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At least 253 records · Page 14Linked to original sources
PubMed1991

[Preliminary evaluation of the usefulness of vascular prostheses Protegraft DV 1900 manufactured by B. Braun Melsungen AG].

The authors carried out preliminary clinical evaluation of usefulness of the knitted vascular prostheses Protegraft DV 1900 of B. Braun Melsungen AG's firm. 10 prostheses of that firm were used for investigation implanting biforked protheses to six patients and single prostheses to four patients. Such qualities were taken into account: their behaviour in the operation field during the operation so blood percolating through the wall, shredding of the edges, passing of the suture through the prostheses as well as wall rigor after blood coagulation. It was observed that the vascular prostheses Protegraft DV 1900 together with the advantages ascribed until now to prostheses from woven materials and, first of all, a very short period of bleeding through the wall after releasing the clip.

Adult↗
PubMedDate not supplied

[The interactions between metal stapes prostheses and high-intensity magnetic fields during magnetic resonance tomography].

The ever-increasing use of magnetic resonance tomography (MR) as an investigation mean has created a new interest in the biological effects of magnetic fields (MF) and in finding protective measures to be taken in their event. At the moment, use of MR is contraindicated in the presence of pacemakers, vascular clips, liquoral shunts and orthopedic prostheses, all of which may be dislocated by the MF created by MR or may interact with the MF itself creating distorted or falsified images. The aim of our study was to verify if metallic stapedectomy prostheses are dislocated by the MF and if they produce enough interference to falsify MR images. Five types of metallic stapedial prostheses exposed to a MF of 0.5T were studied. We may conclude from our results that MR does not create any otological risks for patients with these prostheses in that none of them were dislocated during exposure. However, all the prostheses studied did instead bring about alterations in the MF and the MR image to varying degrees. In some cases (Robinson) there was notable image distortion, while in others (Schuknecht wire teflon and platinum piston) the distortion was practically negligible. It is our opinion, however, that even if the image distortion does not interfere with routine MR, use of prostheses made of materials not affected by MF are advisable in view of an eventual development of visualization of the labyrinth and intratemporal facial nerve portion with MR.

Artifacts↗
PubMed1991

[Cephalic prosthesis for fractures of the femoral neck (702 cases). Comparative results of simple and intermediate cephalic prostheses].

The authors are presenting a retrospective study of the long time results of 702 femoral cephalic endoprostheses, 451 unipolar and 251 bipolar. The mean age of the patients at the moment of intervention was 80 years, the operation was done in the majority of the cases for a fracture of the femoral neck. The average follow-up was 33 months for the unipolar, and 24 months for the bipolar prostheses. The rate of reoperations was similar in both series, but the rate of luxations was slightly lower for the unipolar prostheses. 82 patients (out of 120 surviving) have been controlled with an average follow-up of 6.5 and 4.5 years. The unipolar prostheses had a lower average New Mayo Hip Score (58.5 vs. 68.2). Radiologically, there were 7 acetabular protrusions in the group of unipolar prostheses and none in the other group. If both types of prostheses have their place in surgery of the hip, the authors recommend to implant bipolar prostheses in younger and more active patients, where a survival of many years is expected.

Actuarial Analysis↗
PubMed1990

Long-term survivorship analysis of cruciate-sparing versus cruciate-sacrificing knee prostheses using meniscal bearings.

A comprehensive, interchangeable, low-contact-stress, mobile-bearing knee prosthesis system was developed and used over a 12-year period with both cemented and cementless fixation. Individual components of the system included a bicruciate-retaining meniscal bearing, a posterior cruciate-retaining meniscal bearing, and a cruciate-sacrificing, rotating-platform tibial component mated to the same femoral and rotating patellar components. Survivorship analysis of each implant type was performed to identify specific failure modes and trends for long-term survival of the implants in a wide variety of primary knee arthroplasties. Clinically, there were 46 prostheses of the bicruciate type followed for up to 12 years, 57 prostheses of the posterior-cruciate type followed for up to six years, and 108 prostheses of the rotating-platform type followed for up to ten years. All knees in this study had rotating-bearing patellar prostheses. Cumulative survivorship analysis using an end point of implant revision or a poor knee score revealed a small early failure rate of each implant in the first three years, associated with technical positioning or undersizing errors. This study indicates a predictable long-term survival of both cruciate-retaining and cruciate-sacrificing mobile-bearing knee prostheses as well as rotating-bearing patellar prostheses when used in primary knee arthroplasties that minimized technical errors of insertion.

