Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PROSTHESES”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 703 records · Page 39Linked to original sources
PubMed1999

Intravascular hemolysis after mitral and aortic valve replacement with different types of mechanical prostheses.

Heart valve replacement with mechanical prosthesis is associated with mild intravascular hemolysis. In this study we evaluated the incidence of hemolysis in patients with different combinations of two mechanical valves. Between 1974 and 1996, 680 patients underwent mitral and aortic valve replacement with mechanical prostheses; we selected 90 patients, divided into six groups according to the prosthetic model (Group A, ball and tilting disc; Group B, ball and bileaflet; Group C, tilting disc and tilting disc; Group D, tilting disc and bileaflet; Group E, bileaflet and tilting disc; Group F, bileaflet and bileaflet; respectively, in mitral and aortic position). Blood tests were performed to check blood hemoglobin, serum lactic dehydrogenase, percent-correlated reticulocyte fraction, serum haptoglobin, and schistocytes. Chi square test was performed for categorical data. ANOVA and Bonferroni tests were performed in order to evaluate significant statistical differences between media and variance of the hematological data. A mild degree of intravascular hemolysis was observed in 30% of patients with double mechanical prostheses. LDH values were above the normal values in all groups, although a significant difference was found only between Group B versus Groups C and D. Reticulocytes and schistocytes and serum haptoglobin values were within the normal range and no differences were found between the groups. Low levels of blood hemoglobin were found in Groups D and F. The difference was statistically significant when compared with Groups A and E. In conclusion, hemolysis is frequent but never severe in patients with mitral and aortic mechanical prostheses. A higher incidence of subclinical hemolysis was found in patients with bileaflet valves regardless of the position of the implant.

Analysis of Variance↗
PubMed1995

Metacarpophalangeal joint prostheses. A review of the clinical results of past and current designs.

The clinical results of past and current hinge, flexible and third generation designs of MP prosthetic joints are reviewed. The hinged prostheses did not achieve acceptable short term clinical results while the silastic and third generation prostheses provided good results with with correction of deformity and adequate range of motion (ROM). These good short term results did, however, get progressively worse with the recurrence of deformities and loss of ROM. It is evident that while most of the existing prostheses can relieve pain and restore appearance, none provide the degree of stability and ROM that is required to restore normal function to the MP joint. The moderate results could be partly due to the stage of the disease at which the surgery is carried out. At present, surgery on patients with rheumatoid arthritis is undertaken at a stage in the disease where the muscles and the ligaments surrounding the joint, and the bone, are generally in a poor condition. Surgery at this stage is really only a salvage procedure.

Arthritis, Rheumatoid↗
PubMed2002

Hip joint contact forces in normal subjects and subjects with total hip prostheses: walking and stair and ramp negotiation.

OBJECTIVE: To calculate the hip joint contact force in normal subjects and subjects with total hip replacements. DESIGN: An observational study of age matched normal subjects and subjects with hip joint replacements. BACKGROUND: Hip joint contact forces have been calculated using musculo-skeletal models and measured in vivo using instrumented hip prostheses. There are few examples of studies performed on subjects in the 40-60 year age range. This study characterises the forces in both normal subjects and subjects with hip joint replacements for these 'young' subjects. METHODS: Motion analysis and force plate data were used as input to a three-dimensional model of the leg. Five male and six female normal subjects and five male subjects with hip prostheses were studied. Each subject was observed walking and negotiating stairs and a ramp. RESULTS: Hip joint contact forces in both thigh and pelvic-based co-ordinate systems are presented. Subjects cadence, speed and stride length are given. CONCLUSIONS: In general subjects with hip replacements exhibited lower hip joint contact forces than age matched normal subjects. It is suggested that this was the results of the lower speeds, stride lengths and cadences adopted by the subjects with hip replacements. RELEVANCE: The characterisation of hip joint contact forces provides essential information for prosthetic joint design and testing. The comparison of hip joint contact forces in normal subjects with those in subjects with prosthetic joints provides evidence of, not only actual use of joints, but also of possible levels of force that might be applied to hip prostheses if subjects returned to normal use.

Adult↗
PubMed2000

A follow-up study of orbital prostheses supported by dental implants.

