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At least 127 records · Page 7Linked to original sources
PubMed1993

Patency and morphology of fibrous polyurethane vascular prostheses implanted in the femoral artery of dogs after seeding with subcultivated endothelial cells.

A cell culture line was established from enzymatically-derived canine jugular endothelial cells and further cultured. Whenever sufficient cells were present, fibrous polyurethane vascular prostheses, impregnated with gelatin and coated with fibronectin, were seeded with 4.8 x 10(5)/cm2 cells, sufficient to establish a confluent monolayer, and implanted in the femoral arteries of 16 dogs. A non-seeded prosthesis on the contralateral side served as control. Eight dogs received antiplatelet aggregation medication: 250 mg aspirin together with 25 mg dipyridamole, orally three times daily, starting 2 weeks prior to the implantation operation and continued for the duration of the experiment. Results show that in the non-medicated dogs all control prostheses become occluded within 3 weeks after implantation, whereas five out of eight seeded prostheses remained patent. In the medicated group, two out of eight control prostheses occluded and all seeded prostheses remained patent. Scanning and light microscopy revealed that seeded prostheses were completely lined with endothelial cells (Factor VIII positive stain) week 3 (n = 3) and 12 (n = 3) after implantation, while endothelialisation in control prostheses had advanced only 5 mm into the prostheses in 12 weeks. Two dogs of each group were included in long-term patency studies. We conclude that prostheses seeded with a confluent monolayer of endothelial cells result in superior patency rates for both medicated and non-medicated dogs. No immunological reaction against the (allogeneic) seeded endothelial cells were noted.

Anastomosis, Surgical↗
PubMed2001

[Total trapezometacarpal prostheses: concepts and classification study].

This paper is an attempt to classify the different types of trapezio-metacarpal total prostheses according to their bio-mechanical principle and to compare the bio-mechanics of these prostheses to that of the normal trapeziometacarpal joint. The trapeziometacarpal joint has two approximate centres of rotation (one in the proximal metacarpal, one in the trapezium), two degrees of freedom and two arc of mobility about 70 degrees. The mechanical model of the trapeziometacarpal joint is a universal-joint called "cardan" with three constraint forces (one axial compression force, and two shear forces, radial and posterior) and one constraint moment around the longitudinal axis. The trapeziometacarpal prostheses may be classified in two main categories: the most frequently used are the "ball and socket" prostheses. Several prostheses, including the surface replacement prostheses have the mechanical characteristics of an universal joint (cardan). Ball and socket prostheses have one centre of rotation, 3 degrees of freedom, three constraint forces in three directions and no constraint moment when "cardan" or surface prostheses have two centres of rotation and 2 degrees of freedom; three constraint forces and one constraint moment. Trapeziometacarpal prostheses may also be classified according to their arc of mobility, or according to their mode of primary fixation (cemented, non-cemented), "press-fit", expansion and to their secondary fixation (hydroxyapatite).

Biomechanical Phenomena↗
PubMedDate not supplied

A survey of the satisfaction of upper limb amputees with their prostheses, their lifestyles, and their abilities.

Seventy Australian upper limb amputees responded to a detailed postal questionnaire asking how often they wore their prostheses and their level of satisfaction with both their prostheses and their functional abilities. Fifty-six percent of amputees wore their limbs "once in a while" or "never." Prostheses were most often worn "all the time" for work and social activities. The amount of time amputees wore their prostheses was moderately associated with their level of satisfaction with their prostheses. The association between the amount of time amputees wore their prostheses and their level of satisfaction with their functional abilities was very low. Their prostheses were rated as "fair" or "not acceptable" by 64% of amputees. Sweating was rated as "not acceptable" by 55%. This may well be a significant contributing factor to the low prosthetic use. The amputees who did not wear prostheses did not have any greater satisfaction with their ability to do the tasks they want to do than the amputees who wore prostheses.

Adult↗
PubMed1998

[Voice prostheses with sound-producing metal reed element--an experimental study and initial clinical results].