Adult↗
PubMed1989

[Follow-up of patients with valve prostheses using one- and two-dimensional echocardiography].

The authors examined by one- and two-dimensional echocardiography 28 patients with valvular prostheses, divided into groups, depending on the type and position of the prosthesis. They assessed the excursions of the disc or ball, the speed of opening and closure, time intervals A2-MVO and S1-AVO and the size of the left cardiac compartments. They investigated the occurrence of paradoxical movements of the interventricular septum, the diastolic wave in mitral prostheses and the flutter of the anterior cusp of the mitral valve in aortic prostheses. The results of these observations were confronted with data in the literature. In the investigated group of patients no pathological findings were detected. In mitral ball prostheses greater excursions were recorded than in eccentric disc-shaped prostheses. The closing speed was always greater than the opening speed. The A2-MVO interval was approximately double, as compared with S1-AVO. It was found that the paradoxical movement of the interventricular septum persists longer than reported in the literature. One-dimensional echophonocardiography and 2-D echocardiography retains its importance for the follow-up of patients with valvular prostheses.

Adult↗
PubMed1987

[New textile vascular prostheses made of polymer composition materials].

Functional properties of blood vessel prostheses to large degree depend on the longitudinal elasticity of their walls. Theoretical foundations for designing the physico-chemical properties of prostheses walls were worked out, and special methods and measuring apparatuses. New types of vascular textile prostheses make it possible to model biological tissues. The prostheses walls are a composition of polymers of several types of threads differing to large degree in their elasticity. Comparative theoretical and experimental studies on natural blood vessels, blood vessel prostheses (of traditional threads) and new textile prostheses showed that the last mentioned, as far as their elasticity in concerned, are most close to the requirements and that they have good functional properties.

Animals↗
PubMed1985

[Long-term antithrombotic treatment in patients with valve prostheses. Practical management and complications].

The cumulative annual risk of thrombo-embolic and haemorrhagic complications due to anticoagulants in patients with mechanical prostheses is in the order of 3 to 9 p. cent for mitral prostheses and mitral and aortic prostheses and 2 to 5 p. cent for aortic prostheses. Anticoagulant drugs should be chosen in terms of the type and the site of the implanted prosthesis and the coefficient of the thrombo-embolic and haemorrhagic risk of each subject. In patients with mechanical prostheses, the most effective prevention of the thrombo-embolic risk is ensured by the anti-vitamin K drugs associated with dipyridamole, with a low haemorrhagic risk if the treatment is correctly controlled. In patients with bioprostheses, the anticoagulant treatment (anti-vitamin K or anti-platelet drugs) should be maintained for three to six months after the operation; the anti-vitamin K drugs should not be prolonged indefinitely, except in patients at high risk of thrombo-embolism (atrial fibrillation with a very dilated left auricle, in particular). The management of a pregnant woman with a valve prosthesis and the problems of patients with prostheses undergoing extracardiac or dental operations or invasive investigations are still open to discussion.

Anticoagulants↗
PubMed1985

[Clinical studies of Gore-Tex vascular prostheses. A review of the literature].

Reconstruction of arterial and venous vessels by means of polyester and teflon vascular prostheses gives unsatisfactory distant results. Three-year long observations show that only 50% are satisfactory. The best results are achieved when autogenous veins are grafted. It is estimated, however, that in 15-30% of cases the veins are useless as prosthetic material because of various pathological changes. New types of vascular prostheses have to be searched for, such that would meet all requirements. In the end of the 1970 the Gore Firm worked out a unique technological process of making vascular prostheses of pure, distensible or reinforced polytetrafluoroethylene, porous in structure. In 1970 such prostheses, named Gore-Tex, were subjected to experimental studies. The present paper discusses first publications on the prostheses, the publications included ample statistic material and discussed perspectives in vascular surgery that the new type of vascular prostheses opens.

