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At least 721 records · Page 40Linked to original sources
PubMed2000

Age dependency of neointima formation on vascular prostheses in dogs.

Neointima formed quickly on vascular prostheses implanted in young dogs but not in aged dogs. Previously, we found that impeding neointima formation on vascular prostheses occurred more frequently in aged animals. From these observations, we hypothesized that neointima formation was age-dependent in dogs. To test the hypothesis, 26 fabric Dacron vascular prostheses were analyzed. Half of them were retrieved from aged dogs (more than 13 years old) while the other half were from young ones (less than 1 year old). The grafts were harvested at 8 weeks and 3 months after implantation. The graft surfaces were photographed and analyzed by computer for the ratio of the areas with and without thrombus. Light and scanning electron microscopic observation revealed that most of the thrombus-free areas were lined with endothelial cells. Then the endothelialized areas were calculated. Using data obtained from macroscopic, light microscopic, and scanning electron microscopic observations, the arithmetic means were calculated as the degree of neointima formation. In young animals, the degrees at 8 weeks and at 3 months were 89.1 +/- 8.5% (mean +/- SD) and 95.7 +/- 3.3%, respectively. In old animals, they were 27.9 +/- 5.9% and 31.5 +/- 6. 8%, respectively. From these results, we concluded that neointima formation was age-dependent in dogs.

Aging↗
PubMed2003

Study of the different types of actuators and mechanisms for upper limb prostheses.

Research in the area of actuators and mechanisms has shown steadily growing technological advances in externally activated upper limb prostheses. From among the actuators, advances include the use of piezoelectric materials, special metal alloys, polymers, and new motor applications, while the advances in mechanisms include mechanical designs based on the anatomy of the human hand and improvements in the way these components are combined. These efforts are aimed at meeting the need for anthropomorphic and functional prosthetic devices that enable patients to carry out basic daily tasks more easily and reduce the rejection rate of prostheses. This article technically discusses the several types of actuators and mechanisms, listing their main characteristics, applications, and advantages and disadvantages, and the current state of research in the area of rehabilitation of upper limb functions through the use of active prostheses. Comparisons of these devices are made with regard to the main criteria of construction and operation required to achieve optimal prosthetic performance.

Artificial Limbs↗
PubMed1999

Influence of crimping textile polyester vascular prostheses on the fluid flow kinetics. Groupe Européen de Recherche sur les Prothèses appliquées à la Chirurgie Vasculaire.

OBJECTIVES: to characterise the impact of the crimping of polyester prostheses on the fluid flow kinetics. DESIGN: an experimental in vitro study. MATERIALS AND METHODS: we investigated four models of polyester vascular prostheses in a continuous laminar flow circuit. The flow velocity was 80 ml/s for all experiments. We studied two fluids of different viscosity within the circuit. The speed of the particles was measured by a laser Doppler anemometer 2 to 52 mm from the prosthetic interface. We first established a calibrated flow-velocity profile corresponding to the study of the support inside the circuit without any prosthesis. We measured the velocity profiles for each prosthesis corresponding to four crimp densities obtained by stretching the grafts. RESULTS: the crimping of PET textile prostheses led to a decrease of flow velocity especially closer to the prosthetic surface. The decrease of flow velocity was dependent on the model of prosthesis. This decrease of flow velocity is described by the following negative exponential law: DeltaV=a times b(-x)where (a) is the crimp density and (b) the fluid viscosity. CONCLUSIONS: flow velocity near a prosthetic surface is influenced by the morphology of the crimping. The impact of crimping on the flow velocity in a vascular prosthesis can be predicted by computer simulation models. This may provide the optimal shape of crimping for each prosthesis.

Blood Flow Velocity↗
PubMed2001

Liver and kidney foreign bodies granulomatosis in a patient with malocclusion, bruxism, and worn dental prostheses.

