Short Implantation Research Articles

In vitro and In vivo Degradation Evaluation of Mg-Based Alloys for Biomedical Applications

Biodegradable metals have attracted interest for implant applications because of the potential to eliminate secondary surgeries. Magnesium-based (Mg-based) alloys are potential candidates. The purpose of this study was to evaluate the in vitro and in vivo degradation performances of two custom-made magnesium-based alloys and to determine whether they are sustainable for further investigation. The performances of Magnesium-Zinc-Manganese (Mg-Zn-Mn) alloys at 5% and 1% zinc levels were compared using a mechanical test, hydrogen evolution test, cell viability (MTT) test, and a short term mice subcutaneous implantation. The results showed that the corrosion resistance of the Mg was improved by alloying. While Mg-5Zn-1Mn was more corrodible compared with Mg-1Zn-1Mn, neither of the alloys presented any adverse effects preliminarily and both were suitable for long-term testing for biomedical applications.

Cytotoxicity of gold nanoparticles in human neural precursor cells and rat cerebral cortex

Nanoparticles are promising tools for the advancement of drug delivery, medical imaging, and as diagnostic sensor. Medical nanodevices should develop miniaturization, because it would be injected into a human body. Gold nanoparticles (GNPs) with different sizes and shapes have therapeutic potential as a result of their small size, robust nature, excellent biocompatibility and optical properties. However, the application of GNPs as medical nanodevices it is necessary to know the biodegradation, biocompatibility, and development of surface coating which avoid the accumulation of nanoparticles. In this study, we carry out an in vitro toxicity and in vivo gene expression study using two kinds of GNPs. We found that GNPs toxicity is dependent on the dose or size administrated after the injected GNPs into the brain, and small particle size GNPs appeared more nestin expression compared to large particle size at short term implantation. These findings of toxicity of GNPs may play an important role in development of in vivo tools for the safety of GNPs.

Desmoglein-2 during pregnancy and its role in the evolution of viviparity in a marsupial (Sminthopsis crassicaudata; Dasyuridae).

Attachment of the blastocyst and formation of the placenta during pregnancy is dependent on structural and cellular changes occurring in the uterine epithelium and in particular to the plasma membrane of these uterine cells. Desmosome expression decreases during pregnancy in eutherians and some squamates, presumably allowing for remodeling of the uterine epithelium and invasion of the trophoblast during implantation. Marsupials are a distinct mammalian amniote lineage of viviparity, with a short implantation or attachment period and varying levels of invasive placentation. To test the generality of changes to the uterine epithelium during pregnancy across mammals, we characterized the distribution of desmosomes in the uterine epithelial cells of a marsupial, Sminthopsis crassicaudata, using electron microscopy and immunohistochemistry. The absolute number of desmosomes along the lateral plasma membrane decreases during pregnancy and desmosomes are redistributed towards the apical region of the lateral plasma membrane as pregnancy proceeds, similar to what occurs during pregnancy in eutherian mammals. Despite the lower level of maternal investment in pregnancy and the noninvasive structure of fetal membranes in marsupials there are similarities in number and redistribution of desmosomes along the plasma membrane and changes to the morphology of the uterine epithelial cells suggesting that similar plasma membrane changes occur across all lineages of amniote vertebrates.

Outcomes after implantation of partial-support left ventricular assist devices in inotropic-dependent patients: Do we still need full-support assist devices?