BACKGROUND: Following total laryngectomy the voice is produced by esophageal speech as well as with voice prostheses by vibrations of pharyngeal mucosal folds. This pharyngeal sound normally has a significantly lower fundamental frequency than the healthy voice (men about 120 Hz, women about 240 Hz, pharyngeal voice about 70 Hz), which is a handicap especially for female laryngectomy patients. In order to improve the postlaryngectomy voice, a new type of voice prostheses containing an integrated sound-producing metallic reed element was developed (ADEVA Company, Lübeck, Germany). METHODS/PATIENTS: Thirty-five of these new sound-producing voice prostheses were tested in vitro for different prosthesis-specific physical parameters (pressure, flow, sound pressure, flow resistance, frequency range). In 15 voice prosthesis speakers, a sound-producing prosthesis was introduced during a routine outpatient visit. Besides measurement of the above mentioned physical parameters in patients with conventional and sound-producing prostheses, the resulting voice as also evaluated by means of a video recording. RESULTS: In vitro all prostheses with the metallic reed element produced a clear sound. Flow resistance of the prostheses was slightly elevated by the reed element. Insertion of the prostheses was hindered by the reed element. Period of uninterrupted sound production was prolonged after insertion of a sound-producing prosthesis and patients could speak on a lower pressure level, but the sound of the reed element was permanently distinguishable only in 6 of 15 patients. CONCLUSIONS: In principle a variation of the pharyngeal voice by means of a sound producing element, which is integrated into a voice prosthesis, is possible. The current design of the metallic reed element tested is not yet suitable for routine clinical use: 1. The reed element is too sensitive and is easily damaged during insertion, so the insertion device has to be improved. 2. The sound producing element is blocked by small amounts of tracheal secretions, so that this element should be replaceable separately without requiring removal of the silicone value (if possible by the patient himself). Prior to insertion of the sound producing voice prosthesis the maximum air flow through the shunt should be measured to determine if the patient can produce the necessary air flow for activation of the reed element. A further improvement for these special types of voice prostheses would be a sound producing element, which generates a variable frequency of sound. Limiting the patient to only one fundamental frequency creates a monotone, which does not sound naturally. Initial progress toward a sound-producing voice prostheses has been made. This should be followed by the necessary improvements in order to improve the feasibility of this design for routine clinical use.

Equipment Failure Analysis↗
PubMed2000

Comparison of first- and second-generation prostheses for endoluminal repair of abdominal aortic aneurysms: a 6-year study with life table analysis.

PURPOSE: The outcome of endoluminal repair of abdominal aortic aneurysms with two generations of prostheses was analyzed and compared. METHODS: Between May 1992 and December 1998, 266 patients underwent elective endoluminal repair of an AAA. First-generation prostheses were used in 118 patients (group I), and second-generation prostheses were used in 148 patients (group II). The two groups were similar in age, sex, and size of AAA. The proportion of patients with comorbidities was higher in group I than in group II, but not significantly. First-generation devices were characterized by large (24F internal diameter) delivery systems, one-piece construction, and a lack of metallic support throughout their length. Second-generation devices had smaller (21F or smaller internal diameter) delivery systems, modular construction, and a metallic frame throughout the length of the prostheses. The major end-point criteria were survival and successful endoluminal repair. Success was defined as the exclusion of the aneurysm sac from the circulation, with stability or the reduction in AAA maximum transverse diameter. Persistent endoleaks were classified as failures, irrespective of whether they were subsequently corrected by means of secondary endovascular intervention. The minimum follow-up period was 5 months for each of the 266 patients. Analysis was performed by means of the life-table method. RESULTS: Perioperative mortality was not significantly different between group I (4.2%) and group II (2.7%). There was a statistically significant difference between the survival curves of the two generations, which favored group II (P =.012). There was a significant (P <.001) difference between the two generations of patients in their conditional probability of graft failure when the competing risk of all-cause mortality was considered. Second-generation patients were at a lower risk of graft failure than first-generation patients. The probability of failure, expressed as a proportion of grafts failing at 2 years, was 0.15 for patients with second-generation prostheses and 0.33 for patients with first-generation prostheses. CONCLUSION: Endoluminal AAA repair is a safe procedure, whether first- or second-generation prostheses are used. Survival and probability of graft success were significantly higher with second-generation prostheses than with first-generation prostheses. This improvement in outcome resulted from a combination of increasing clinical experience and advances in technology. A more accurate evaluation of the role of the endoluminal method in AAA repair would be achieved by studying patients in whom second-generation devices were used, rather than longer term studies in which first- and second-generation devices were used.

