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At least 19 recordsLinked to original sources
PubMed1992

[Surgical silicone prostheses in the treatment of biliary tract cancers: long prostheses or short prostheses? Results apropos of 500 cases].

The interest of surgical prostheses in the palliative treatment of biliary tract cancer is well established, on the basis of their good tolerance, the more than 15 year follow up experience and the number of patients operated upon. After exeresis, they allow re-establishment of continuity, either by use of a prosthesis in Y when the right and let ducts can be dissected, or by using two prostheses, a multiperforated long prosthesis reimplanted in the duodenum and a short prosthesis reimplanted in the common bile duct without attaining the sphincter of Oddi. Of the 1000 cases treated, 500 were the object of a statistical analysis, 46 being operated upon by the author, in 60% of cases for biliary tract cancer, either primary or as an extension from the gallbladder. One-third of the patients had advanced lesions and a short survival of less than 3 months. Two-thirds a median survival of 9 months. In 10%, a radical exeresis was performed with survival of more than one year without recurrence of jaundice. Failure of treatment with persistence of jaundice was due to advanced disease for which surgery is unsatisfactory. Essential complications were premature bile leaks (5%) without serious consequences if sufficient drainage was maintained, since it stopped spontaneously, and angiocholitis (6%), the result of territory exclusion or reflux. Recurrence of jaundice was related to extension of the neoplasm to the secondary bile ducts, and to hepatic metastases. Obstruction of the prosthesis before two months was rare (6%) and was preceded by angiocholitis. In the absence of recurrence of the cancer the prosthesis can be replaced surgically without difficulty.

Biliary Fistula↗
PubMed1999

Use of unicompartmental instead of tricompartmental prostheses for unicompartmental arthrosis in the knee is a cost-effective alternative. 15,437 primary tricompartmental prostheses were compared with 10,624 primary medial or lateral unicompartmental prostheses.

Unicompartmental knee arthroplasty (UKA) is known to have a higher risk of revision than tricompartmental arthroplasty (TKA), while UKA implants are generally less expensive than TKA implants. We estimated the costs of implants and hospital stay of both procedures and related the cost difference at primary operation to the difference in number of revisions to be expected. We compared 15,437 primary TKAs and 10,624 primary medial or lateral UKAs. The operations were all done on patients with arthrosis during 1985-1995. By matching patients in the Swedish Patient Administration System with the Swedish National Knee Arthroplasty Register, the groups could be compared regarding the length of the hospital stay. The cumulative revision rate (CRR) and the relative risk of revision were calculated with survival statistics, as well as the risk of a second revision and the risk of infection. The weighted mean cost of the commonest implants in each group was used as an estimate of the implant cost. We found that the TKA patients were, on average, 2 years older at operation and had a lower CRR than the UKA patients-i.e., 10-year CRR of 12% and 16%, respectively. After adjusting for age, gender and year of operation, UKA patients were found to have a 2-day shorter hospital stay and fewer serious complications than TKA patients. The mean estimated cost of a unicompartmental implant was 57% of that of a tricompartmental implant. We conclude, that by using UKA instead of TKA in appropriate patients, money can be saved, even after taking into account the increased number of revisions to be expected.

Age Distribution↗
PubMed1993

Doppler-derived pressure differences in normally functioning aortic valve prostheses. Studies in Björk-Shiley monostrut and Biocor porcine prostheses.

To determine the normal range of maximum and mean Doppler-derived pressure differences for mechanical and bioprosthetic valves in the aortic position, Doppler echocardiography was performed on 239 stable patients with normally functioning Björk-Shiley monostrut (BSM, n = 185) or Biocor porcine (n = 54) prostheses. The interval from aortic valve replacement to echocardiography was 3-9 days. Maximum and mean pressure differences were significantly greater in 21 mm than in 25 or 27 mm BSM prostheses. The pressure differences in 23 mm BSM valves did not diverge significantly from those in 21, 25 or 27 mm valves. The mean pressure difference did not exceed 30 mm Hg in any type or size of studied prosthesis. No significant differences were found in pressure gradients in comparisons between BSM and Biocor prostheses of corresponding sizes. The calculated velocity ratio for BSM prostheses was not significantly influenced by the valve size. We suggest that the normal range of Doppler-derived maximum and mean pressure differences determined in this study be adopted as reference in evaluations of aortic BSM and Biocor valve prostheses.

Aged↗
PubMedDate not supplied

Maintenance requirements of implant-supported fixed prostheses opposed by implant-supported fixed prostheses, natural teeth, or complete dentures: a 5-year retrospective study.