Partial-support left ventricular assist devices (LVADs) represent a novel strategy for heart failure treatment. The Synergy Pocket Micro-pump (HeartWare Inc, Framingham, Mass), the smallest surgically implanted long-term LVAD, provides partial flow up to 4.25 L/min and was primarily designed for "less sick" patients with severe heart failure. This device is implanted minimally invasively without sternotomy or cardiopulmonary bypass. Early implantation in patients with Interagency Registry for Mechanically Assisted Circulatory Support class 4 and higher was shown to be feasible and associated with significantly improved hemodynamics and quality of life. The aim of this study was to present our experience with implementation of long-term partial circulatory support as a bridge to transplantation in patients with more advanced heart failure who were dependent preoperatively on inotropic support or intra-aortic balloon pump. In this observational study, only inotropic or intra-aortic balloon pump-dependent patients with end-stage heart failure were included (n = 12). These patients underwent Synergy device implantation between February 2012 and August 2013. The mean preoperative Interagency Registry for Mechanically Assisted Circulatory Support class was 2.17 ± 0.84 (class 1, 25%; class 2, 33%; class 3, 42%). The mean age was 46 ± 15 years, and 33% were female. Preoperatively, 4 patients (33%) had at least 1 previous sternotomy, 3 patients (25%) were supported with a balloon pump, 1 patient (8%) had a previous full-support LVAD, and 4 patients (33%) had cerebrovascular events in the past. After device implantation, there were no right ventricular failures, device-related infections, hemorrhagic strokes, arterial or venous thromboembolisms, or worsenings of aortic and mitral regurgitation observed over the follow-up. The mean follow up was 174 ± 171 days (range, 5-764 days; cumulative, 3199 days). One patient (8%) died, 3 patients (25%) successfully underwent transplantation, 1 device (8%) was explanted after myocardial recovery, and 5 patients (42%) are still on ongoing support. Two patients (17%) were upgraded to a full-support LVAD after 65 days of mean support. A total of 11 of 12 patients (92%) were discharged from the hospital and are presently alive. Left ventricular end-diastolic diameter was significantly reduced 3 months after device implantation. Partial LVAD support may be clinically efficacious in inotropic and intra-aortic balloon pump-dependent patients. On the basis of our experience and evidence of previous research, such patients may benefit from minimally invasive access, no need for sternotomy and cardiopulmonary bypass, a short implantation time, an easy exchange if necessary, and a lower risk of subsequent heart transplantation. Because the implantation is performed without sternotomy, device upgrade is feasible with a comparatively low operative risk and good clinical outcome. Our preliminary results show that partial-support devices may have the potential to replace full-support LVADs in the near future.

Titanium macroparticles density decreasing on the sample, immersed in plasma, at repetitively pulsed biasing

Abstract We have studied the features of the Ti macroparticles (MPs) accumulation on a substrate immersed in a DC vacuum arc plasma with a high frequency short pulse negative bias. The influence of several factors including processing time, the parameters of bias potential, and substrate characteristics was defined. It was found that the MP accumulation on a repetitively biased substrate was uneven over time. A deposition of MPs to substrate were significantly decreased after 1 min of processing at bias parameters f = 10 5 p.p.s., φ b = −2 kV and τ = 7 μs. It was experimentally shown that DC vacuum arc plasma without pre-filtering of MPs can be used for high frequency short pulse plasma immersion metal ion implantation.

Sutureless aortic valves - a word of cautione single-centre experience with the Medtronic 3f Enable™ Prosthesis

Introduction: Recent data suggest that aortic valve replacement (AVR) using the sutureless self-expanding Medtronic Enable™ bioprosthesis is safe and feasible with excellent hemodynamics and a short implantation time. After experiencing 5 cases of severe paravalvular leakage/valve dislocation we critically reviewed all patients who had undergone AVR with the Medtronic Enable™ valve at our institution.

Early osseointegration of a strontium containing glass ceramic in a rabbit model

The most important property of a bone cement or a bone substitute in load bearing orthopaedic implants is good integration with host bone with reduced bone resorption and increased bone regeneration at the implant interface. Long term implantation of metal-based joint replacements often results in corrosion and particle release, initiating chronic inflammation leading onto osteoporosis of host bone. An alternative solution is the coating of metal implants with hydroxyapatite (HA) or bioglass or the use of bulk bioglass or HA-based composites. In the above perspective, the present study reports the in vivo biocompatibility and bone healing of the strontium (Sr)-stabilized bulk glass ceramics with the nominal composition of 4.5SiO2–3Al2O3–1.5P2O5–3SrO–2SrF2 during short term implantation of up to 12 weeks in rabbit animal model. The progression of healing and bone regeneration was qualitatively and quantitatively assessed using fluorescence microscopy, histological analysis and micro-computed tomography. The overall assessment of the present study establishes that the investigated glass ceramic is biocompatible in vivo with regards to local effects after short term implantation in rabbit animal model. Excellent healing was observed, which is comparable to that seen in response to a commercially available implant of HA-based bioglass alone.