Aged↗
PubMed2002

The use of [18 F]fluorodeoxyglucose positron emission tomography to differentiate between synovitis, loosening and infection of hip and knee prostheses.

Pain is a common unspecific symptom in orthopaedic prosthetics. The accurate differentiation between synovitis, loosening or infection is often difficult with conventional X-rays, arthrography or bone scintigraphy. Because of the high glucose uptake of inflammatory cells, [18F]fluorodeoxyglucose (18F-FDG) is an appropriate tracer for the evaluation of suspected inflammation or infection. In this preliminary study we describe 18F-FDG PET findings in patients referred for evaluation of painful hip or knee prostheses. We studied 23 patients with 28 prostheses, 14 hip and 14 knee prostheses, who had a complete operative or clinical follow-up. 18F-FDG PET scans were obtained with an ECAT EXACT HR+ PET scanner. High glucose uptake in the bone prostheses interface was considered as positive for infection, an intermediate uptake as suspect for loosening, and uptake only in the synovia was considered as synovitis. The imaging results were compared with operative findings or clinical outcome. PET correctly identified three hip and one knee prostheses as infected, two hip and two knee prostheses as loosening, four hip and nine knee prostheses as synovitis, and two hip and one knee prostheses as unsuspected for loosening or infection. In three patients covered with an expander after explantation of an infected prosthesis PET revealed no further evidence of infection in concordance with the clinical follow-up. PET was false negative for loosening in one case. Our preliminary results suggest that FDG PET could be a useful tool for differentiating between infected and loose orthopaedic prostheses as well as for detecting only inflammatory tissue such as synovitis.

Adult↗
PubMed1989

Improved healing of microvascular PTFE prostheses by induction of a clot layer: an experimental study in rats.

This study was undertaken to test the hypothesis that the induction of a clot layer on the graft surface of microvascular polytetrafluoroethylene (PTFE) prostheses might improve their healing. PTFE microvascular prostheses (n = 18), mechanically roughened PTFE microvascular prostheses (n = 18), and Chitosan-impregnated PTFE microvascular prostheses (n = 18) (all prostheses: length 1 cm, inside diameter 1.5 mm, fibril length 30 microns) were implanted into the abdominal aortas of rats and were evaluated at 3 days (n = 3), 10 days (n = 3), 3 weeks (n = 6), and 6 weeks (n = 6) with regard to the presence or absence of a clot layer and with regard to the amount of graft healing. All untreated PTFE prostheses were never found to be covered with a clot layer, only scarcely with some platelets, and showed poor neoendothelial healing; even at 6 weeks after implantation, there was only endothelial cell coverage near the anastomotic sides (coverage = 19 +/- 4 percent). The endothelial cells were present directly on the graft surface. In contrast, both the roughened and the Chitosan-impregnated PTFE prostheses were completely covered with a thin clot layer upon implantation and demonstrated significantly better neoendothelial healing (endothelial cell coverage at 6 weeks = 76 +/- 22 percent and 75 +/- 18 percent, respectively; p less than 0.001); moreover, in these prostheses, the endothelial cells were present on a matrix of smooth-muscle cells, which covered the graft surface completely. These results confirm our hypothesis that the induction of a clot layer on the graft surface of microvascular PTFE prostheses improves their healing.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2003

Migration of metal-on-metal versus ceramic-on-polyethylene hip prostheses.

