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PubMed1994

Surgical closure of the patent ductus arteriosus with an intravascular prosthesis: clinical experience.

The authors developed a new prosthesis for patent ductus arteriosus (PDA) closure, using a delivery device inserted through the main pulmonary artery (MPA) avoiding ductal dissection and use of cardiopulmonary bypass. The prosthesis was inserted in 19 consecutive patients between 1985 and 1992. They have been followed for a mean of 4.8 years (minimum 30 days, maximum 7.5 years). There were 14 women (72%) and the average age was 11 years (16 months to 38 years). All patients presented with pulmonary hypertension (4 severe, 5 moderate, and 10 mild). Simultaneous surgical procedures for congenital heart disease were performed in two cases. One patient had a diffuse calcified PDA. The average diameter of the inserted prosthesis was 7.5 mm (3.5 to 12.5 mm). Neither hemorrhage nor prosthesis dislocation/embolization occurred during the implantation or in the postoperative period. In a newborn (30 days) with severe cardiomegaly and thin MPA, we decided to ligate the ductus. Chronic cor pulmonale contributed to death in one patient 3.7 years after operation. The remaining patients recovered well, without clinical evidence of residual shunt. Therefore, we recommend the use of this new prosthesis for PDA closure in cases of large ductus or ductus complicated with calcification, pulmonary hypertension, and when associated open heart surgery is required.

Adolescent↗

PubMed1984

Torsion and bending imposed on a new anterior cruciate ligament prosthesis during knee flexion: an evaluation method.

A new composite prosthesis was recently proposed for the anterior cruciate ligament. It is implanted in the femur and the tibia through two anchoring channels. Its intra-articular portion, composed of a fiber mesh sheath wrapped around a silicone rubber cylindrical core, reproduces satisfactorily the ligament response in tension. However, the prosthesis does not only undergo elongation. In addition, it is submitted to torsion in its intra-articular portion and bending at its ends. This paper presents a new method to evaluate these two types of deformations throughout a knee flexion by means of a geometric model of the implanted prosthesis. Input data originate from two sources: (i) a three-dimensional anatomic topology of the knee joint in full extension, providing the localization of the prosthesis anchoring channels, and ii) a kinematic model of the knee describing the motion of these anchoring channels during a physiological flexion of the knee joint. The evaluation method is independent of the way input data are obtained. This method, applied to a right cadaveric knee, shows that the orientation of the anchoring channels has a large effect on the extent of torsion and bending applied to the implanted prosthesis throughout a knee flexion, especially on the femoral side. The study suggests also the best choice for the anchoring channel axes orientation.

Biomechanical Phenomena↗

PubMed1976

Malfunction of Björk-Shiley valve prosthesis in tricuspid position.

Eight months after triple valve replacement with Björk-Shiley tilting disc valves a patient developed symptoms and signs suggesting malfunction of the prosthesis in the tricuspid position. This was confirmed by echocardiography and angiocardiography, and at operation thedisc of the prosthesis was found to be stuck half-open by fibrin and clot. A further 11 patients with the same tupe of prosthesis in the triscupid position were then studied by phonocardiography and echocardiography. In one of these the prosthesis was found to be stuck and this was confirmed by angiocardiography and surgery. These 2 cases are reported in detail and the findings in the other 10 are discussed. The implications of this high incidence of malfunction of the Björk-Shiley prosthesis in the tricuspid position are considered. Echocardiography appears to be essential in the follow-up of such patients.

Adult↗

PubMed2004

A new testis prosthesis material: polymethylmethacrylate.

INTRODUCTION: Silicone has been the standard prosthesis material for the last three decades but new materials are being searched because of the known disadvantages of silicone such as migration and high cost. We wanted to test in rats whether or not polymethylmethacrylate could be an alternative to silicone. MATERIALS AND METHODS: We prepared polymethylmethacrylate and silicone testis prostheses which were similar to testis size of rats. Eleven rats were implanted with polymethylmethacrylate, 11 others were implanted with a silicone prosthesis and sham operation was performed in 10 rats. Three months later the scrotums of the animals were removed with the prosthesis for a quantitative analysis of the chronic inflammation and fibrotic reaction and to measure the thickness of the capsule. RESULT: Rejection and infection were not observed in any of the prosthesis-implanted rats. Both prosthesis groups displayed increased vascularization, hemosiderin accumulation and fibrotic and hyalinized tissue formation that replaced the muscle. Chronic inflammation was measured and found to be higher in the polymethylmethacrylate group and the difference was not found to be significant. The average thicknesses of the capsules around the polymethylmethacrylate and silicone groups were found to be 58.4 and 46.8 microm, respectively, and that difference was not significant again. CONCLUSIONS: In the short term polymethylmethacrylate was equally well tolerated, but the low cost of polymethylmethacrylate made it more advantageous.

Animals↗

PubMed1996

Priapism in sickle cell disease: the case for early implantation of the penile prosthesis.