Two-year Comparison of Lesional Outcomes of Long Versus Short Drug-eluting Stent in One Patient with Two Vessel Disease

Diffuse long coronary artery lesion remain difficult to treat in the era of durg-eluting stent (DES). The purpose of this study is to compare lesional outcomes of long and short stent implantation in one patient with two vessel disease.

Corrosion Resistant Titanium Alloys for Medical Tools and Implants

New corrosion resistant Ti-8Ni-Cr system alloys with increased hardness and strength have been developed for medical tools and implants. The development was made based on study of chromium influence on the phase constituents, microstructure, mechanical properties, corrosion resistance and electrochemical characteristics of Ti- 8Ni alloy. Optimum condition of thermal treatment, providing high strength, hardness and corrosion resistance of alloys has been defined – quenching from 950°C with content of chromium in alloys 1 – 3% (by addition of Yttrium in quantity 0,001 – 0,01 mass%). The cause is that alloys after quenching from 950°C have structure of transformed β-solid solution and contain ω-phase, which is micro dispersive during concentration of chromium up to 1-3%. On the base of studying of the phase equilibrium by microstructural, x-ray investigations and differential thermal analysis of Ti-8Ni-Cr system alloys polythermal sections of phase diagram of this system have been constructed, which is in complete accordance with the phase diagram formed by thermodynamic calculations. Study of mechanical properties of Ti-8Ni-(0-3) Cr quenching alloys show, that chromium increases the tensile strength (1000MPa) and hardness (48 HRC) and slightly influences on plastic properties of the Ti-8Ni alloy. Tensile strength of titanium commercial alloys: Ti-6Al-4V and Ti-5Al-3Sn do not exceed 900 MPA. Corrosion tests in medium containing human body: blood, physiological solution, gastric juice, tissue liquid and also corrosion testing according to the following regime: cleaning+disinfection+sterilization in aggressive solutions with addition of hydrogen peroxide reveal high corrosion resistance of Ti-8Ni-(0-3)Cr alloys, without the changing of surface. After 20 cycles corrosion losses of the commercial titanium alloys are ~ one order more than the losses of new alloys. Study of toxic properties of alloys Ti- 8Ni-(1-3)Cr during their implantation in muscles and abdominal cavity of animals show, that they do not cause local irritative actions on different tissues, they do not suppress local tissue reactions and do not have any toxic effects during short or long term implantation conditions. High corrosion resistance of alloy Ti-8Ni-1Cr is established also by the modeling and prediction of corrosion behavior in the physiological solution at the temperature 37oC with using of electrochemical investigations, spectral analysis, regression and variance analysis of the mathematical statistics. Alloys Ti-8Ni-(1-3)% Cr are recommended for manufacturing high-strength medical tools of multiply usage and surgical implants. Application of new alloys will allow improving functional properties and increase quality, reliability, service life of medical tools and implants.

The influence of resection height on proximal femoral strain patterns after Metha short stem hip arthroplasty: an experimental study on composite femora

The number of candidates for a total hip arthroplasty (THA) is steadily increasing, while the average patient age is decreasing for primary THA. The rise in THA is mainly due to excellent clinical outcomes and the extended longevity of modern implants. Short stem arthroplasties with predominantly metaphyseal fixation such as the Metha® stem are suggested for young patients. It is hypothesised that the more physiological load transfer of these devices reduces stress shielding, which in turn may reduce the risk of aseptic loosening. However, patients with femoral deformities often require a deviation of the resection height. To this end, our aim was to evaluate how resection height influences strain patterns in order to characterise possible limits for short stem implantation. Biomechanical testing using ten strain gauges on synthetic bone illustrated the strain patterns of three different resection heights (0, +5 and +10 mm) for the Metha stem. The greatest differences in strains were displayed at the "high" (most proximal) resection height (+10 mm) when compared to the non-implanted strain pattern. At the medial calcar, the strain was 143% for +10 mm, 96% for +5 mm and 94% for 0 mm. Overall, discrepancies were less for deeper resections. The deeper the resection, the more similar the strain patterns are when compared to a non-implanted synthetic bone. Changes in strain patterns are induced by variation in the varus/valgus positioning of the implant and by different offsets.