In a prospective randomized study, 32 metal-on-metal prostheses and 29 ceramic-on-polyethylene prostheses of similar design were implanted in 59 patients. Radiolucency, cup migration, wear, and function were examined after a minimum of 2 years followup (followup rate, 87%). The purpose of the current study was to evaluate whether higher frictional torque of metal-on-metal will lead to a higher rate of early metal-on-metal cup loosening. A computer-assisted method was used for wear and migration measurements of the acetabular component. Metal-on-metal prostheses migrated in a craniocaudad direction significantly less than ceramic-on-polyethylene prostheses. The mean total migration for both types of prostheses exceeded 1.5 mm at 2 years. Clinically, no difference between the two prostheses regarding activity, pain, or range of motion was found at 2 years. As migration of metal-on-metal prostheses was not higher in comparison with ceramic-on-polyethylene prostheses, the expected higher frictional torque of metal-on-metal prostheses did not increase migration during short-term followup. The different debris produced by both bearings did not influence the short-term results of this study, but might cause different long-term results.

Aged↗
PubMed1994

Within-subject comparisons of implant-supported mandibular prostheses: psychometric evaluation.

In a within-subject cross-over clinical trial, psychometric and functional measurements were taken while 15 completely edentulous subjects wore mandibular fixed prostheses and long-bar removable implant-supported prostheses. In this paper, the results of a psychometric assessment are presented. Eight subjects first received the fixed bridge and seven the removable type. After having worn a prosthesis for a minimum of two months, subjects responded to psychometric scales that measured their perceptions of various factors associated with prostheses. They also chewed test foods while masticatory activity was recorded. The prostheses were then changed and the procedures repeated. At the end of the study, patients were asked to choose the prosthesis that they wished to keep. Patients assigned significantly higher scores, on visual analogue scales, to both types of implant-supported prostheses than to their original conventional prostheses for all factors tested, including general satisfaction. However, no statistically significant differences between the two implant-supported prostheses were detected except for the difficulty of chewing carrot, apple, and sausage. For these foods, the fixed prostheses were rated higher. Subjects' responses to category scales were consistent with their responses to the visual analogue scales. These results suggest that, although patients find the fixed bridge to be significantly better for chewing harder foods, there is no difference in their general satisfaction with the two types of prostheses.

Adaptation, Psychological↗
PubMed1992

Improved healing of small-caliber polytetrafluoroethylene vascular prostheses by increased hydrophilicity and by enlarged fibril length. An experimental study in rats.

This study was undertaken to test whether increasing the hydrophilicity of small-caliber polytetrafluoroethylene vascular prostheses by alcohol pretreatment or increasing their fibril length might improve their healing without affecting their patency. Polytetrafluoroethylene vascular prostheses (length 1 cm, inside diameter 1.2 mm) (1) with a fibril length of 30 microns (control group; n = 18), (2) pretreated with alcohol (n = 18), or (3) with a fibril length of 60 microns (n = 18) were implanted into the abdominal aorta of rats. The prostheses were evaluated by means of routine light and scanning electron microscopy during a 6-week period after implantation. All prostheses were patent at harvesting. On implantation, the control polytetrafluoroethylene vascular prostheses were only scarcely covered with platelets. At 6 weeks they had healed in a small area adjacent to the anastomoses only. In contrast, both the alcohol-pretreated polytetrafluoroethylene prostheses and the polytetrafluoroethylene prostheses with a fibril length of 60 microns were completely covered by a thin clot layer on implantation. At 6 weeks after implantation these prostheses had almost completely healed as a result of organization of the thin clot layer by ingrowth of both endothelial and smooth muscle cells. These results demonstrate that increasing hydrophilicity of polytetrafluoroethylene vascular prostheses by alcohol pretreatment or enlarging their fibril length improves their healing by induction of a thin luminal clot layer. This clot layer provides a suitable matrix for ingrowth of both endothelial and smooth muscle cells and does not lead to thromboembolic complications.

Animals↗
PubMedDate not supplied

Improved healing of small-caliber polytetrafluoroethylene prostheses by induction of a clot layer: a review of experimental studies in rats.