Granulomatous reactions caused by foreign bodies have been described in drug abusers, in subjects exposed to occupational pollutants, and more rarely, in association with the use of prosthetic devices. We describe a 62-year-old patient with multiorgan parenchymal granulomatosis caused by inorganic debris of unknown origin. The patient presented with fever, hepatosplenomegaly, progressive cholestasis, and acute renal failure. Liver and kidney biopsies showed the presence of noncaseating epithelioid giant-cell granulomas containing scattered polarizable particles. Similar particles were also present in stools. Studies by innovative scanning electron microscopy and energy-dispersive microanalytical techniques showed that the particles isolated in liver, kidney, and stools were made by feldspars, the main component of porcelain. No occupational or environmental exposure to these materials could be identified in this patient and the only reliable source of the porcelain debris turned out to be constituted by 2 dental bridges evidently worn because of a possible inappropriate construction, malocclusion, and bruxism. The porcelain of the dental prostheses had the same elemental spectrum of the particles isolated from stool specimens and liver-kidney granuloma. After identification of the dental prostheses as the most likely source of ceramic debris, and after their removal, the particles from stool specimens disappeared. The patient was then treated with steroids leading to a remission of the clinical symptoms and a decrease in granulomatous inflammatory reaction in both liver and kidney. This is the first report suggesting that a foreign body systemic granulomatosis can be associated with worn dental prostheses.

Bruxism↗
PubMed2001

Cementless total hip arthroplasty in young Chinese patients: a comparison of 2 different prostheses.

Sixty-one primary cementless total hip arthroplasties were performed in 45 Chinese patients <40 years old. There were 27 Anatomic Medullary Locking (AML, Depuy, Warsaw, IN) prostheses and 34 Porous Coated Anatomic (PCA, Howmedica, Rutherford, NJ) prostheses. The average follow-up was 7.6 years (range, 3-11 years). Ten hips (16%) were reoperated; the reason was polyethylene wear with or without osteolysis in 7 hips. Osteolytic lesion was present in 34 hips (56%). The cumulative successful rate at 10 years was 67% using reoperation for any reason as the endpoint. The cumulative successful rate was 98%, however, if revision for aseptic loosening was used as the endpoint. The 2 prostheses did not show significant differences in most parameters except that the PCA hips had significantly more acetabular loosening (P =.02) and periprosthetic osteolysis (P =.01).

Adult↗
PubMed2001

Vital staining of bone in stable, retrieved femoral surface replacement prostheses: a microscopic study of undecalcified ground sections.

We used vital staining with tetracycline to detect viability of bone at the bone-cement interface in 11 stable ICLH femoral surface replacement prostheses that were retrieved at revision surgery for acetabular loosening. The resected femoral heads were processed for undecalcified ground sections with the prostheses in situ. All sections showed direct bone-to-cement contacts. Bone in direct contact with or close to the cement sometimes showed an abnormal staining, indicating that the bone was not fully mineralized. Areas with fluorescence were observed within all femoral heads but never in direct bone-to-cement contact. From this study, we conclude that the mechanical stability of these cemented femoral surface replacement prostheses depends mainly on the original bone present at the time of primary operation.

Acetabulum↗
PubMed2002

Histologic and quantitative wear particle analyses of tissue around cementless ceramic total knee prostheses.

We histologically analyzed tissue biopsy specimens obtained from 4 cases of revised cementless ceramic knee prostheses. Particles were isolated from the specimens, and their size and composition were determined. Implants were removed for aseptic loosening at an average of 64 months. Histologically, polyethylene particles were seen in all cases. The concentration of the particles showed wide variation among cases. The concentration of the particles also showed a wide variation among different biopsy locations, suggesting that the particles were not distributed uniformly around the knee prostheses. Although we analyzed only 4 cases, our results show good correlation between radiographic evidence of geographic osteolysis and the concentration of wear particles. Multiple biopsy specimens may be necessary to characterize adequately particle migration around knee prostheses.

Aged↗
PubMed1978

[Replacement of the thoracic aorta by sealed dacron prostheses (author's transl)].

Dacron prostheses for replacement of the thoracic aorta were sealed with bioadhesive following the Viennese method. Native human fibrinogen was brought to coagulation by adding thrombin. Factor XIII was also added in order to accelerate polymerisation and to reinforce fibrin formation in the presence of thrombin and CaCl2, thus producing a stable thrombus. In order to avoid local fibrinolysis a fast but short-acting as well as a slow but longer-acting antifibrinolytic agent was added. This method was applied in twenty patients. The prostheses remained completely impermeable to blood after resuming circulation in spite of full heparinization. No post-operative haemorrhages from the prostheses were observed.