Aged↗
PubMed1983

Dilation of knitted Dacron aortic prostheses and anastomotic false aneurysms: etiologic considerations.

Five patients with knitted Dacron aortic bifurcation prostheses developed prosthetic dilation and anastomotic false aneurysms. The interval between placement of prostheses and secondary presentation ranged from 4 to 10 years. Three patients presented with femoral false aneurysms (one ruptured) and two presented with aortic false aneurysms (one ruptured). In all cases, anastomotic sutures remained intact on the prosthesis and there was no evidence of infection. The mean (+/- SEM) increase in diameter of prostheses was 85.7 +/- 19.1% (range 76% to 137%). Dilated prostheses were removed in four cases and were tested for tensile strength and studied with scanning electron microscopy. These were compared to normal, nondilated knitted Dacron prosthetic fabric from the same manufacturer. There was no loss of breaking strength in dilated prostheses. Furthermore, on examination with scanning electron microscopy, there was no evidence of degeneration or fracturing of individual Dacron filaments. However, dilated prostheses were found to have a greatly expanded knit. The distance between loops was significantly increased and the number of fibers per 1000 microns was significantly less in comparison to normal knitted Dacron fabric. These studies confirm an association between prosthetic dilation and false aneurysm formation. Further, they suggest that the cause of prosthetic dilation is loss of compactness of the knit not associated with intrinsic Dacron fiber deterioration. A fabrication defect is most likely responsible.

Aged↗
PubMed1983

Urinary cobalt levels in patients with porous Austin-Moore prostheses.

Austin-Moore prostheses with a porous surface have been used recently to improve stabilization in total joint arthroplasty. However, these prostheses expose tissue directly to greater metallic surface area than previous nonporous designs. Cobalt levels were measured in the urine of patients who had received porous and nonporous prostheses, to assess any increased risk of metal toxicity posed by the porous design. Although a higher mean urinary cobalt concentration was found for patients with porous prostheses, the absolute levels were comparable with those of patients with nonporous prostheses. The prostheses with a porous surface appear to pose no significant added risk of metal toxicity as compared with the nonporous design.

Cobalt↗
PubMed1978

Basic studies on autogenized and lysophilized vascular prostheses.

In an effort to improve vascular prostheses, basic studies on tissue-alloplastic prostheses according to a new conception were performed. A medical polyester yarn was used for the construction of three types of prostheses with different mesh and high porosity. The prostheses were autogenized on silicon rods and then lyophilized, resulting in their full intraoperative impermeability, but high biological permeability and antithrombogenicity. Vascular prostheses of this type fulfill many of the requirements of a so-called ideal prosthesis. Analysis of the test examinations provides a basis for elaborating principles for the preparation and production of new tissue-alloplastic prostheses for clinical purposes.

Bacterial Infections↗
PubMed1981

[Usefulness of Dallon prostheses for blood vessel reconstruction].

Experimental and clinical results of the application of Dallon prostheses in vascular surgery are presented. Dallon prostheses are produced in the Medical Materials Department of the Research Development Centre of the Knitting Industry in łódź. They are contained in disposable radially sterilized wrappings. The experiments were performed on 17 mongrel dogs and the process of healing in was observed after three and six months. The process was similar to the healing in of other porous, synthetic prostheses. In 37 patients operated because of the artheromasia bypasses or vascular flaps of Dallon prostheses were implanted. The results of experimental and clinical research proved that the radially sterilized Dallon prostheses have similar properties like the prostheses produced be well known foreign firms, and are very useful in arterial reconstruction.

Aged↗
PubMed1980

Results of knee replacement with the Walldius and geometric prostheses. A comparative study.