PURPOSE: The purpose of this study was to compare the maintenance requirements of implant-supported fixed prostheses with cantilever arms in edentulous jaws when opposed by fixed prostheses of similar design, by natural teeth, or by complete dentures. MATERIALS AND METHODS: The maintenance requirements for the 5-year follow-up period were obtained by examining the dental records of 37 people. Six were provided with fixed prostheses in both arches, 22 with a fixed prosthesis in the mandible opposed by a complete denture, and 9 with a fixed prosthesis opposed by natural teeth. Everyone was treated with Nobel Biocare implants using standard implant and prosthetic protocols. RESULTS: The denture teeth and acrylic resin were repaired on 44 occasions in the group with implants in both jaws, on 14 occasions in the group with implants opposed by natural teeth, and twice in the group in which the implants were opposed by a complete denture. The group with implants in both jaws was more likely to fracture the gold-alloy framework, which occurred on six occasions. The group with implants in both jaws was significantly different from the other two groups in relation to higher incidence of fracture of the teeth and gold-alloy framework. CONCLUSION: The maintenance requirements of implant-supported fixed prostheses with cantilever arms opposed by fixed prostheses of similar design were much greater than when opposed by natural teeth or complete dentures.

Acrylic Resins↗
PubMed1991

Silicone gel-filled breast prostheses; silicone inflatable breast prostheses: patient risk information--FDA. Notice.

The Food and Drug Administration (FDA) is issuing a notice to promote the dissemination of information on risks associated with silicone gel-filled breast prostheses and silicone inflatable ("saline-filled") breast prostheses to women considering having the devices implanted. This notice addresses an important public health issue presented by the continued marketing and implantation of these unapproved devices. FDA has identified significant deficiencies in premarket approval applications for silicone gel-filled breast prostheses. FDA will regard breast prostheses as misbranded under the Federal Food, Drug, and Cosmetic Act (the act) if their labeling does not provide adequate written information to patients on the risks associated with these devices. Such information should be written so as to be easily comprehensible to most patients and should be provided to patients prior to scheduling implantation, so that patients have sufficient time to review the information and discuss it with their physicians. To satisfy the requirements of the act, such patient risk information must set out the known, suspected, and potential risks associated with implantation of these devices. This notice includes suggested patient risk information sheets as guidance.

Female↗
PubMed1992

[Effect of inadequate filling of deflation of inflatable breast prostheses. Statistical study of 535 inflatable prostheses].

This study was based on a series of 535 inflatable prostheses used for breast reconstruction or augmentation with a mean follow-up of 5.15 years. The authors specifically analysed the statistical correlation between underinflation and deflation due to late rupture. They demonstrated a statistically significant difference between the initial filling of the prostheses which subsequently deflated and the initial filling of all prostheses of the series. The mean filling of prostheses which subsequently deflated was 89% while the mean filling of all prosthesis in the series was 100%. The various pathologies are analysed according to the cosmetic or reconstructive indications. The two series, cosmetic and reconstructive, were homogeneous in terms of filling volume and deflation; the only difference concerned the age distribution. Patients undergoing breast reconstruction with a prosthesis were older than patients undergoing augmentation surgery for small breasts. The authors discuss the advantages and disadvantages of this type of prosthesis.

Adolescent↗
PubMed2004

Energy expenditure and gait characteristics of a bilateral amputee walking with C-leg prostheses compared with stubby and conventional articulating prostheses.

OBJECTIVE: To compare energy cost and stride characteristics during walking with 3 different types of prostheses in a person with bilateral knee disarticulations. DESIGN: Single-case study. Setting Pathokinesiology laboratory. PARTICIPANT: A subject with bilateral knee disarticulations and bilateral transradial amputations secondary to meningococcemia with purpura fulminans. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Energy cost, stride characteristics, and motion analysis. RESULTS: When wearing the C-Leg prostheses, the subject walked the farthest and fastest, with an overall lower rate of oxygen consumption and oxygen cost compared with walking with either of the other prostheses. Gait analysis while the patient was wearing the C-Leg prostheses revealed premature hip extension, absence of knee flexion during loading response, and a rate of swing in the referent range. CONCLUSIONS: Walking in a C-leg was the most efficient method of ambulation for our subject.

Adult↗
PubMed1983

Retrieval analysis of total knee prostheses: a method and its application to 48 total condylar prostheses.

A technique for the classification and quantification of damage in retrieved total knee prostheses is presented and applied to the examination of 48 removed total condylar-type knee replacements. The technique involves inspection of all metallic and polyethylene components for evidence of gross deformation, fracture, and damage to articulating surfaces. A grading system was developed to quantitate surface damage on polyethylene components. Results of the examinations are combined with patient variables (weight, activity level, radiographic findings, time of implantation, and results of histology performed on surrounding tissue) to determine correlations between clinical variables and the mechanical damage experienced by the prostheses. For the 48 total condylar-type prostheses, significant positive correlations were found for the surface damage correlated with the patient's weight and the time the prosthesis was implanted.