Aorta, Thoracic↗
PubMedDate not supplied

[Long-term results of the Blauth knee prosthesis--current status of hinged knee prostheses].

AIM: Currently there is widespread use of unconstrained knee arthroplasty even in severe deformities of the knee. In order to ascertain the value and future of constrained knee prostheses, we have assessed the results of the Blauth knee prosthesis and compared them with the results of unconstrained knee prostheses. METHODS: In a retrospective analysis we examined 227 Blauth knee prosthesis implantations performed between 1985 and 1997. Using endpoints of prosthesis removal, infection and aseptic loosening, the 10-year survivorship analysis was evaluated. RESULTS: The analysis shows a 10-year survivorship of 90.1 % using aseptic loosening or infection as an endpoint and 96.2 % using removal as an endpoint. CONCLUSION: The first designs of constrained knee prostheses were associated with a high failure rate, while more recent designs like the St. Georg knee prosthesis and the Blauth knee prosthesis show long-term results similar to condylar designs. Since there has been a large increase of knee endoprosthesis implantations in the last years, a constrained knee prosthesis with excellent long-term results remains a valuable implant in cases of revisions and difficult knee arthroplasty.

Arthroplasty, Replacement, Knee↗
PubMed2006

Rehabilitation of orbital cavity after total orbital exenteration using oculofacial prostheses anchored by osseointegrated dental implants posed as a one-step surgical procedure.

BACKGROUND: Total orbital exenteration is a radical surgical procedure, which typically involves the removal of the entire contents of the orbit including the periorbita, leaving the patient with a deep orbital deformity and results in devastating cosmetic, functional, and psychological consequences requiring difficult and challenging procedures for oculoplastic surgeons. Oculofacial prostheses retained by endosseous dental implants present an attractive and viable alternative when aesthetic and functional demands are beyond the capacity of local reconstructive efforts. PATIENTS AND METHODS: A 72-year-old woman presenting a malignant melanoma of the right eyelids and a 77-year-old man presenting a sebaceous carcinoma of the left upper eyelid underwent a total exenteration followed by positioning of endosseous implants (Straumann system Dental implants) as an integrated one-step combined surgical procedure. The oculofacial prosthesis was placed after epithelialization of the orbital cavity. RESULTS: The implants were perfectly osseointegrated without any complications, providing sufficient retention of the prostheses. A satisfactory aesthetic outcome has been achieved for both patients. CONCLUSIONS: Oculofacial prostheses anchored by osseointegrated dental implants placed as one-step surgical procedure ensure an adequate aesthetic result as well as a considerably decreased rehabilitation time and present a satisfactory solution when reconstruction is not a suitable option.

Dental Implants↗
PubMed1983

Two years experience with Medtronic-Hall prostheses in 75 patients with special reference to its thrombogenicity and hemolysis.

Seventy-five patients received 80 Medtronic-Hall valve prostheses during a 24-month period at the Beilinson Medical Center. The mean age was 50 years and the majority of patients had rheumatic heart disease. All operations were elective. There were 4 early and 2 late deaths (8%). Four patients needed re-operation for paravalvular leaks, 3 of them survived the second operation and one patient with prosthetic valve endocarditis did not. One patient was re-operated on successfully because of a mycotic aneurysm in the ascending aorta. Mild subclinical hemolysis (elevated SLDH and reduced haptoglobin) was found in the majority of patients. Hemolysis was found to be significantly lower in type D 16 prostheses patients. Mild hemorrhagic complications occurred in 2 patients due to anticoagulant therapy. Three patients suffered from prosthetic valve endocarditis (PVE), 2 of them responded to prompt medical therapy. There were no thromboembolic episodes. Most surviving patients experienced marked postoperative improvement. Within the 24-month follow-up period, the Medtronic-Hall valve compared favorably with other disk or ball prostheses previously and currently used in our department.