Sixty-two knees that were replaced with Walldius prostheses and twenty-five knees with geometric replacements were studied prospectively. The follow-up ranged from twenty-four to 162 months (average, seventy-four months) for the knees with the Walldius prostheses and from twenty-four to seventy-five months (average, forty-seven months) for those with the geometric prostheses. Using a 100-point clinical rating scale, the knees of patients who underwent Walldius replacement improved from their preoperative status by an average of 33 points (from 44 to 77 points) and those with geometric prostheses, an average of 24 points (from 54 to 78 points). Twelve patients with twenty Walldius prostheses were followed for more than 100 months (average, 127 months). The greater average improvement (36 points) in this group was due primarily to the absence of any major complications. Six patients underwent replacement of one knee with a Walldius prosthesis and one knee with a geometric implant. Although the ratings for the two knees were similar in each patient, four patients preferred the Walldius implant; one, the geometric replacement; and one had no preference. Significant technical errors or complications (defined as those affecting the end result) occurred in 8 per cent of the knees with Walldius implants and in 12 per cent of the knees in the geometric group. There were two late infections in each group. One Walldius prosthesis was removed and the knee was fused. The other three prostheses (one Walldius and two geometric) associated with infection were salvaged.

Adolescent↗
PubMed1995

Enumeration of human knee prostheses--an overview.

Very often clinicians prescribe a limited number or only one type of knee mechanism because it has been found reliable or perhaps specific information on the range and variety of all available mechanisms has not been on hand. The clinician rarely has the opportunity to see all the mechanisms in a common perspective to compare the relative merits of one mechanisms with another. An attempt has been made to enumerate the available human knee-prostheses, both implants and external prostheses, according to their motion. An historical development of knee prosthesis is discussed. A classification procedure is developed for both internal and external prostheses based on their primary functions. The two major classifications in either of these prostheses are monocentric and polycentric mechanisms. A mechanism whose center of rotation does not change through out the range of motion is considered as monocentric mechanism and a mechanism whose center of rotation changes during its operation is considered as polycentric mechanism. The implants are categorized as hinged and non-hinged knee joints. The external prostheses are further classified based on certain primary functions like control in swing phase and/or in stance phase and in extension. The hierarchical classification scheme will benefit kinematicians and designers to analyze the available mechanisms and make necessary improvements. This will also provide a ready-reference to the prosthetists in selecting the best-fit prosthesis from a large family of prostheses.

Artificial Limbs↗
PubMed1996

Long-term results with Hydroflex and Dynaflex penile prostheses: device survival comparison to multicomponent inflatables.

PURPOSE: We compared our experience with self-contained inflatable and multicomponent prostheses during similar intervals. MATERIALS AND METHODS: We followed 295 patients with self-contained prostheses and 1,026 with multicomponent inflatable devices for up to 8 years. Revision rates for mechanical failure, infection or patient dissatisfaction were statistically analyzed. RESULTS: Multicomponent inflatable prostheses were superior with regard to mechanical reliability and patient satisfaction, with no differences in rate of infection. Self-contained prostheses were best replaced with the AMS 700CX device, thus avoiding aneurysm. CONCLUSIONS: Self-contained inflatable prostheses may be of limited value for the treatment of impotence. The AMS 700CX is the device of choice for replacement of explanted self-contained prostheses.

Follow-Up Studies↗
PubMed1995

Incorporation of fibronectin-impregnated vascular prostheses in the pig. Microscope study.

An interface near the endothelial extracellular matrix is necessary to augment and maintain endothelial cell attachment. The use of plasma lectins constitutes one of the present lines of research designed to improve this interface. We studied the incorporation of 2 series of arterial prostheses with a diameter of 4 mm and a mean length of 9 cm. They were implanted in the carotid arteries of adult Europig minipigs. Prostheses were of two types: polytetrafluoro-ethylene (PTFE) and knitted Dacron. Two series of 12 pigs each were used. One was explanted at 3 months and the other at six. Each pig was grafted with one prosthesis impregnated with the plasma components of diluted Fibrogel and one non-impregnated prosthesis which served as control. The explanted prostheses and adjacent parts of the carotid were prepared for light or scanning electron microscopy. Proximal, median and distal segments were cut and embedded in resin. Collagen distribution was revealed by Milligan's trichrome stain, and fibrin distribution by Picro-Mallory staining. Macroscopic examination showed discrete periprosthetic adhesion for impregnated prostheses and complete adhesion for non-impregnated prostheses. Scanning electron microscopy revealed a median endothelial cell coating on impregnated grafts whereas the only endothelial cells on non-impregnated grafts, were perianastomotic. On impregnated grafts, Milligan's trichrome staining revealed an even collagen distribution. The walls of non-impregnated grafts exhibited capillary cell infiltrations with breaches in the outer structures. In impregnated prostheses, the absence of such breaches enabled us to postulate that their incorporation was better than that of the non-impregnated grafts. The minipig model was hard to handle because of the aggressiveness engendered by restricted feeding designed to limit weight increases. In general, however, we may justifiably conclude that in this model, the use of plasma lectins improved prosthetic incorporation.