PURPOSE: This study reports on the use of osseointegrated dental implants for anchorage of orbital prostheses. PATIENTS AND METHODS: Nine patients were treated with 25 implants inserted in the periorbital area after exenteration of the globe. Implants of 9, 11, and 13 mm length, with a diameter of 3.5 mm, were used. RESULTS: All implants were stable at the stage 2 operation and could be connected with abutments. In 7 cases (19 implants), orbital prostheses were fabricated and have been worn for an average of 3 years. One of the 19 implants was lost after 3 years because of load stress. During the mean observation period, there were only slight skin reactions around the transcutaneous abutments. CONCLUSION: These results suggest that normal dental implants can be used to anchor craniofacial prostheses without altering their design or the surgical method.

Adult↗
PubMed1997

Effects of coronally slotted femoral prostheses on cortical bone strain.

The photoelastic method was used to assess the effects on femoral cortical strain of total hip arthroplasty cementless femoral prostheses containing distal coronal slots. Eight cadaveric femurs were tested, although three were eliminated secondary to fractures. Loaded and unloaded cortical strains were determined at 72 points on the implanted femoral cortex and compared with the values obtained in the intact femur. Three different prostheses were sequentially implanted, in a random order, into each femur. The prostheses consisted of a standard solid stem, an identical stem with a coronal slot in its distal one fourth, and an identical stem with a coronal slot in its distal one half. The slotted stems did not enhance axial load transfer to the proximal medial femur but did result in increased proximal medial assembly strains and statistically significant (P < .05) decreased anterior and posterior assembly strains. The increased proximal medial assembly strains are hypothesized to enhance proximal medial femoral loading, while the decreased anterior and posterior assembly strains may minimize operative implantation fractures.

Aged↗
PubMed1999

Microbubbles associated with mitral valve prostheses in pediatric patients.

OBJECTIVES: To assess whether microbubbles are associated with mitral valve prostheses in children and to investigate their relationship to exercise. BACKGROUND: Bright, highly mobile echoes are seen in left heart chambers of patients with mechanical mitral valve prostheses. The clinical importance of those microbubbles is not yet known but they survive long enough to reach the cerebral circulation. No such studies have been reported in children. METHODS: There were 20 male and 10 female patients with a mean age of 10.4 years (range 2-16 years). Transthoracic echocardiography with calculation of cardiac output and ejection fraction was performed at baseline and after exercise following mechanical mitral valve replacement. Studies were evaluated for the presence of microbubbles. The mean time from operation to time of study was 18 months (range 0.2-89 months). RESULTS: Of the 30 children evaluated, 28 (93%) had evidence of microbubbles. Exercise increased the number of microbubbles in 15 of the 26 children. This was positively associated with an increase in cardiac output. CONCLUSIONS: (1) Microbubbles are commonly observed in children with mechanical mitral prostheses and are augmented by exercise. (2) This phenomenon is of a special concern in children due to their expected longevity with the prosthesis.

Adolescent↗
PubMed2003

Radiotherapy dose calculations in the presence of hip prostheses.

The high density and atomic number of hip prostheses for patients undergoing pelvic radiotherapy challenge our ability to accurately calculate dose. A new clinical dose calculation algorithm, Monte Carlo, will allow accurate calculation of the radiation transport both within and beyond hip prostheses. The aim of this research was to investigate, for both phantom and patient geometries, the capability of various dose calculation algorithms to yield accurate treatment plans. Dose distributions in phantom and patient geometries with high atomic number prostheses were calculated using Monte Carlo, superposition, pencil beam, and no-heterogeneity correction algorithms. The phantom dose distributions were analyzed by depth dose and dose profile curves. The patient dose distributions were analyzed by isodose curves, dose-volume histograms (DVHs) and tumor control probability/normal tissue complication probability (TCP/NTCP) calculations. Monte Carlo calculations predicted the dose enhancement and reduction at the proximal and distal prosthesis interfaces respectively, whereas superposition and pencil beam calculations did not. However, further from the prosthesis, the differences between the dose calculation algorithms diminished. Treatment plans calculated with superposition showed similar isodose curves, DVHs, and TCP/NTCP as the Monte Carlo plans, except in the bladder, where Monte Carlo predicted a slightly lower dose. Treatment plans calculated with either the pencil beam method or with no heterogeneity correction differed significantly from the Monte Carlo plans.

Algorithms↗
PubMed1997

Endothelialized biological heart valve prostheses in the non-human primate model.