This report reviews our experiments that have been undertaken to test the hypothesis whether the induction of a clot layer on the graft surface of small-caliber polytetrafluoroethylene (PTFE) prostheses might improve their healing. PTFE prostheses with a fibril length of 30 microns, PTFE prostheses with a fibril length of 30 microns and either impregnated with Chitosan, or pretreated with alcohol or mechanically roughened, and PTFE prostheses with a fibril length of 60 microns (all prostheses: length 1 cm, ID 1.5 mm) were implanted into the abdominal aorta of rats and were evaluated from 1 day up till 6 weeks after implantation with regard to the presence or absence of a clot layer and with regard to the amount of graft healing. All untreated PTFE prostheses were never found to be covered with a clot layer and showed poor neoendothelial healing: even at 6 weeks after implantation, there were only endothelial cells near the anastomotic sides, directly on the graft surface. In contrast, all other PTFE prostheses were completely covered with a clot layer upon implantation and demonstrated almost complete neoendothelial healing after 6 weeks. Moreover, in these prostheses, the endothelial cells were present on a matrix of smooth muscle cells. These results confirm our hypothesis that the induction of a clot layer on the graft surface of PTFE prostheses improves their healing: the clot probably functions as a provisional matrix for the regeneration of arterial wall tissue, just as occurs in normal arterial wall repair.

Animals↗
PubMed1988

[Doppler echocardiography in assessing mechanical and biological heart valve prostheses].

The study was performed to assess Doppler echocardiographic features of mitral and aortic prosthetic valves of different types with both normal and abnormal function. Two hundred and twenty-three patients with 250 prostheses were studied. Two hundred eight valves (111 mitral, 95 aortic and 2 tricuspid) were considered to be functioning normally after clinical examination, phonocardiography and M-mode and 2D echocardiography. This group enabled us to define normal Doppler echocardiographic findings for different types of prosthesis. In mitral position, peak (p) and mean (m) gradients were lower for disc prostheses and higher for ball and biological prosthetic valves; values of effective orifice area (A), calculated by pressure half-time method, were lower for biological and ball prostheses and higher in disc valves. Results were as follows: St. Jude (p 10.6 mmHg, m 3.9 mmHg, A 2.7 cm2), Duromedics (p 10.6, m 4.3, A 2.8), Björk-Shiley (p 10.4, m 4, A 2.3), Omniscience (p 14.2, m 6.2, A 2.1), Starr-Edwards (p 15.9, m 5.4, A 2.1), Hancock (p 14.7, m 6, A 2), Carpentier (p 13.2, m 5.4, A 1.9). Mild regurgitation, considered "physiological", was found in 2/8 Carpentier valves and in 3/34 St. Jude prostheses. In aortic valves lower peak gradients were found in Lillehei (18.3 mmHg), St. Jude (23.8 mmHg), Björk-Shiley (26 mmHg), Duromedics (27 mmHg) and higher values in Starr-Edwards (30.2 mmHg), Hancock (30 mmHg) and Omniscience (35.5 mmHg) prostheses. Mild regurgitation, considered "physiological", was found in 17% of Omniscience valves, 21% of Hancock, 33% of Duromedics, 45% of St. Jude, 60% of Björk-Shiley prostheses. Hancock mitral valves implanted for over 7 years had a mean gradient higher than valves with a shorter period of implantation (7.6 vs 4.85 mmHg, p less than 0.1), whereas the effective orifice area was similar. Hancock aortic valves implanted for over 7 years had a peak gradient slightly higher than the other group (implantation less than 7 years previously), but the difference was not statistically significant. Forty-two valves (19 aortic and 23 mitral) were considered to be malfunctioning. Regurgitation Doppler signals of malfunctioning valves appeared different from those of "physiological" reverse flow; in the former cases forward gradient was higher than normal prostheses. In stenotic aortic prostheses, peak systolic gradient was greatly increased; in stenotic mitral prostheses, a very significant increase in mean gradient and a great decrease in effective orifice area were found. In 14 patients who underwent surgical re-operation and in the patient who died before operation, Doppler echocardiographic findings were confirmed.(ABSTRACT TRUNCATED AT 400 WORDS)

Aortic Valve↗
PubMed2000

Factors influencing use of digital prostheses in workers' compensation recipients.