Animals↗
PubMed1996

A hemodynamic comparison of Omniscience and Medtronic Hall aortic prostheses.

BACKGROUND AND AIMS OF THE STUDY: Preliminary reports have suggested hemodynamic disparities between single leaflet tilting disc prostheses. We tested the hypothesis that similarities in prosthetic design may not necessarily indicate hemodynamic equivalence. MATERIALS AND METHODS: In a retrospective analysis, we compared the functional characteristics of two single tilting disc (Omniscience and Medtronic Hall) prostheses implanted in the aortic position in 30 patients matched for valve size and left ventricular systolic function. RESULTS: Echocardiographic and Doppler analysis blinded to patient and valve type indicated similar quantitative left ventricular ejection fractions (64% +/- 6% for both) and cardiac outputs (4.8 +/- 1.2 vs. 4.6 +/- 1.2 l/min, p = 0.65) in the Onmiscience and Medtronic Hall groups, respectively. Transprosthetic instantaneous peak gradients were greater for Omniscience than for Medtronic Hall valves (44 +/- 8 vs. 35 +/- 11 mmHg, p < or = 0.02), as were the mean values (24 +/- 6 vs. 18 +/- 6 mmHg, p = 0.01). Even when 21 and 23 mm prostheses were analyzed separately to allow for unequal sewing ring diameters in the smallest valve sizes (Omniscience = 19 mm, Medtronic Hall = 20 mm), higher gradients were noted in the Omniscience prostheses. Effective orifice areas were smaller in the Omniscience than Medtronic Hall prostheses whether data from all prostheses (0.92 +/- 0.11 cm2 vs. 1.09 +/- 0.18 cm2, p < or = 0.05), or only data from 21 and 23 mm valves (0.94 +/- 0.11 cm2 vs. 1.10 +/- 0.18 cm2, p < 0.05) were included. Similarly, the dimensionless obstructive index, a parameter independent of left ventricular flow and annular size, was reduced in the Omniscience valves, indicating greater obstruction, whether all valves (0.31 +/- 0.04 vs. 0.36 +/- 0.07, p < or = 0.01) or only 21 and 23 mm valves (0.31 +/- 0.04 vs. 0.36 +/- .04, p < 0.001) were analyzed. CONCLUSION: Despite prosthetic design similarities, resting hemodynamic assessment indicates greater stenosis in Omniscience than Medtronic Hall valves when placed in the aortic position. The long term effects of these differences in terms of ventricular diastolic and systolic function and mass regression requires further evaluation.

Aortic Valve Insufficiency↗
PubMedDate not supplied

The echo Doppler study of mitral and aortic prostheses function.

Doppler echography is now the most accurate noninvasive method for studying valvular prostheses, but the values considered to prove a normal function are still controversial. We studied by echo Doppler 95 valvular mechanical (M) and biological (B) prostheses, in mitral (Mi) and aortic (Ao) position in patients without clinical signs of prosthetic dysfunction. The data obtained for Ao prostheses (maximal transprosthetic gradient (MxG): M-20.47 mmHg, B-7.95 mmHg; mean transprosthetic gradient (MG): M-7.98 mmHg, B-3.9 mmHg) are in agreement or even better than literature data. For Mi prostheses the prosthetic area (PA) and pressure half time (PHT) values are in normal limits but the MG (M-5.087 mmHg, B-5.9 mmHg) is slightly superior to the data reported in the literature. Proving the value of echo Doppler for the study of valvular prostheses our results suggest to adopt larger limits of normality for mitral prostheses. They also sustain the necessity of a first Doppler examination before the patient is discharged from the hospital after valvular replacement.

Adult↗