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At least 415 records · Page 23Linked to original sources
PubMed1997

Survey of above knee (A/K) prostheses currently used in the Chugoku-Shikoku district of Japan.

To determine the extent to which recent advances in biomechanical technology have been implemented and to evaluate these new technologies, 84 unilateral above knee (A/K) amputees and their prostheses were surveyed in the Chugoku-Shikoku district of Japan, especially in regard to the types, sockets and components of A/K prostheses currently in use. Background factors such as age and sex of the A/K amputees and the period after amputation were also surveyed. Of the 84 amputees surveyed, 74 (88.1%) were over 40 years old and 40 (47.6%) were over 60 years old. There were 10 women (11.9%) and 74 men (88.1%). The period after amputation was under 25 years in 58 (69.0%) cases. Regarding the type of A/K prostheses, one-third of the prostheses was of the exoskeletal type and two-thirds were of the endoskeletal type. Although the endoskeletal type is becoming more popular recently, elderly A/K amputees tend to use the exoskeletal type. Thirty-one (36.9%) had plug-fit sockets which are preferable for those who follow the Japanese practice of sitting on the floor, especially for elderly amputees. Thirty-seven (44.0%) had a lock-knee, 27 (73.0%) of which were used by amputees over 60 years old. Seventy-three (86.9%) had a single-axis ankle which is generally considered to be the most stable ankle. Thus, the most common combination of prosthetic components for elderly A/K amputees was the plug-fit socket, lock-knee joint and single-axis ankle.

Adult↗
PubMedDate not supplied

Fixation of auricular prostheses by osseointegrated implants.

Placement of enosseous implants in the temporal bone may overcome the apparent disadvantages of skin adhesives and skinpockets for the fixation of auricular prostheses. The surgical procedure for placement of implants in the temporal bone and the results obtained in eight patients wearing implant-supported auricular prostheses are described. From the results of this study, it is obvious that osseointegrated implants have great advantages compared with skin adhesives and skinpockets to rehabilitate patients suffering from auricular defects. The major achievement of implant-supported auricular prostheses is the patients' increased comfort and confidence wearing these types of prostheses.

Adult↗
PubMed2000

Radiotherapy prostheses.

The orofacial region performs the essential functions of mastication and speech, as well as that of appearance, which for better or worse evokes an instant and instinctive response in other people. In this region, tissue loss caused by surgical resection of a malignant tumor has a tremendous negative impact on the patient's quality of life, with deep mental and psychological repercussions. Therefore, from the standpoint of preserving form and function, radiotherapy has a major role to play in the treatment of malignant tumors in the orofacial region. That said, important organs, such as sensory organs, are present in close proximity to each other in this small region. During the irradiation process, therefore, it is important to ensure that the lesion is sufficiently irradiated while simultaneously protecting the surrounding normal tissue. In certain cases of radiotherapy of malignant tumors of the orofacial region, the use of radiotherapy prostheses can help to satisfy a basic principle of radiotherapy: that of delivering a lethal dose to the tumor while minimizing irradiation to normal tissue. In recent years, medical and dental experts have taken a team approach to creating and employing a variety of radiotherapy prostheses, working towards improving the treatment record for malignant tumors as well as reducing complications in surrounding normal tissue. As a result, patients treated with radiotherapy prostheses are now able to receive post-radiotherapy prosthodontic treatment in a dramatically safer and more rapid manner. It is clear that radiotherapy prostheses contribute significantly to the improvement of these patients' quality of life.

Brachytherapy↗
PubMedDate not supplied

[Self-expandable prostheses for palliation of gastric cancer: report of four cases].

Self-expandable prostheses have gained in popularity for palliation tumors of the gastrointestinal tract. We present four cases of patients with gastric adenocarcinoma who were palliated by self-expandable metallic prostheses. Two patients had undergone total gastrectomy with esophago-jejunal anastomosis. In one there was recurrent cancer in the anastomosis and the other had non-malignant stenosis. The remaining two patients had unresectable tumors. Correct placement of prostheses was possible in all cases; however, maintenance of adequate hydration and acceptable nutritional status per orem was possible only in three of four patients. In all cases there was temporary slight pain, in one, slight hemorrhage, and in one the prosthesis migrated and it was necessary to withdraw it surgically. Although these are only a few cases, we can say that self-expandable prostheses are a promising alternative to palliate gastric cancer.

Adenocarcinoma↗
PubMedDate not supplied

[Biological and synthetic prostheses in gynecologic microsurgery].

Biological prostheses of human umbilical vein and synthetic prostheses of ePTFE were comparatively studied in the microsurgical anastomosis of the uterine horns in twenty rats. Patency rate after 30 days was 60% for umbilical vein and 75% for the ePTFE prostheses. Gross and histological examination of umbilical vein graft specimens showed minimal alteration with a smooth intimal surface. On the contrary tissue covering the inner surface from the adjacent ends of the uterine horns was noted in ePTFE prostheses.

