Stable Implantation Research Articles

The percutaneous treatment of Patent Foramen Ovale, an effective and safe therapeutic choice

Abstract

Modular acetabular reconstructive cup in acetabular revision total hip arthroplasty at a minimum ten year follow-up

Modular acetabular reconstructive cups have been introduced in an attempt to offer initial rigid fixation by iliac lag screws and ischial pegs, to support bone grafts with a flanged metal socket, and to restore original hip center in acetabular revision. The purpose of this study was to clarify minimum ten year follow-up results of this cup system with morsellised allografts in revision cases. We retrospectively investigated 54 acetabular revisions at a mean of 11 years (range, ten to 14 years). The indications were Paprosky's type 2B (eight hip), 2C (eight hips), 3A (23 hips), 3B (nine hips), and 4 (six hips). Using aseptic loosening as the endpoints, the survival rate was 89.3 % (95 % CI 81-98). Radiographically, one type 3A hip, three type 3B hips and one type 4 hip showed aseptic loosening while no type 2 hips or no cemented cups showed loosening. The modular reconstructive cups for acetabular revision showed bone stock restoration and stable implantation.

Implantation of unmarked regulatory and metabolic modules in Gram-negative bacteria with specialised mini-transposon delivery vectors

Engineering of robust and safe microbial cell factories requires genetic tools somewhat different from those traditionally used for laboratory-adapted microorganisms. We took advantage of the properties of broad-host-range mini-Tn5 vectors and two regulated expression systems (LacIQ/Ptrc and XylS/Pm), together with FRT-flanked, excisable antibiotic resistance determinants, to generate a set of vectors for the delivery of gene(s) into the chromosome of Gram-negative bacteria. This arrangement of modular elements allows the cloning and subsequent markerless insertion of expression cargoes and leaves behind an antibiotic-sensitive host upon the action of the yeast Flp recombinase. We engineered a Pseudomonas putida KT2440 Pm::gfp strain that displayed strong fluorescence upon exposure to 3-methylbenzoate, a XylS effector, and allowed us to examine the performance of the Pm promoter at the single cell level. We also reconstructed a device for sugar transport and phosphorylation in Escherichia coli independent of the native phosphoenolpyruvate-dependent phosphotransferase system by the stable implantation of genes derived from the obligate anaerobe Zymomonas mobilis. In both cases, the information carried by the implanted genes was stably inherited in the absence of any selective pressure. Deliverable expression systems such as those described here will enhance the applicability of various Gram-negative bacteria in biocatalysis and environmental bioremediation.

How bone forms in large cancellous defects: Critical analysis based on experimental work and literature

The behaviour of physiological biomaterials, β-tricalciumphosphate and hydroxyapatite, is analysed based on current literature and our own experimental work.The properties of graft substitutes based on ceramic materials are clearly defined according to their scientific efficiency. The strength of the materials and their biodegradability are still not fully evaluated. Strength and degradability have a direct proportional relationship and are considered the most efficient way to be adapted by their properties to the needs for the treatment of bone defects. New technologies for the manufacturing process are presented that increase those properties and thus open up new indications and easier application of the ceramic materials. The implantation process as well is carefully validated by animal experiments to avoid failures. Based on the experiments, a completely new approach is defined as to how primary bone formation with osteoconductive ceramics can be achieved. The milestones in that approach comprise a synthetically manufactured replica of the bone marrow spaces as osteoconductive ladder, whereas the bead is defined as bone-forming element. As a result, materials are available with high strength if the ceramic is solid or highly porous and possesses a micro-structure. The injection moulding process allows for the combination of high strength of the material with high porosity. Based on the strong capillary forces, micro-chambered beads fulfil most expectations for primary bone formation in cancellous bone defects, including drug delivery, mechanical strengthening if necessary, and stable implantation in situ by coagulation of the blood and bone marrow suctioned in.