Comparison of manual rasping and robotic milling for short metaphyseal-fitting stem implantation in total hip arthroplasty: a cadaveric study

Objective: The ROBODOC system offers the theoretical advantage of providing better fit and mechanical stability of the stem in total hip arthroplasty. However, there has been no previous study on short metaphyseal-fitting stem implantation using the ROBODOC system. The aim of the present study was to compare the implant position and primary stability of short metaphyseal-fitting stems implanted by robotic milling and manual rasping in a human cadaveric femoral model.Methods: Eight matched pairs of human cadaveric femora were randomly assigned to a robotic milling group or manual rasping group. Operative time and intraoperative femoral fractures were monitored, and radiographic evaluation of stem alignment was performed by comparison of preoperative planning and postoperative CT data. Stability testing was performed on six matched pairs of femora, excluding two specimens in which intraoperative fractures occurred.Results: The robotic milling procedures took an average of 27 minutes longer than the manual rasping procedures (p < 0.001). The robotic milling group exhibited significantly better anteroposterior alignment and vertical seating, and also showed a significantly reduced variability in both alignment and vertical seating. No intraoperative femoral fracture was detected in the robotic milling group, whereas two femoral fractures and one femoral stem tip perforation were detected in the manual rasping group. Stability testing showed no significant difference in translational and rotational migrations between the two groups, although the robotic milling group showed a trend towards reduced variability of stability.Conclusions: Our cadaveric study suggests that the use of the ROBODOC system for short metaphyseal-fitting stem implantation may have advantages in improving implant fit and reducing the risk of intraoperative femoral fractures without compromising primary stability.

AS-057: Comparison of Lesional Outcomes of Long versus Short Drug-Eluting Stent in One Patient with Two Vessel Disease

Diffuse long coronary artery lesion remain difficult to treat in the era of drug-eluting stent (DES). The purpose of this study is to compare lesional outcomes of long and short stent implantation in one patient with two vessel disease.

An In Vitro and In Vivo Study on the Intensity of Adhesion and Colonization by Staphylococcus epidermidis and Pseudomonas aeruginosa on Originally Synthesized Biomaterials With Different Chemical Composition and Modified Surfaces and Their Effect on Expression of TNF-α, β-Defensin 2 and IL-10 in Tissues

The aim of this study was to determine adhesion and colonization of bacteria on the surface of originally synthesized glass-ceramic biomaterials and their effect on inflammation reactions in tissues surrounding the implant. Biomaterial discs were contaminated with bacterial suspensions of 10, 10(2), and 10(3) colony forming units (CFU)/mL (P. aeruginosa ATCC 27853 and S. epidermidis ATCC 12228), and after 2 hours of cultivation, the intensity of bacterial adhesion was determined. For in vivo tests, the samples were contaminated with 102 and 103 CFU/mL cultivated at 37°C for 2 h to ensure bacterial adhesion. Contaminated biomaterial samples were implanted in the interscapular area of chinchilla rabbits for 2 and 4 weeks. The biomaterials were removed, and using plate count and sonification methods, bacterial colonization on the surface of biomaterials was determined. Moreover, the expression of TNF-α, β-defensin 2, and IL-10 in the surrounding tissues was assessed by using immunohistochemistry methods. P. aeruginosa more intensively colonized biomaterials in the in vivo study as compared with S. epidermidis. Il-10 is a regulatory cytokine, which reduces the intensity of inflammatory cell activity, thus reducing nonspecific resistance of the organism. The expression of TNF-α and IL-10 was not affected by short (2 and 4 weeks) biomaterial implantation. Pronounced cytokine expression in tissues around implanted biomaterials contaminated with P. aeruginosa was observed.