Animals↗
PubMed1990

Effects of age and prosthesis material on in vitro cartilage retention of laryngoplasty prostheses in horses.

Cartilage retention strengths of laryngoplasty prostheses were compared in larynges of 2-, 3-, and 4-year-old horses, using doubled polyester and expanded polytetrafluoroethylene prostheses. Bilateral laryngoplasties were performed on each of 15 (seven 2-year-old, two 3-year-old, and six 4-year-old) larynges, which were collected at an abbatoir. Prostheses were secured to a mechanical testing machine, and tension causing arytenoid cartilage abduction was applied, until total failure of the cartilage or prosthesis resulted. Tension caused cricoid cartilage failure in 1 specimen, and muscular process cartilage failure in the remainder. There was no significant effect of age, prosthetic material, or side of prosthesis placement on cartilage retention of the prostheses. Additionally, frequency of multiple load-displacement peaks, indicating partial muscular process failure, was not affected by age or prosthetic material variables.

Age Factors↗
PubMed1980

[Polypropylene-polyester prostheses. Experimental studies].

Polypropylene-polyester prostheses invented by the Research and Development Center of the Textile Industry in łódź are composed of two knitted polyester layers with perpendicular columns arrangement laminated by polypropylene. The prostheses were implanted in 10 pigs into the sternum and shoulder blade, the abdominal wall and peritoneal cavity. The autopsies of the animals were made 90 to 180 days after the operation. Both in bone and soft tissues, the prostheses healed up without local or general complications. The results obtained in surgical post-operative, macroscopic and microscopic examinations prove that the polypropylene-polyester prostheses fulfill the basic conditions for biomaterials. The different moulders of these materials may be used as temporary or permanent implants.

Animals↗
PubMed1994

Experimental study of the acoustic properties of incus replacement prostheses in a human temporal bone model.

Many middle ear prostheses are available for reconstruction of a missing or damaged incus. Little is known of the relative acoustic performance of these prostheses in vitro and the parameters (mass, shape, tension, angulation, area of head) that modify this performance. This report describes experiments in a human temporal bone model comparing the effect on stapes displacement of six commercially available incus replacement prostheses (IRP). Measurements were performed using a laser Doppler vibrometer before and after incus removal and IRP placement between the tympanic membrane (TM) and stapes head. In addition, experiments were performed on the effect of increasing prosthesis mass, varying the tension between TM and stapes head, changing the surface area in contact with the TM, and comparing different TM contact sites. All prostheses tested showed reasonable acoustic performance compared to the baseline condition. Optimum tension between the TM and stapes head produced the best overall sound transmission. The mid-malleus and umbo locations were the best malleus contact sites; however, the posterior TM contact site also worked well. Increased mass improved low frequency transmission and impaired higher frequency transmission, whereas a larger contact area with the TM contributed to increased gain in the mid frequencies.

Aged↗
PubMed1987

A rapid in vitro test of the in vivo healing potential of vascular prostheses.

An in vitro method for comparing the penetration of bovine fibroblasts seeded on the external surface of porous vascular prostheses was devised. The effects of water porosity reduction and differing manufacturing constructions (warp-knit Dacron, woven Dacron and polytetrafluoroethylene) on the ability of the bovine fibroblasts to penetrate transmurally was investigated. Of the warp-knit external-veloured Dacron prostheses, the highest porosity 140-denier prototype had the highest luminal surface cell count and the lowest porosty 280-denier prototype the lowest luminal surface cell count. The intermediate prototypes had values between these two extremes. The woven Dacron prostheses, which were of even lower porosity but with a much thinner wall, had cell counts midway between the 140-denier and the 280-denier prototypes. The microporous polytetrafluoroethylene prostheses did not allow fibroblast penetration despite adherence of cells to the outer surface. These findings agree with in vivo healing studies of the same materials in the descending thoracic aorta of the dog, demonstrating that this rapid in vitro assay method can help predict the healing potential of a vascular prosthesis.

Animals↗
PubMed2005

Ultrastructural analysis of guided nerve regeneration using progesterone- and pregnenolone-loaded chitosan prostheses.