OBJECTIVE: The main disadvantage of implanted cardiac valve bioprostheses remains primarily tissue failure due to calcification. Coating of bioprostheses with viable autologous endothelial cells may delay or even eliminate tissue calcification and subsequent cardiac dysfunction. METHODS: Glutaraldehyde-preserved Hancock bioprostheses (n = 5), pretreated with glutamic acid (8%) and cryopreserved allografts (n = 5) were lined, using endothelial cells harvested from the external jugular vein. Coated specimens were cultivated for 9 days in Medium 199 supplemented with 20% fetal calf serum and basic fibroblast growth factor. Endothelialized grafts were anastomosed into the descending thoracal aorta of adult Chacma baboons. Untreated valve bioprostheses (n = 4) served as controls. Forty days after implantation the prostheses were examined morphologically and immunohistochemically. RESULTS: After implantation endothelialized prostheses showed a positive Factor VIII related antigen reaction by immunohistochemistry on all valve surfaces. Scanning electron microscopy showed confluently lined leaflets with transplanted endothelial cells and displayed cobblestone morphology on all coated allografts. In contrast, the surface of pretreated xenograft valves revealed uncoated areas with platelet and leucocyte aggregates. No endothelium was observed on the leaflets of untreated controls 40 days after implantation. CONCLUSION: In vitro endothelialization of cardiac valve bioprostheses with autologous endothelial cells is possible. The newly created endothelium is shear stress resistant and the antithrombotic as well as the antiaggregatory capacity of the transplanted cells were retained. Lining with autologous endothelial cells could improve the durability and clinical outcome of biological valve prostheses.

Animals↗
PubMed2002

The utility of lockout valve reservoirs in preventing autoinflation in penile prostheses.

INTRODUCTION: Autoinflation is a troublesome complication following penile prosthesis placement that may be potentiated by prevesical scarring following radical prostatectomy. We evaluated the frequency of autoinflation and other complications following penile prosthesis placement in radical prostatectomy patients and controls as a surrogate to establishing the utility of lockout reservoirs in preventing autoinflation. METHODS: 139 prostheses (including 14 with lockout reservoirs) were placed in 132 men (including 35 post-prostatectomy patients) over a 5(1/2) year period at our institution. Outcomes assessed include postoperative complications and the need for revision or replacement of the prosthesis. Multivariable regression analysis was used to determine the association of patient, device-specific, and perioperative characteristics with these outcomes. RESULTS: There was no difference in the postoperative complication and re-operation rates between post-prostatectomy patients and controls (both p > 0.77). The incidence of autoinflation in post-prostatectomy patients and controls was 3% and 5%, respectively (p > 0.99). Patients with prior prostheses were 3 times as likely to develop a postoperative complication or require prosthesis revision (p = 0.02). CONCLUSION: Penile prostheses are well tolerated in post-prostatectomy patients with comparable outcomes to those men with organic erectile dysfunction. The frequency of autoinflation does not appear to be increased in post-prostatectomy patients. Initial results with the lockout valve reservoir in preventing autoinflation are encouraging though additional study is warranted to justify their routine use.

Aged↗
PubMed1995

Accuracy of implant-supported prostheses in the edentulous jaw: analysis of precision of fit between cast gold-alloy frameworks and master casts by means of a three-dimensional photogrammetric technique.

Distortions of 15 routine implant-supported prostheses were measured in relation to the master casts after completion by means of a 3-dimensional (3-D) photogrammetric technique. All prostheses were designed as one-piece gold-alloy castings with resin teeth. Five of the prostheses were placed in the edentulous maxilla, and the remaining were placed in the lower jaw. Distortion of the cylinders was mostly observed in the horizontal plane (x- and y-axis) while the vertical aspect seemed to be more stable. The mean 3-D center point distortion was 42 (SD 15) and 74 (SD 38) microns for the upper and lower jaws, respectively. The measurements revealed a range of 3-D center point distortion from 16 to 80 and 15 to 165 microns for the different jaws, respectively. The corresponding 3-D mean angular distortion of the cylinders was 51 (SD 35) microns in lower and 70 (SD 75) microns in the upper jaws. A correlation was found between 3-D center point distortion and the width as well as the curvature of the implant arch, indicating more displacement the wider and the more curved the arch was. The 3-D center point distortion was also significantly higher in the upper jaws which could possibly be explained by the curvature of the implant arch and higher numbers of implants in the upper jaws. Further problems with the fit of upper jaw castings could be related to more alloy in the castings and poor alignment of implants.

Dental Prosthesis Design↗
PubMed1997

The use of implant-supported titanium prostheses for treatment of periodontally compromised patients including functional and orthodontic therapy. Report of 2 cases.