Adolescent↗
PubMed1988

Implantation of 20 cm long polyurethane vascular prostheses in the femoral artery of dogs. Preliminary results.

In a preliminary experiment externally reinforced polyurethane prostheses measuring 20 cm in length, with an inner diameter of 3 mm, were implanted in a loop in the femoral artery of six dogs. The dogs received 250 mg acetylsalicylic acid and 25 mg dipyridamol three times a day as anti-thrombocyte aggregation therapy starting three weeks prior to surgery. Anti-thrombocyte aggregation therapy was continued throughout the study. All prostheses remained patent 8, 9, 15 and 17 months after implantation. Patency was confirmed by palpation and Doppler ultrasound measurements. Preliminary results suggest that in clinically relevant situations, these prostheses could function well over prolonged periods of time.

Animals↗
PubMedDate not supplied

[Is GSB knee prosthesis implantation for patellar problems still justifiable? Experiences and results based on 230 implanted GSB knee joint prostheses].

In our clinical the GSB-prosthesis has proved to be a good therapeutic concept. In 1988 we controlled 230 patients who had got GSB-prostheses in the years 1979-1987. The average age of our patients was 75 years. Most times surgery had been done because of idiopathic osteoarthrosis, rarely because of post-traumatic or rheumatoid arthritis. Indications for surgery were usually severe pain, limited range of movement and deformities of the knee joint. In the beginning of the studied period we had implanted GSB-type I-prostheses, later we had implanted GSB-type II-prostheses with or without femoropatellar surface. We achieved good results in pain reduction and in range of movement. However the major complications were caused by the patella. These patients had problems at climbing stairs, pain at the beginning of movements and at getting up from chairs. They presented with increased pain sensitivity at the tip of the patella and to friction of the patella. Regular radiological findings were severe destructions or fractures of the upper patellar pole. These problems led in 40 cases (17% of our cases) to reoperations until 1988 (At all we reoperated 50 times because some patients needed additional reoperations). According to our studies results there will be a need for reoperations in about 50 other cases. We discuss the following reasons for this high rate of severe patellar complications demanding re-surgery: 1. Localisation of the patella: according to our studies the patella is frequently dranged cranially, seldom laterally. 2. Often we found an internal rotation of the tibia against the femur.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1981

[Diagnosis of loosening of carbon-made cup prostheses by radionuclide imaging (author's transl)].

Diagnosis of loosening of joint prostheses has become easier by using radionuclide imaging in addition to common radiography. Double-cup hip prostheses have been used more and more in joint surgery of younger patients in the last ten years. But early signs of loosening of the metal cup are difficult to demonstrate because of the high absorption rate of the used materials. Cup protheses of carbon have been implanted since several months in the Orthopedic Clinic Giessen. Tests in a model and in a patient have shown, that it might be possible to evaluate loosening of carbon-cup prostheses by radionuclide imaging.

Adult↗
PubMed2000

Effect of adhesive retention on maxillofacial prostheses. Part I: skin dressings and solvent removers.

STATEMENT OF PROBLEM: The success of most maxillofacial prostheses depends on retention by medical adhesives. Products such as Smith-Nephew's Skin-Prep (SP) are available that can be used on the skin that could improve prosthesis adhesion protective dressing. The removal of adhesive from the skin is also problematic, so solvents, such as Uni-Solve adhesive remover (US), are often used. PURPOSE: This study measured the removal force of silicone elastomer strips with 2 adhesives from the skin of human subjects during the day, as affected by the use of SP and US, and determined the site of adhesive failure. MATERIAL AND METHODS: Silicone rubber strips were applied in a predetermined random order to the ventral arm surfaces of 20 human subjects. US was applied to half the sites 1 day before testing. SP was also applied to half the sites just before Epithane-3 (E3) or Secure(2) Medical Adhesive (SMA) were used to adhere the strips. They were peeled from the skin 6 hours later in an Instron at a rate of 10 cm/min. RESULTS: A 3-way within-group MANOVA revealed significant differences without interactions between adhesives (SMA=96.3 N.m, E3=24.1 N.m; P<.0005) and between use or nonuse of SP (SP=65.8 N.m, no SP=54.6 N.m; P<.0005). The use of US was not significant (no US=61.8 N.m, with US=58.6 N.m; P=.197). SMA adhered to the prostheses, whereas E3 adhered to the skin, leaving a residue (Fisher exact test; P<.0003). CONCLUSION: The combination of SMA and SP showed the highest adhesive bond strength. Overall, SMA was 3 to 5 times more retentive than E3. SP improved adhesion of both SMA (15%) and E3 (27%). SMA was still far more retentive. US had no effect on retention. SMA remained on the prostheses, whereas E3 left a difficult-to-remove residue on the skin.