Recently, numerous guide chambers for the treatment of injured nerves made up of different biomaterials have been designed, capable of hosting living cells or carrying neurotrophic or neuroactive substances to be directly released to the injured tissue. In this study, chitosan prostheses containing neurosteroids (progesterone and pregnenolone) were used for bridging a 10-mm gap in the rabbit facial nerve. Gas chromatography was used to quantify neurosteroid content in the prostheses prior to and after subcutaneous implantation at different periods of up to 60 days. The regeneration of the nerve fibers were evaluated at 15 and 45 days after axotomy by means of ultrastructural morphometric analysis. Different nerve fibers regenerative patterns were seen depending the groups studied and the analyzed stages. At 15 days after axotomy, the newly regenerating tissue revealed Schwann cells holding nonmyelinated nerve fiber bundles in an incipient and organized regenerative pattern. At 45 days, the regenerating tissue showed myelinated nerve fibers of different sizes, shapes, and myelin sheath thickness. Although the regeneration of the nerve fibers under neurosteroid treatment showed statistically significant differences in comparison with vehicle regenerated tissue, progesterone-loaded chitosan prostheses produced the best guided nerve regeneration response. These findings indicate that chitosan prostheses allowed regeneration of nerve fibers in their lumen, and when containing neurosteroids produced a faster guided nerve regeneration acting as a long-lasting release delivery vehicle.

Animals↗
PubMed1995

Elastase activity, uninhibited by alpha 1-antitrypsin, in the periprosthetic connective matrix around loose total hip prostheses.

To clarify the proteolytic cascade in the loosening of total hip prostheses, the presence, tissue localization, and content of the serine proteinase, elastase, and its endogenous inhibitor, alpha 1-antitrypsin, were studied in periprosthetic tissues around 12 loose hip prostheses by immunohistochemistry, spectrophotometric enzyme assay, and immunoblot analysis, and the results were compared with those in control synovial tissue samples from eight knees. Increased numbers of elastase-immunoreactive cells and elevated elastase activity, inhibited by the addition of native alpha 1-antitrypsin, were observed both in the interface tissues between the bone and implants and in the pseudocapsular tissues from around loose hip prostheses. Elevated elastase activity, uninhibited by alpha 1-antitrypsin in situ and inhibited by the addition of native inhibitor, suggests a proteinase-inhibitor imbalance that contributes to the weakening of periprosthetic tissues and thus causes the loosening of hip prostheses.

Adult↗
PubMed1983

Evaluation of the patency rate of fibrous microvascular polyurethane prostheses after implantation in the rat aorta.

Two types of fibrous polyurethane prostheses with different compliances were implanted into the rat aorta with interrupted sutures and a running suture line. Excluding two technical failures, one unexplained death, and three infected prostheses, both groups (n = 21) showed a patency rate of 100%, up to 6 months after implantation. Rapid reendothelialisation occurred, and a stable neo-intima was formed. Compliance of the prostheses, as well as the suture technique used, has proven to be an unimportant factor in the rat aorta model, probably due to the low magnitude of the pulsations of the rat aorta. The experience of the surgeon with microsurgical techniques seems to be an underestimated factor in determining patency rates of microvascular prostheses.

Animals↗
PubMed1985

History of (micro) vascular surgery and the development of small-caliber blood vessel prostheses (with some notes on patency rates and re-endothelialization).

The historical development of vascular surgery is reviewed from ancient times (Ruphus of Ephesus, Aëtius of Amida) to recent developments (sutured anastomosis by Carrel). Attempts to anastomose blood vessels by means of nonsuturing technique, using a ring or short tube of diverse materials called prostheses, were undertaken at the start of this century and continued until shortly after World War II. With the advent of modern polymeric materials, prostheses of different types, sizes, structures, and fabrics have been used to substitute for blood vessels, both experimentally and clinically. Recently, blood vessel prostheses with small (1-1.5 mm) internal diameters became available and have been implanted experimentally. Patency rates, biophysical and structural properties, the re-endothelialization and the neointima formation of several types of microvascular prostheses are briefly reviewed.

Animals↗
PubMed1987

Determination of the patency of vascular prostheses implanted in the rat aorta by means of ultrasonic blood-flow measurements.

Patency of vascular prostheses implanted in the rat aorta is usually confirmed by reoperation and inspection of the distal stump of the aorta for pulsations. Repeated reoperation on rats included in long-term investigations is not possible because of the increasing formation of scar tissue and adhesions at the site of the distal aorta. Consequently, noninvasive ultrasonic Doppler measurement was investigated to determine whether this method could provide accurate information about the patency of an implanted prosthesis. A total of 37 rats with 10-cm-long prostheses implanted in the aorta (groups C nonsupported prostheses, n = 12; and D supported prostheses, n = 25), eight normal nonoperated controls (group A), and three rats with a ligated aorta (negative controls, group B) were studied over a period of 12 weeks. The Dopplerrecordings obtained in the normal animals served as controls for the recordings of rats with an implanted prosthesis. A prosthesis was considered patent if the Dopplermeasurements obtained from the femoral artery resembled that of the normal pattern. In seven cases a prosthesis was suspected to be occluded since the Dopplermeasurements resembled those obtained after aortic ligation. Autopsy confirmed the Dopplermeasurements in all cases. No Dopplermeasurements returned to normal in the femoral artery in the aorta-ligated rats even after longer periods post-operation. It is concluded that Dopplermeasurements can accurately provide information about the patency of a vascular prosthesis implanted in the rat aorta.