Single Molecule Binding of CD44 to Fibrin Versus P-selectin Predicts Their Distinct Shear-dependent Interactions in Cancer

P-selectin and fibrin(ogen) play pivotal roles in the hematogenous dissemination of tumor cells. CD44 variant isoforms, CD44v, have been identified as the major functional P-selectin ligands and fibrin receptors on metastatic colon carcinoma cells. In vivo P-selectin mediates the initial binding/seeding and subsequent lodging of metastatic tumor cells in target organs, whereas fibrin(ogen) supports their sustained adhesion and stable implantation. In vitro the molecular recognition of CD44v by fibrin mediates firm adhesion at low shear, whereas CD44v-P-selectin binding supports transient rolling interactions at elevated shear stresses and low P-selectin site densities. We used single molecule force spectroscopy to provide a molecular interpretation for these two distinct adhesion events. We demonstrate that the CD44v-P-selectin relative to the CD44v-fibrin bond has a longer unstressed equilibrium lifetime, a lower susceptibility to rupture under force, and a higher tensile strength. These intrinsic differences confer the ability to the CD44v-P-selectin pair to mediate binding at higher shear stresses. Increasing the receptor-ligand contact duration (2-200 ms) did not affect the micromechanical properties of CD44v-P-selectin bond, but it increased the tensile strength of the CD44v-fibrin bond. The CD44v-fibrin bond maturation is further supported by the rapid decrease in reactive compliance and the increase in the depth of the free energy barrier of this biomolecular interaction. This bond strengthening at longer interaction times explains why CD44v binding to immobilized fibrin occurs at low shear and correspondingly high contact durations. Single molecule characterization of receptor-ligand binding can predict the shear-dependent cell-substrate adhesive interactions observed in vitro and in vivo.

An intraoperatively moulded PMMA prostheses like spacer for two-stage revision of infected total knee arthroplasty

We report a series of 16 consecutive total knee arthroplasty (TKA) revision procedures for deep infection, treated with a newly developed intraoperatively moulded PMMA cement-prostheses-like spacer (CPLS). The standard treatment consisted of a two-stage protocol with initial explantation of the infected components combined with radical debridement, followed by implantation of a temporary cement spacer and final reimplantation of a new TKA. A sterilizeable Teflon tapered aluminium mould was developed for production of a custom made CPLS during the intervention. Stable implantation of the CPLS was achieved with a second cementation, allowing for correct alignment and ligament balancing. The spacer remained 3.5 months on average until reimplantation of a TKA occurred. At time of reimplantation, patients had an average KSS score of 84.44 points with an average flexion capacity of 102°. There was no recurrent infection during the study period of minimum 2 years. With this new technique, a low friction articulation with good stability, high comfort and a better range of motion compared to handcrafted spacers was achieved. The use of this spacer is a time sparing, cheap and convenient option in 2-stage TKA revision.

Applied Anatomic Site Study of Palatal Anchorage Implants Using Cone Beam Computed Tomography

AimThe purpose of this study was to conduct quantitative research on bone height and bone mineral density of palatal implant sites for implantation, and to provide reference sites for safe and stable palatal implants.MethodologyThree-dimensional reformatting images were reconstructed by cone beam computed tomography (CBCT) in 34 patients, aged 18 to 35 years, using EZ Implant software. Bone height was measured at 20 sites of interest on the palate. Bone mineral density was measured at the 10 sites with the highest implantation rate, classified using K-mean cluster analysis based on bone height and bone mineral density.ResultsAccording to the cluster analysis, 10 sites were classified into three clusters. Significant differences in bone height and bone mineral density were detected between these three clusters (P<0.05). The greatest bone height was obtained in cluster 2, followed by cluster 1 and cluster 3. The highest bone mineral density was found in cluster 3, followed by cluster 1 and cluster 2.ConclusionCBCT plays an important role in pre-surgical treatment planning. CBCT is helpful in identifying safe and stable implantation sites for palatal anchorage.

