain. Here we investigate differences in laminin deposited on oxidized polydimethylsiloxane (PDMS) with plasma treatment (plasma-only) vs. plasma and aminopropyltrimethoxysilane treatment (silane-linked). We use specular X-ray reflectivity (SXR), transmission electron microscopy (TEM), and immunofluorescence to probe the quantity and uniformity of laminin. The surface coverage of laminin is approximately 45% for the plasma-only and 50% for the silane-linked treatment as determined by SXR. TEM and immunofluorescence reveal additional islands of laminin aggregates on the plasma-only PDMS compared with the relatively smooth and uniform silane-linked laminin surface. We also examine laminin retention under strain and vascular smooth muscle cell viability and proliferation under static and strain conditions. Equibiaxial stretching of the PDMS surfaces shows greatly improved retention of the silane-linked laminin over plasma-only. There are significantly more cells on the silane-linked surface after 4 days of equibiaxial strain.
Synthes Llc | Date: 2010-09-22
A soft tissue repair system includes a needle, a sheath, and a actuator. The needle has a body and a tip that extends distally from the body. The body defines a longitudinal channel configured to hold a plurality of suture anchors, and an ejection port proximal to the tip. The needle is configured to receive and hold a strand of suture. The sheath is disposed coaxially around the exterior of the needle, and is translatable with respect to the needle between a first position, and a second position. The actuator is translatable within the needle channel and is configured to push the suture anchors distally such that a first suture anchor of the plurality of suture anchors engages the suture strand held by the needle and sheath.