Long term performance of polycaprolactone vascular grafts in a rat abdominal aorta replacement model

In the active field of vascular graft research, polycaprolactone is often used because of its good mechanical strength and its biocompatibility. It is easily processed into micro and nano-fibers by electrospinning to form a porous, cell-friendly scaffold. However, long term in vivo performance of polycaprolactone vascular grafts had yet to be investigated. In this study, polycaprolactone micro and nano-fiber based vascular grafts were evaluated in the rat abdominal aorta replacement model for 1.5, 3, 6, 12, and 18 months ( n = 3 for each time point). The grafts were evaluated for patency, thrombosis, compliance, tissue regeneration, and material degradation. Results show excellent structural integrity throughout the study, with no aneurysmal dilation, and perfect patency with no thrombosis and limited intimal hyperplasia. Endothelialization, cell invasion, and neovascularization of the graft wall rapidly increased until 6 months, but at 12 and 18 months, a cellular regression is observed. On the medium term, chondroid metaplasia takes place in the intimal hyperplasia layers, which contributes to calcification of the grafts. This study presents issues with degradable vascular grafts that cannot be identified with short implantation times or in vitro studies. Such findings should allow for better design of next generation vascular grafts.

An initial assessment of the biocompatibility of crab shell for bone tissue engineering

There is a kinship that exists among biologically derived hard tissues. This inter-relatedness is expressed via comparable mechanisms for organic matrix organization and biomineralization processes. The ability to use biogenic hard tissues such as coral and nacre in augmentation of damaged bone tissue further attests to the unique bonds which are shared by hard tissues in nature. Crab shell cuticle is another candidate material for enhancing the healing and remodeling of bone. A comparison of the unique chemical and physical characteristics of bone and crab shell with a focus on the respective organic matrices and mineral phases serves as the focus for this study of crushed crab shell as an osteogenic material. L929 murine fibroblasts were used to assess the initial biocompatibility of crab shell granules. Short term subcutaneous implantation of demineralized crab shell granules in the abdominal region of 28 day old Sprague–Dawley rats resulted in a high level of localized monocyte and macrophage like cells that digested the shell granules in a manner reminiscent of osteoclasts. The presence of early stage collagen fiber bundles with interspersed mineral crystals within the first week suggests that crab shell exhibits osteogenic properties.

C005 Short sequential bilateral cochlear implantation in children

C005 Short sequential bilateral cochlear implantation in children

Formation of Nano Diamonds in Surface Layer of Materials during Short Pulse Ion Beam Implantation

Formation of Nano Diamonds in Surface Layer of Materials during Short Pulse Ion Beam Implantation

Freedom SOLO valve: early- and intermediate-term results of a single centre's first 100 cases

The Freedom SOLO aortic valve is a bovine pericardial stentless valve, which requires only one suture line. The aim of our single-centre retrospective study was to assess postoperative and intermediate-term haemodynamic results of the first 100 consecutively implanted valves. One hundred patients (39 male and 61 female) underwent aortic valve replacement with a Freedom SOLO from November 2006 to January 2008. Their clinical, operative, platelet levels, echocardiography and follow-up data were prospectively recorded. All but two patients were available for follow-up (98% completeness), which averaged 12.6 ± 5.06 months. Associated procedures were performed in 38 patients (38%): 27 coronary artery bypass grafting (CABG), 11 mitral valve replacement, 11 septal myectomy and one ablation for atrial fibrillation. The mean age at the time of surgery was 77.2 ± 6.43 years. The mean European System for Cardiac Operative Risk Evaluation (EuroSCORE) was 8.05 ± 2.07. Mean cross-clamp time of isolated valve replacements was 51.27 ± 4.7 min and 63.18 ± 21.7 min with associated procedures. The mean implanted valve size was 23.5 ± 1.9 mm. One patient was re-operated for bleeding, two for pericardial effusion and 39 were transfused. The overall hospital mortality was 3%. One patient died suddenly postoperatively, and a second due to a fatal atrio-ventricular block. A third patient died following a subdural bleed. Three patients required a pacemaker before hospital discharge. The overall patient survival was 97 ± 2.26% at 1 year. Echocardiographic results preoperative, 8 days postoperative and 12 months after surgery showed mean transvalvular gradients of 50.6 ± 15.3, 15.6 ± 5.2 and 11.5 ± 3.8 mm Hg, respectively, and mean left ventricular ejection fractions of 37.9 ± 10.2%, 44 ± 15.2% and 53.6 ± 10.4%. Effective orifice area index for valve sizes 19, 21, 23, 25 and 27 were 0.91 ± 0.08, 0.97 ± 0.1, 1.08 ± 0.07, 1.53 ± 0.12 and 1.57 ± 0.1cm(2)m(-2), respectively. There were three early non-structural dysfunctions (grade 1) of regurgitation, which remained stable at 12 months. Freedom SOLO valve has very good early- and intermediate-term results. Short implantation times and its haemodynamic performances, particularly in small diameters, allow us to use it by first intention in older and often sicker patients. These results must be confirmed by long-term outcomes.