Evaluation of the implant sites of palatal implants using cone beam computed tomography

To investigate the vertical bone height and the bone density of the palate for implants placement using cone beam CT(CBCT) and to provide references to the safe and stable placement of palatal implants. Three-dimensional reformatting images were reconstructed with the selected CBCT scanning data of 34 patients aged 18 to 35 yeras, by means of EZ implant software. The vertical bone height was measured at 20 interesting sites of palate. Bone density was measured at 10 sites that could support 3.0 mm long implants. The data of the vertical bone height and bone density were analyzed by K-means cluster analysis. According to the cluster analysis results, the 10 sites were classified into 3 clusters. There were statistical differences among these three clusters in bone height and bone density (P < 0.05). The LSD result showed that the greatest mean value of vertical bone height was obtained in cluster 2, followed by cluster 1 and cluster 3; the highest bone density was founded in cluster 3, followed by cluster 1 and cluster 2. Evaluation of the sites for palatal implant placement with cone beam CT would be helpful in safe and stable implantation.

Energy spike effects in ion-bombarded GaN

We study structural disorder in GaN bombarded at room temperature with 1.3 keV amu−1 PFn (n = 0, 2 and 4) cluster ions. Results are compared with our previous studies of irradiation with atomic ions of different masses. An algorithm for cascade density calculations that take into account the formation of subcascades is presented. Quantitative analysis of both new and previous data shows that an increase in the cascade density above a certain critical value results in a rapid increase in the rate of planar amorphization and the rate of damage buildup in the crystal bulk. Both such rates increase with decreasing sample temperature. This threshold-like behaviour suggests an important role of nonlinear energy spikes in the formation of stable implantation disorder in GaN. We also discuss the striking difference between cascade density effects in damage buildup in different semiconductors, including GaN, ZnO and Si.

Stable implantation of orthogonal sensor circuits in Gram‐negative bacteria for environmental release

A broad host range, orthogonal genetic platform has been developed to format sensor circuits in the chromosome of Gram-negative microorganisms destined for environmental release as bioindicators of toxic or perilous compounds (e.g. explosives) in soil. The genetic scheme includes the generation of a genomic landing pad for the sensor module with a Tn5-mini-transposon bearing an optimal attTn7 sequence and a choice of reporter systems with optical and enzymatic outputs. The array of functional elements thereby inserted in the chromosome match that of a cognate plasmid vector which delivers the transcription factors and the promoters to a frame that places the regulatory parts in front of the reporters. Site-specific recombination sites allow the deletion of antibiotic resistances and enables reporter output prior to deliberate release. The system thus allows the production and maintenance of cells in a pre-release state and its intentional conversion in deliverable strains that fulfil all safety, stability and performance criteria. The combination of such a genetic platform with a variant of the transcriptional regulator XylR of Pseudomonas putida that responds to 2,4-dinitrotoluene has been the basis for the production of strains that emit light upon exposure to residues of explosives in a soil microcosm.

Anatomically adapted, HA coated SBG stem – Ten years of successful implantation / Anatomisch adaptierte, HA beschichtete SBG Prothese – 10 Jahre erfolgreiche Anwendung

For stable implantation of anatomically conforming femur prostheses, modifications that accommodate curving and torsion are necessary. In accordance to this concept, the anatomically shaped SBG stem has been developed. The first consecutive implantations were evaluated. 194 primary arthroplasties with uncemented anatomical, HA coated SBG stems were performed. Mean patient age was 61 years. 143 patients with 151 (78%) SBG stems were followed-up clinically and radiologically after an average of 10 (9-11) years. So far, only one implant had to be revised. Survivorship with revision of the femoral component is 99.5% at ten years. The mean postoperative Harris Hip Score was 92. Patients over 75 years had a score of 89; younger patients under 40 years scored 94. Sclerotic lines were seen in zone I or VII in 8%. Minor femoral remodeling (Type 1) occurred proximally in 75%. Minor thickening of the femur at the level of the tip of the prosthesis could be observed in 27% of the cases. There is no correlation between compacta thickening and clinical symptoms (p=0.15). The anatomical shape, the oval diameter and the longitudinal grooves secure stable primary fixation. Together with the HA coating, which enhances osseointegration, the SBG stem has a high success rate in the medium and long term.

Photoelastic and thermoelastic measurement of stress on the proximal femur before and after implantation of a hip prosthesis with retention of the femoral neck.