Biomechanical Phenomena↗
PubMed1988

Stability of performances of vascular prostheses retrospective study of 22 cases of human implanted prostheses.

Twenty-two cases of vascular graft failures (thrombosis, pseudoaneurysm, dilation, infection) were investigated by means of physicochemical, histological, and ultrastructural studies. A general decrease of mechanical resistance to stress of the prostheses was observed. Its magnitude ranged from 2 to 75% of the values of identical virgin prostheses and there was no relation with the duration of implantation. In addition to the breakage of yarn filaments (SEM), migration of fiber debris (histology) was observed in 7 cases. The structure of the polyester molecule had evolved after implantation. A decrease of crystallinity (x-ray diffraction and differential scanning calorimetry) was noted. These observations raise the question of the established stability of vascular prostheses and emphasize the need for further investigations in human graft retrieval programs.

Biocompatible Materials↗
PubMed2003

Mechanisms of rupture of knitted polyester vascular prostheses: an in vitro analysis of virgin prostheses.

OBJECTIVES: Previous explant retrieval studies have shown ruptures occurring on the remeshing line and the guide line of two types of warp-knitted grafts. The aim of our study was to characterize the mechanisms these ruptures. MATERIALS AND METHODS: We performed an in vitro study of the mechanical and chemical characteristics of virgin prostheses. We studied 2 virgin polyester warp-knitted grafts models: the Cooley Double Velour and the Microvel Double Velour constructed by Meadox (USA), using the following techniques: characterization and de-knitting of the textile structure, circumferential tensile strength, filament dynamometry, critical dissolution time of the filaments and scanning electron microscopy. RESULTS: Both prostheses were constructed in the same way but the texturized yarns of the Cooley graft included twice as many filaments (54) than the Microvel (27). There was more adsorbed tension in the Cooley structure than in the Microvel. The circumferential tensile strength test demonstrated that the Cooley graft always ruptured on the remeshing line and the Microvel graft always ruptured at the interface between the remeshing line and the standard line. Filament dynamometry demonstrated a heterogeneous behavior of the filaments inside the yarns, mainly at the remeshing line of the Cooley graft (27.1 cN/tex +/- 11.5% versus 26.1 cN/tex +/- 2.2% for the guide line and 28 cN/tex +/- 6.7% for the standard knit). Critical dissolution time of the filaments was significantly lower for the Microvel grafts (2.5 sec versus 17.2 sec for the Cooley). CONCLUSIONS: Rupture of knitted polyester prostheses are probably an underestimated phenomenon. They may occur at specific areas of the graft. Further studies are required to determine whether all grafts of this type are at risk.

Blood Vessel Prosthesis↗
PubMed2003

No bias of ignored bilaterality when analysing the revision risk of knee prostheses: analysis of a population based sample of 44,590 patients with 55,298 knee prostheses from the national Swedish Knee Arthroplasty Register.

BACKGROUND: The current practice of the Swedish Knee Register is not to take into consideration if one or both knees in a patient are subject to surgery when evaluating risk of revision after arthroplasty. Risk calculations are typically done by statistical methods, such as Kaplan-Meier analyses and Cox's proportional hazards models, that are based on the assumption that observed events are independent, and this is rarely appreciated. The purpose of this study was to investigate if ignoring bilateral operations when using these methods biases the results. METHODS: The bias of not taking bilateral operations into account was investigated by statistically analysing 55 298 prostheses in 44 590 patients, undergoing knee arthroplasty surgery in Sweden during 1985-1999, using traditional proportional hazards analysis, which assumes that all observations are independent, and a shared gamma frailty model, which allows patients to contribute repeated observations. RESULTS: The effect of neglecting bilateral prostheses is minute, possibly because bilateral prosthesis failure is a rare event. CONCLUSION: We conclude that the revision risk of knee prostheses in general can be analysed without consideration for subject dependency, at least in study populations with a relatively low proportion of subjects having experienced bilateral revisions.

Adolescent↗
PubMedDate not supplied

Are synthetic prostheses really inert? Preliminary results of a study on the biocompatibility of Dacron vascular prostheses and Silicone skin expanders.