Animals↗
PubMed1995

Influence of luminal pore size on the patency rate and endothelialization of polymeric microvenous prostheses.

In microvenous prosthetic surgery a continuous search for better patency rates is necessary to enable a clinical application. In this search for better patencies, modifications in the wall structure are being made. Directions found in the literature suggest that pore size plays an important role in achieving better patencies. Thus far, no study has been conducted to evaluate the influence of pore size on the patency rate of polyurethane microvenous prostheses. Since polyurethane is known to yield good patency rates, we conducted this study in which we compared different luminal pore sizes with regard to patency. Pore size varied from 0.6 to 20 microns in microvenous polyurethane-based prostheses (length 5-6 mm, internal diameter 1 mm). The results showed a favorable patency rate in the pore sizes larger than 5.0 microns (patency 75%) when compared to pore sizes smaller than 2.0 microns (patency 50%). This study demonstrates that microvenous polyurethane-based prostheses with a luminal pore size larger than 5.0 microns may yield better patency rates than prostheses with a luminal pore size smaller than 5.0 microns. Further studies are currently being performed to elucidate the very reasons for this effect.

Animals↗
PubMed1991

Cementless fixation of hip prostheses in dogs.

Fixation of smooth cementless femoral prostheses was studied in 16 dogs which were killed 2, 3 and 4 months after operation. Rotational stability, examined by hand, was good in 9 cases and all stable prostheses could be extracted. Five out of 6 dogs, who did not bear weight after the operation, had a stable prosthesis compared with 4 out of 10 who walked early. Histology showed close bone apposition in 4, tight fibrous encapsulation in 4 and lack of tissue apposition in 8 which were loose. Bone remodelling in radiographs reflected the histological appearances; narrow radiolucent spaces were associated with dense well organised fibrous tissue, and wide radiolucent spaces with loose connective tissue. Prostheses with stems which fill the femoral canal should improve the fixation of smooth cementless prostheses.

Animals↗
PubMed1995

Immunoscintigraphy with antigranulocyte monoclonal antibodies for the diagnosis of septic loosening of hip prostheses.

To determine the value of immunoscintigraphy (IS) with antigranulocyte monoclonal antibodies (Mab) in the diagnosis of subacute or chronic infection of hip prostheses, we prospectively studied 57 patients (23 women and 34 men; age 29-92 years, mean 72.7 years) sent to our institution in the past 6 years for clinical suspicion of septic loosening of a hip prosthesis. Nineteen patients had bilateral prostheses and one of them was studied twice. A total of 78 prostheses were examined. All patients had three-phase bone scans followed by IS with technetium-99m antigranulocyte Mab BW 250/183. Intervals between bone scans and IS varied from 2 days to 4 weeks. Final diagnosis was assessed by culture in 48 cases (articular puncture or intraoperative sampling) and by clinical follow-up of at least 8 months in 30 cases. Twelve prostheses were considered septic and 66 non-septic. The overall sensitivity and specificity were 92% and 64% respectively for bone scans, 67% and 75% for IS and 67% and 84% for both modalities together. In three cases, IS was doubtful and the final clinical diagnosis was negative for infection. False-positive results were observed in the presence of massive loosening of the prosthesis or in association with metaplastic peri-articular bone formation. In three of the four false-negative results, infection was proven only after enrichment of the culture, and the bacterium was Staphylococcus epidermidis. In 12/33 (36%) positive bone scans IS allowed the diagnosis of infection to be excluded. Overall accuracy of both modalities together was 81% and the negative predictive value was 93%, which compares favourably with the results reported for other non-invasive methods.

Aged↗
PubMed1999

[Endovascular prostheses: evolution, state-of-the-art and perspectives of a new technology].

The treatment of infrarenal aortic aneurysms by means of transluminally placed endovascular prostheses reflects significant progress in the field of vascular surgery. In the case of infrarenal aortic aneurysm it is possible to achieve technically successful implantation of such a prosthesis in well over 90 % of cases. The rate of clinical success, meaning lasting effective exclusion of the aortic aneurysm, cannot (yet) be definitively determined, since no long-term results are so far available. Secondary leaks are observed in at least 10 % of all patients, making a further therapy necessary (endorepair, conversion, embolization). Further development of endovascular prostheses will include optimization of the aortal/iliac attachment of the prostheses, a better configuration and the development of long-lasting materials that can be used for endovascular prostheses.

Aortic Aneurysm, Abdominal↗