This study demonstrated the improved medial support and the transfer of load onto the retained neck of the femur using seven fresh frozen femurs. Results confirm the reliability of the thermoelastic stress analysis method, which is comparable to the photoelastic surface coating method, but with greater sensitivity. The loading pattern after stem implantation shows a homogeneous transfer of force onto the preserved femoral neck. After femoral neck removal, an inhomogeneous increase of the intertrochanteric compression loading was observed. Therefore, improved biomechanical conditions are created for a permanently stable implantation of stem prostheses with retention of the femoral neck.

Interaction between Fe, dopants, and secondary defects in MeV Fe ion implanted InP

We investigate the role of damage production and annealing in determining the Fe redistribution properties when implanting Fe at MeV energies in n-type InP. Fe ion implantation is performed at 2 MeV on (100) InP substrates, both undoped and Sn doped (1.5×1018 cm−3). Implants are performed both at room temperature (RT) and at 200 °C (HT), with doses ranging from 1×1013 to 1.2×1015 cm−2. A double implantation experiment is also performed, coimplanting Fe and P to investigate the influence of the P induced damage on the Fe redistribution/accumulation. Annealing is performed in the temperature range between 650 and 800 °C using flowing phosphine to prevent surface decomposition. To characterize the damage of our samples before and after annealing we employ Rutherford backscattering spectrometry in channeling condition and transmission electron microscopy; Fe depth profiles are measured by secondary ions mass spectrometry. A strict correlation is found between the position of Fe accumulation peaks and that of secondary defects formed in RT implanted samples during annealing; in particular it is shown that end of range dislocation loops and interfaces between damaged and undamaged crystal regions act as gettering sites for Fe atoms. The accumulation process is controlled by Fe diffusion that is greatly enhanced by the presence of mobile point defects related to the implantation damage; on the contrary it is shown that Sn doping has a strong retarding action on Fe diffusion. It is demonstrated that the strong reduction in damage production related to dynamic annealing in HT implantation can be used to reduce or avoid Fe redistribution/accumulation phenomena, leading to fairly stable implantation profiles also for high annealing temperatures and long annealing times.

Selective Implantation Patterning and MBE Regrowth for Integration of Mm-Wave Application Heterojunction Devices

ABSTRACTA technology based on a combination of selective implantation for lateral patterning and a following large area regrowth by molecular beam epitaxy (MBE) is introduced. The technology allows the monolithic integration of devices with different vertical layer sequences on s.i. GaAs substrates in a quasi planar way, e.g. a heterojunction field-effect-transistor (HFET) with a Schottky diode or a MESFET with a Schottky diode. Selective high resistive (&gt;109 Ω/sq) and highly conducting (&lt;20Ω/sq) buried layers are fabricated by high temperature stable oxygen and silicon implantation, respectively. The following MBE regrowth of epitaxial layers yields to an excellent surface morphology. HFET structures with pseudomorphic AlGaAs/InGaAs/GaAs heterostructures grown on implanted substrates exhibit a strong photoluminescence response. Carrier densities up to 2.0×1012cm−2 (1.6×1012cm−2) and Hall mobilities of 6150 cm2/Vs (17700 cm2/Vs) at 300 K (80 K) in the dark are achieved. The material quality is drastically improved by substrate preparation and in-situ cleaning prior to MBE regrowth.

Knochentransplantation — Indikation und Technik

Autogenous spongiosa or, in osteoplastic surgery, autogenous corticospongious bones are considered as substance of choice for the surgical transposition of missing bones, to strengthen bones with insufficient loading capacity, and for a biological activation of atrophic bones. Even deep-freeze allogenous spongiosa can be inserted into a sterile, stable implantation site able to absorb the spongiosa to a large extent. The success will be delayed, but in the end a good functional result will be achieved with this method. In case of such an optimum implantation site, a comparable therapeutic effect can also be obtained with osteoinductive ceramics which can be modified with respect to their osteoinduction and loading capacity, both values showing a reciprocal ratio. Xenogenous bone grafts are no longer applied. A clinical example is presented in order to describe some criteria for the choice of a suitable transplant and to give some practical indications for its therapeutic application.