Adhesiveness↗
PubMed2001

In vitro testing of the bond between soft materials used for maxillofacial prostheses and cast titanium.

STATEMENT OF PROBLEM: The choice of soft materials for maxillofacial prostheses is important for covering extraoral defects after tumor surgery or radiation therapy. The use of cast commercially pure titanium as reinforcement seems to be a suitable option. PURPOSE: Making use of the advantages of titanium frameworks for maxillofacial prostheses requires exploring ways of combining it with soft materials. This study investigated such combinations and evaluated discoloration of the soft material to determine whether it was attributable to the titanium reinforcement. MATERIAL AND METHODS: Five soft materials used for maxillofacial prostheses and their bond strengths to cast titanium were tested. Different ways of conditioning the titanium surface and different adhesives were used. Plain mechanical retention was also studied. The Gretag SPM 100 was used to determine the potential effects on coloring after 24 hours of radiation in the Suntest rapid exposure unit. RESULTS: Suitable material combinations for bonding soft materials to titanium were found for all soft materials studied. Bond strength varied depending on the chemical basis of the soft material. Results indicated that maximal bond strengths were obtained by the combinations Supersoft with Super-Bond, Supersoft with subsequent silicoating, and bonding with Dentacolor connector. Few color shifts attributable to the titanium reinforcement were evident in the 2-mm layers of the soft materials applied. CONCLUSION: The results of this study showed that it is possible to combine a titanium framework and soft silicone materials.

Acrylic Resins↗
PubMed1998

Prolonged suppressive antibiotic therapy for infected orthopedic prostheses.

Prolonged suppressive antibiotic therapy may be an alternative to removal of infected orthopedic prostheses in some patients. However, the efficacy of prolonged suppressive antibiotics is not well established. We retrospectively reviewed 18 patients with infected orthopedic prostheses who had been treated with prolonged antimicrobial suppression during the last 10 years. Eighteen episodes of infection were identified in these 18 patients. There were nine men and nine women, and the mean age was 66 years (range, 31-83 years). All patients had a functional prosthesis and were treated with surgical debridement, retention of the prosthesis, and administration of intravenous antibiotics for 6-8 weeks, followed by prolonged oral antibiotic suppression. Fifteen of the 18 patients appear to have had a good response and have been able to retain a functional prosthesis. Complications related to antibiotic suppression occurred in 22% but did not necessitate discontinuation of the antibiotic therapy. Prolonged antibiotic suppression is a reasonable alternative to surgery in selected patients with infected orthopedic prostheses.

Adult↗
PubMed1990

Renal siderosis in patients with heart-valve prostheses: clinical implications.

We have studied the clinical and morphological implications of renal siderosis, reviewing the autopsy protocols of 33 patients with valve prostheses in the heart. Seventeen patients had variable amounts of iron in the proximal tubules of the kidney. Renal siderosis was more frequent in women, in patients with longest time of evolution from the surgical procedure, and in patients with two valve prostheses. Histologically three degrees of renal siderosis may be defined: mild and moderate degrees of iron overload do not alter the kidney architecture, but kidneys, with severe siderosis show tubular atrophy and interstitial fibrosis. Episodes of acute renal failure (ARF) were more frequent in patients with more pronounced iron deposits, especially in the premortem stages. We conclude that renal siderosis may damage the proximal tubular epithelium of patients with valve prostheses in the heart; patients with renal overload of iron are more susceptible to episodes of ARF.

Acute Kidney Injury↗