The purposes of this study were to retrospectively identify factors associated with decreased use of digital prostheses in workers' compensation recipients 6 months after fitting and to identify characteristics of those individuals who requested and received a second set of prostheses after demonstrating consistent use of the first set. One hundred seventy-eight patients fitted with 281 digital prostheses completed a questionnaire 6 months after fitting. Forty-nine patients (28%) stated they never or occasionally used their prosthesis (low utilization) and 42 (24%) stated they used them more than 4 hours per day (high utilization). One hundred ten patients (62%) reported stump problems; 37 (21%) stated that the problem interfered with the use of the prosthesis. High utilization was associated with nonmanual employment after the injury. Low utilization was associated with male gender, stump problems, and a distal amputation level. Ring finger prostheses were least likely to be used; small finger prostheses, most likely. The country of origin of the patient was not associated with frequency of use. One hundred sixty-one patients had received the prostheses at least 3 years before the end of the study; 45% of these patients had requested and received a second set of prostheses. Women were more likely to request and receive a second set than men. We could not accurately predict future use of digital prostheses. Each case must be evaluated on an individual basis. (J Hand Surg 2000; 25A:80-85.

Adolescent↗
PubMedDate not supplied

[Synthetic prostheses used in surgery to repair abdominal wall defects (excluding groin hernias). Characteristics, in situ behaviour and applications].

This study is an updating on synthetic prostheses used today to repair incisional hernias, eviscerations and abdominal wall defects due to a severe infection or a parietal excision of malignant tumours. The present prostheses are the fruits of the constantly developing plastic industry. Their characteristics and types (mesh or patch), together with the materials they are made of, are studied taking this development into account. The tissular reactions caused by prostheses are different depending on whether the material they are made of is an absorbable one or not. Published data on animal experimentation are largely used in this part of the study. A significant part is also allocated to the pathobiology of prostheses infection on which is based prevention of risk infection in the surgical practice. A synthetic prostheses has to be chosen depending on its characteristics and the tissular reactions it generates. In a septic environment, only absorbable prostheses can be used without risk. As for incisional hernias, which allows the authors to refer to their own expérience, the choice also depends on both the surgeon's own conception of the treatment and its purpose. The defect recovery after parietal excision of malignant tumours is eased by the use of a synthetic prostheses. In the future, synthetic prostheses will be even more used than today in the repair of abdominal wall. A present, the materials they are made of keep on being developed.

Abdominal Muscles↗
PubMed1993

Frequency and severity of intravascular hemolysis after left-sided cardiac valve replacement with Medtronic Hall and St. Jude Medical prostheses, and influence of prosthetic type, position, size and number.

Intravascular hemolysis occurs often in patients with mechanical heart valve prostheses, but in most cases is of mild degree and subclinical. The severity of hemolysis is reported to be related to the type, position and size of prostheses used, as well as the presence of valve malfunction. Hemolysis was evaluated in 170 patients with St. Jude Medical (SJM) and 80 patients with Medtronic Hall (MH) prostheses, with normal mechanical function. The presence and severity of hemolysis was assessed on the basis of serum lactic dehydrogenase, serum haptoglobin, blood hemoglobin and reticulocyte levels as well as the presence of schistocytes. Overall, patients with SJM prostheses had greater frequency (51.2 vs 18.7%, p < 0.005) and severity (p < 0.005) of hemolysis than patients with MH prostheses, irrespective of position and size. No patient had decompensated anemia. The frequency of hemolysis was similar in both groups with double-valve replacement, whereas severity was greater with SJM than MH prostheses (p < 0.001). The number and position of the prostheses were correlated with severity of hemolysis: Double-valve replacement and mitral position were correlated with greater hemolysis than single-valve replacement (p < 0.01) and aortic position (p < 0.01). Valve size, cardiac rhythm and time from operation did not correlate either with frequency or severity of hemolysis. It is concluded that in normally functioning SJM and MH prostheses: (1) hemolysis is frequent but never severe; (2) SJM demonstrates greater frequency and severity when compared with MH valve; and (3) number, position, but not size, significantly affect the severity of hemolysis.

Adult↗
PubMed1998

Comparison of conventional and wire mesh expandable prostheses and surgical bypass in patients with malignant esophagorespiratory fistulas.