Due to its corrosion resistance and biocompatibility, titanium appears to be an alternative material for implant-supported restorations. However, due to technological difficulties, the clinical application of titanium in implant restorations has been limited. Only after recent progress in technology could the clinical use of ceramo-metal titanium restorations be recommended. The therapeutic repertoire for treating patients with missing teeth has been significantly expanded by modern implant methods. Osseointegrated prostheses have become an integral part of restorative therapy also for periodontally compromised dentitions. This article presents 2 case reports for the use of ceramo-metal implant-supported titanium cast prostheses for restorative treatment of periodontally compromised patients requiring comprehensive treatment involving periodontal, functional, orthodontic and prosthodontic therapy. Favourable clinical results have been obtained and a complication-free service of these reconstructions has been documented throughout a 12- to 24-month observation period. These observations suggest that implant-supported ceramo-metal titanium prostheses may be a valuable part of restorative therapy for periodontally compromised dentitions in that they facilitate restorations with optimal biocompatibility. However, controlled clinical studies are needed to establish the long-term serviceability of these titanium restorations.

Aged↗
PubMed2001

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

In 123 patients, 339 implants were connected to 313 teeth by means of fixed partial prostheses (test) and followed up for 1.5-15 years (mean: 6.5). In another ad random selected 123 patients, 329 implants were connected to each other by means of 123 freestanding fixed partial prostheses (control) and were followed up for 1.3-14.5 years (mean: 6.2). The aim of this study was to compare both treatment modalities with each other based on implant, tooth and prosthesis complications. The cumulative implant success, based on implant immobility and/or lack of implant fractures after loading, in the test and control groups amounted to 95% and 98.5%, respectively. Although in the test group 10 implants versus only 1 in the control group failed, a regression analysis of the survival data, based on the cox proportional hazards model, revealed no significant difference. In the test group periapical lesions (3.5%), tooth fracture (0.6%) and tooth extraction due to fatal decay or periodontitis (1%) were observed, besides tooth intrusion (3.4%) and crown cement failure (8%). Framework fracture occurred in 3 patients. In the control group, only 2 abutment screws fractured. The treatment of partial edentulism by means of oral implants was beneficial for our patients. Because of a clear tendency of more implant failures (mobility or fractures) and tooth complications in the tooth-implant connected prostheses, the freestanding solution is the primary option to be considered. To avoid intrusion of abutment teeth, the connection, if made, should be completely rigid.

Adult↗
PubMed2002

Bone level changes proximal to oral implants supporting fixed partial prostheses.

The success of oral implant treatment relies on the presence and maintenance of bone adjacent to implants. The monitoring of radiographic bone level changes provides valuable insight into the longevity of oral implants. The purpose of this study was to measure radiographic bone level changes proximal (mesial and distal) to Brånemark System) implants (Nobel Biocare AB, Göteborg, Sweden) supporting fixed partial prostheses. Measurements were used to determine mean bone loss for the first year of loading by the prosthesis and the mean annual bone loss for subsequent years. These results were then compared and contrasted with various characteristics of the individuals, treatment, and treatment outcomes. Fifty-five subjects with 69 fixed partial prostheses supported by 160 implants were followed over a 1 to 12-year period. A mean bone loss of 0.33 mm (SD 0.59) was measured for the first year of loading and a mean annual bone loss of 0.00 mm (SD 0.11) after the first year. The radiographic bone loss calculated for implants at the first year of loading was positively correlated with the mean annual bone loss thereafter. Males, younger individuals and those implants supporting distal extension prostheses lost significantly more bone in the first year of loading. Larger numbers of implants followed for longer periods of time are needed to further explore the effects of various aspects of treatment on bone loss.

Adult↗
PubMed2002

The effects of fixed and removable implant-stabilised prostheses on posterior mandibular residual ridge resorption.