Preparation and biological properties of a novel composite scaffold of nano-hydroxyapatite/chitosan/carboxymethyl cellulose for bone tissue engineering

In this study, we report the physico-chemical and biological properties of a novel biodegradable composite scaffold made of nano-hydroxyapatite and natural derived polymers of chitosan and carboxymethyl cellulose, namely, n-HA/CS/CMC, which was prepared by freeze-drying method. The physico-chemical properties of n-HA/CS/CMC scaffold were tested by infrared absorption spectra (IR), transmission electron microscope(TEM), scanning electron microscope(SEM), universal material testing machine and phosphate buffer solution (PBS) soaking experiment. Besides, the biological properties were evaluated by MG63 cells and Mesenchymal stem cells (MSCs) culture experiment in vitro and a short period implantation study in vivo. The results show that the composite scaffold is mainly formed through the ionic crossing-linking of the two polyions between CS and CMC, and n-HA is incorporated into the polyelectrolyte matrix of CS-CMC without agglomeration, which endows the scaffold with good physico-chemical properties such as highly interconnected porous structure, high compressive strength and good structural stability and degradation. More important, the results of cells attached, proliferated on the scaffold indicate that the scaffold is non-toxic and has good cell biocompatibility, and the results of implantation experiment in vivo further confirm that the scaffold has good tissue biocompatibility. All the above results suggest that the novel degradable n-HA/CS/CMC composite scaffold has a great potential to be used as bone tissue engineering material.

Implante de stent não-valvado na via de saída do ventrículo direito: forma simples e efetiva de retardar nova intervenção cirúrgica

ABSTRACT Non-Valved Stent Implantation in Right VentricleOutflow Tract: a Simple Way to PostponeNew Surgical Intervention Background: Right ventricle outflow tract (RVOT) recons-truction is frequently used to repair cardiac malforma-tions. However, the lifetime of these conduits is short andstent implantation is a good option to relieve obstructedRVOT. The objective of this study is to report the experienceof a tertiary center with non-valved stent implantationand its short and medium term results. Methods: BetweenSeptember 1990 and January 2009, 11 late postoperativepatients were submitted to stent implantation due to RVOTobstruction. Mean age at the time of procedure was 12.5 ±8.3 years (1-28 years), and mean weight was 35 ± 20.9 kg(6-62 kg). Mean follow-up time was 12.5 ± 6 months (0-48months). Results: Mean systolic right ventricular pressuresdecreased from 99 ± 23 mmHg before to 57 ± 12 mmHg(p < 0.001) after stent implantation. At echocardiogram,RV to PA gradient decreased from 69 ± 19 mmHg to 33 ±20 mmHg (p < 0.01). Forty percent of the patients requiredpercutaneous or surgical reintervention during a meantime of 22 months after the procedure. There was onecase of stent fracture, relieved with the implantation ofanother stent, one case of failure, and one death notrelated to the procedure.