BACKGROUND: Patients who present with malignant esophagorespiratory fistula continue to provide a significant palliative challenge to gastroenterologists and surgeons. METHODS: This retrospective series reviewed 29 patients treated with conventional prostheses (13 patients), expandable wire mesh-coated prostheses (12 patients), and surgical bypass with esophageal exclusion (4 patients) between 1982 and 1995. RESULTS: Improvement in dysphagia scores were comparable in all three groups. Fistula occlusion was more successful with expandable prostheses (92%) compared conventional prostheses (77%); however, reinterventions were required more commonly with expandable prostheses, which were also significantly more expensive on a unit cost basis. In selected patients in whom prosthesis placement either was inappropriate or failed, surgical bypass and esophageal exclusion was undertaken. These patients demonstrated good palliation with minimal morbidity and no mortality. CONCLUSIONS: Both conventional and expandable prostheses are safe and reasonably straightforward treatment modalities for patients with esophagorespiratory fistulas. Because of ease of insertion and large luminal diameter, expandable metal prostheses will see increasing use in treatment of these difficult patients; however, conventional prostheses will remain a good alternative, especially in patients with extrinsic esophageal compression. When stent placement is either unsuccessful or inadvisable, physiologically fit patients can undergo surgical bypass and esophageal exclusion with good palliation and minimal morbidity and mortality.

Adenocarcinoma↗
PubMed2004

Pore size, tissue ingrowth, and endothelialization of small-diameter microporous polyurethane vascular prostheses.

Small-diameter microporous polyurethane vascular prostheses with an average pore size of between 5 and 30mum at the outer surfaces and 30mum at the luminal surface were prepared. Thirty-two PU and 8 expanded polytetrafluoroethylene (ePTFE) prostheses were implanted into the abdominal aorta of rats for periods ranging from 1 to 8 weeks. Harvested prostheses were analysed histologically and morphologically. The progress of endothelial-like cells and the extent of infiltration of perigraft tissues were quantified. All of the prostheses showed fast growth of endothelial-like cells in the second week, with the PU prostheses having an external pore size of 30mum producing the highest rate. It was also during the second week that perigraft tissue grew most significantly into the prosthetic structure. This coincident may suggest the importance of rapid tissue regeneration for the early endothelial healing. The role of the ingrowth perigraft tissues is likely to support and stabilize the neointima. The thickening of neointima was mainly located at the vicinity of the proximal anastomoses of some of the PU prostheses and was unrelated with the extent of perigraft tissue infiltration. In the PU prostheses, a complete lining of endothelial-like cells was achieved by the end of 4 weeks. Expanded PTFE prostheses displayed smooth, thin intima, very limited tissue ingrowth, and incomplete coverage of endothelial-like cells.

Animals↗
PubMed2001

Freestanding and tooth-implant connected prostheses in the treatment of partially edentulous patients Part II: An up to 15-years radiographic evaluation.

A total of 123 patients were followed between January 1983 and July 1998 with 140 tooth-implant connected prostheses. The age of the patients at prosthesis installation ranged from 20 to 79 years (mean 51.8). 339 (Brånemark(R) system) implants were connected to 313 teeth. The loading time ranged from 1.5 to 15 years (mean: 6.5). 123 patients were randomly selected as a control group with freestanding implant-supported prostheses only. The age of the patients at prosthesis installation ranged from 22 to 78 years (mean 52.3). The loading time for the 329 freestanding (Brånemark(R) system) implants ranged from 1.3 to 14.5 years (mean: 6.2). Evolution of the marginal bone stability around the implant in the tooth-implant connected as well as the freestanding group was studied with respect to the prognosis of the implants. Over the period from 0 to 15 years, there was significantly more marginal bone loss (0.7 mm) in tooth-implant connected versus freestanding prostheses. No significant difference in marginal bone loss was found between the non-rigid tooth-implant connected prostheses versus freestanding prostheses. However, there was a significant difference in marginal bone loss for rigid and multi-connected tooth-implant connected prostheses versus freestanding ones. The results of this study indicate that more bone is lost around implants which are rigidly connected to teeth. This suggests that bending load, which is increased in tooth-implant connected prostheses, might be responsible for this phenomenon. These observations favor the use of freestanding prostheses whenever possible. However, the clinical significance of greater bone loss in rigid versus non-rigid connections might outweigh the annoying phenomenon of tooth intrusion in the case of non-rigid tooth connection, when connection is considered.

Adult↗