This study investigated the change over time in the area of the posterior mandibular residual ridge in patients wearing either i) mandibular overdentures stabilised by two implants (Brånemark System; Nobel Biocare, Göteborg, Sweden) connected by a bar, or ii) mandibular fixed cantilever prostheses stabilised on five or six implants. Proportional measurements were made in order to compare the area of the residual ridge with an area of bone uninfluenced by resorption. Measurements were made by digitising tracings of panoramic radiographs that were taken shortly after implant insertion and up to seven years later. With the use of overdentures, the posterior bone area index reduced by a mean of 1.1% per annum, while a mean bone area index increase of 1.6% per annum was demonstrated in association with fixed prostheses. A multiple linear regression model was fitted to predict the change in posterior area from type of prosthesis, gender, age, years of edentulism and initial height of the mandible. The model was only significant for initial height of mandible (P = 0.04) and type of prosthesis (P = 0.0001). In conclusion, patients rehabilitated with implant-stabilised mandibular overdentures demonstrated low rates of posterior mandibular residual ridge resorption, while patients rehabilitated with implant-stabilised mandibular fixed cantilever prostheses demonstrated bone apposition in the same area.

Adult↗
PubMed1998

A prospective study of speech and voice rehabilitation after total laryngectomy with the low-resistance Groningen, Nijdam and Provox voice prostheses.

In a prospective study the Groningen, Nijdam, and Provox voice prostheses were evaluated with respect to speech and voice rehabilitation. At approximately 1, 4, and 10 months after operation, patients were submitted to a standardized speaking task to evaluate phonatory skills (phrase length, phonation duration, dynamics on tone, dynamics on sentence, speech rate and availability of sound), speech quality (fluency and overall intelligibility), voice quality and stoma technique (stoma noise). Tracheoesophageal speech rehabilitation proved to be successful in 94-100% of patients, as measured at approximately 10 months after operation. Furthermore, no significant overall differences were found between the three prostheses. There was a significant improvement in time for speech rate and stoma noise. As for the time effects (e.g. improvement in performance over time) no differences between the three prostheses were found.

Humans↗
PubMed1999

Microbial colonization of silicone voice prostheses used in laryngectomized patients.

The aim of this study was to identify the microbial colonization of dysfunctioning voice prostheses in laryngectomized patients and determine the influence of patient radiation therapy on prosthesis life span. In a 40-month period, 257 outpatient voice prosthesis replacements were carried out in a laryngectomized group of 31 patients. The voice prostheses were all removed from the tracheo-oesophageal fistula after dysfunctioning of the prosthesis. Of the replaced prostheses 183 were cultured. The microbial cultures showed a predominant colonization with Candida albicans and commensal oral microflora. Radiation therapy induced xerostomia shortened the lifetime of the first inserted prosthesis in particular.

Adult↗
PubMed2001

Treatment need for fixed metal ceramic bridge prostheses in patients treated by dental students in 1984-1996.

Even if implant therapy is very common nowadays, treatment with conventional fixed bridge prosthesis still has indications and cannot be forgotten. Because of improved dental health more teeth can be preserved and more fixed prostheses are prepared also for the elderly. The aim of this study was to discuss the future of treatment need in fixed metal ceramic bridge prostheses based on the analysis of distribution of pontics in dentition in four different age groups during the years 1984-1996. Data were collected from the patient files. The numbers of upper lateral incisors, upper first premolars and lower first molars were analysed in years 1984-1987, 1988-1992 and 1993-1996 between and within age groups of under 34, 35-49, 50-64 years and over 65 years. As a conclusion, in the future the treatment need for fixed bridge prostheses will be highest among patients over 50 years and their most replaced teeth are, besides lower first molars, the upper first premolars.

Adult↗
PubMed2000

Modeling lipid uptake in expanded polytetrafluoroethylene vascular prostheses and its effects on mechanical properties.

The radial transport across the wall of expanded polytetrafluoroethylene (ePTFE) arterial prostheses has a significant effect on lipid uptake observed in prostheses implanted in humans, which has been postulated to be one of the causes associated with implant failure. The goal of this study was to stimulate radial transport on a lipidic dispersion across the wall of an ePTFE prosthesis and investigate its effects on the circumferential mechanical properties of the prosthesis. An in vitro model was developed to simulate the lipidic radial transport across the wall. Lipids contained in a phosphatidylcholine dispersion were used as the transported molecules. Lipid concentration profiles were obtained after exposing commercial ePTFE prostheses to various transmural pressure and/or lipidic concentration gradients. Phospholipids gradually accumulated up to the external reinforcing wrap of the prosthesis, which clearly acted as a rigid barrier against lipid infiltration. Tensile tests performed on the virgin samples showed that the wrap was much more rigid than the microporous part of the prosthesis. After the lipid simulation, the rigidity of the wrap decreased with respect to what was observed for the virgin prosthesis. Finally, some clinical implications of this phenomena are discussed.

Biocompatible Materials↗