This study investigates the histo-pathologic reactions induced by implant of prostheses in Dacron knitted double velour and skin expanders in Silicone elastomers. Particular attention was paid to the effect of these reactions on the tissue itself. In the case of vascular prostheses it was found that fibrous connective tissue tended to accumulate in and around the prosthesis. We also observed widespread lymphohistiocytic infiltration and occasional plasmacytes. Numerous foreign body granulomas were found to be grouped around the filaments of plastic material. The prosthesis itself seemed to be composed of filaments of different calibre, fragmented into particles of varying size. Thus the structure of the prosthesis was modified and discontinued along its whole length. A similar granulomatous inflammatory reaction developed in the case of the skin expander, probably due to the leakage of particles of plastic material through the expander wall, which however did not seem to be affected by the tissue reaction. The findings indicate the need for more detailed research into the material used for prostheses, aimed at determining what modifications the tissues can produce in the synthetic material. Also, it is necessary to follow a multidisciplinary approach which takes into consideration the data available from the chemistry of polymers, fluid mechanics and cell biology.

Adolescent↗
PubMedDate not supplied

[Osseointegrated implants for the retention of restorative jaw prostheses and facial prostheses for functional and esthetic rehabilitation following tumor surgery].

To restore the masticatory function after tumor surgery, 110 transmucosal intraoral implants have been inserted in 21 patients, and 26 percutaneous implants in a total of 9 patients for the stabilization of facial prostheses. While 12 of the intraoral implants had to be removed for lack of bony integration, the losses of the percutaneous implants for the stabilization of facial prostheses were exclusively due to tumor recurrences in the direct vicinity of the implants. Our previous results in the use of osseointegrated implants for the retention of restorative maxillofacial prostheses show a limited incidence of complications and give reason to expect long-term success in functional and esthetic rehabilitation. This method provides a decisive improvement in the quality of the life of tumor patients compared to the procedures used up to now.

Dental Implantation, Endosseous↗
PubMedDate not supplied

Five-year report on partial ossicular replacement prostheses and total ossicular replacement prostheses.

Although much progress has been achieved in the functional restoration of ears damaged by chronic suppurative otitis media since the introduction of tympanoplasty 30 years ago, adequate hearing improvements in ears with loss of the stapedial arch have been the most elusive. It is now recognized that such ears present the surgeon with numerous associated problems that require control for a satisfactory outcome; the problem of establishing an efficient link between the tympanic membrane and oval window has proved the most difficult. The introduction of biocompatible materials was heralded as a possible solution. In order to evaluate the claims for these new materials, the five-year results obtained with one of these, porous polyethylene, were evaluated. The one-year success rate with partial ossicular replacement prostheses was 64%; the five-year success rate was 43%. With total ossicular replacement prostheses the success rate was 59% at one year and 22% at five years. These poor results, coupled with evidence of digestion of porous polyethylene, give little justification for the continued use of this material in tympanoplasty.

Ear Ossicles↗
PubMed1978

[Diagnosis for the localization of cemented intramedullar stem prostheses and ICLH-prostheses of the hip by means of stereo X-ray prints (author's transl)].

It is known that the loosening of artificial hip joints leads to their shift relative to the carrying bone structure. For a quantitative radiological detection of even minimal dislocations fix-points both in the carrying bone structure as well as in the prostheses have to be defined. While for the stem prostheses and cups such points can be defined directly from their geometrical structure, they have to be generated artificially for the carrying bone structure by implanted metal pins, which can easily be detected in the X-ray print. Having defined in this way a complete and appropriate set of fix-points, the position of the prosthesis relative to the bone structure is uniquely defined by the distance vectors between the different fix-points. The main biometrical steps of such a concept as well as their computational formulation and realization are derived; the main advantages and the accuracy of the technique are elucidated and critically discussed.

Biomechanical Phenomena↗
PubMed1998

[Ankle prostheses. Mid-term results after Thompson-Richards and STAR prostheses].

Thirty-seven patients with 20 cemented Thompson-Richards prostheses and 19 cementless S.T.A.R. prostheses (2 bilateral cases) were followed up after 1-12 years. Rheumatoid arthritis was the main diagnosis in both populations, with females dominating. The investigation was based on the Kofoed ankle score. At follow-up the total scoring improved to 86.9 pts. in S.T.A.R. and to 77.7 pts. in T.R.P. replacement. The radiological examination showed a high rate of radiolucency for the tibial component (53.3%) in cemented T.R.P.; subsidence of talar component was seen in 3 cases with T.R.P. In cementless S.T.A.R. prothesis only 3 cases showed small radiolucent lines of the flat tibial component. Talar subsidence was not seen at all. In T.R.P. we had two revisions due to prothesis loosening and one maleollar fracture, giving a cumulative estimated survival rate of 87% at 12 years. In the S.T.A.R. prosthesis group two revisions had to be performed because of one meniscal breakage and correction of meniscal height. The estimated survival rate at 6 years was 94.3%.

Ankle Joint↗