OBJECTIVES: Recurrent ischemic priapism in sickle cell (SS) patients often leads to impotence. Blockage of venous outflow by sickle cells leads to anoxia of the cavernosal smooth muscle with subsequent replacement of the erectile tissue with dense fibrosis. This study evaluates the efficacy of early penile prosthesis implantation in patients with priapism associated with sickle cells disease. METHODS: Our recent experience includes 6 SS patients with impotence resulting from repeated episodes of priapism and 1 SS patient who suffered penile autoamputation from prolonged tricorporeal low flow priapism. The average age was 26 years. Six patients underwent excision of fibrotic cavernosal sinusoidal tissue and placement of a malleable prosthesis. The autoamputation case was managed with a one-stage penile reconstruction using a forearm free-flap and a two-piece inflatable penile prosthesis. RESULTS: All patients in our series are currently potent. Because of infection, 1 patient required removal and subsequent reinsertion of his prosthesis, and another has required revision. CONCLUSION: Potency in the young SS patient with recurrent episodes of ischemic priapism may best be managed by a penile prosthesis. Early implantation may lessen the psychological trauma of repeated priapisms, and reduce the technical difficulties and complications associated with penile prosthetic insertion in the presence of dense fibrosis.

Adolescent↗

PubMed1997

Transvenous closure of secundum atrial septal defects: preliminary results with a new self-expanding nitinol prosthesis in a swine model.

BACKGROUND: Our purpose was to evaluate a new prosthesis for percutaneous closure of secundum atrial septal defects (ASDs). METHODS AND RESULTS: Percutaneous closure of surgically created fossa ovalis ASD was attempted in 15 minipigs. The mean balloon-stretched ASD diameter was 12.3+/-2.3 mm (range, 10 to 16 mm). The self-expanding prosthesis was braided from 0.005-in Nitinol wires in the shape of two flat buttons with a short connecting waist with a diameter corresponding to that of the defect to be closed. Polyester filling was added to enhance thrombogenicity. Pulmonary arteriography with levo-phase was obtained before placement; immediately after placement; and at 1-week, 1-month, and 3-month follow-ups. Four animals were killed at 1 week, 1 month, and 3 months for histopathological correlation. Three deaths resulted from ventricular fibrillation (one during anesthesia and two during the placement procedure). Successful placement of the prosthesis was achieved in the remaining 12 animals. Overall immediate ASD closure on angiography occurred in 7 of 12 animals (all polyester-filled prostheses). Absent or trace shunt by angiography was present in 11 of 12 devices at 1 week, with the remaining one demonstrating a small shunt. All septal defects were completely closed at 1 month with the exception of one case in which delayed partial dislodgment of an undersized prosthesis into the right atrium had developed. Closure rate at 3 months was 100%. Neoendothelialization and fibrous incorporation of the prosthesis were completed within 1 to 3 months. CONCLUSIONS: Effective and permanent occlusion of secundum ASDs is feasible with a device that offers the advantages of easy placement, self-centering, and repositionability.

Alloys↗

PubMed2006

Impact of prosthesis-patient mismatch on long-term survival in patients with small St Jude Medical mechanical prostheses in the aortic position.

BACKGROUND: The impact of aortic prosthesis-patient mismatch (P-PtM) on long-term survival is unclear. METHODS AND RESULTS: Between 1985 and 2000, 388 patients at Mayo Clinic in Rochester, Minn, underwent aortic valve replacement (AVR) with 19- or 21-mm St Jude Medical prostheses and had transthoracic echocardiography within 1 year after AVR. Mean age of patients was 62+/-13 years; 69% were female. Prosthesis effective orifice area (EOA) was derived from the continuity equation. P-PtM was classified as severe (indexed EOA < or =0.60 cm2/m2), moderate (0.60 cm2/m2 0.85 cm2/m2). P-PtM was severe in 66 patients (17%), moderate in 168 (43%), and not hemodynamically significant in 154 (40%). Patients with severe P-PtM had a significantly larger body surface area (P<0.0001), higher mean gradient (P<0.0001), lower preoperative (P<0.0001) and postoperative (P<0.0001) ejection fractions, and lower stroke volume (P<0.0001) and more often received a 19-mm prosthesis (P=0.0008) than patients with moderate or no hemodynamically significant mismatch. For patients with severe mismatch, 5-year survival rates (72+/-6%) and 8-year survival rates (41+/-8%) were significantly less than for patients with moderate mismatch (80+/-3% and 65+/-5%; P=0.026) or no hemodynamically significant mismatch (85+/-3% and 74+/-5%; P=0.002). On multivariate analysis after adjustment for other predictors of outcome, severe mismatch was associated with higher mortality (hazard ratio 2.18; 95% confidence interval 1.24 to 3.85; P=0.007) and higher incidence of congestive heart failure (hazard ratio 3.1; 95% confidence interval 1.3 to 7.4; P=0.009) than no hemodynamically significant mismatch. CONCLUSIONS: Severe P-PtM is an independent predictor of higher long-term mortality and congestive heart failure in patients with small St Jude Medical aortic valve prostheses. For patients undergoing AVR who are at risk of severe mismatch, every effort should be made to use a larger prosthesis or to consider a prosthesis with a larger EOA.

Aged↗

PubMed1983

Malleus Teflon piston prosthesis.

The malleus Teflon piston prosthesis is very useful to reconstruct the sound conducting mechanism of the middle ear in absent or inadequate incus, congenital malformation of the middle ear, and epitympanic fixation of the incus and/or malleus. It has a thin-walled loop at its upper end to lessen the tendency for ulceration of the overlying drum with an inside diameter of 1 mm to fit around the mid portion of the handle of the malleus at an angle of 30 degrees to the shaft of the prosthesis. There is a cut in the distal part of the loop through which it is snapped onto the handle of the malleus after it is separated from the drum. Examples of the various situations in which this prosthesis has been used will be shown together with the results regarding hearing gain, complications, and other problems. Those situations in which the prosthesis was used in 1972 will be reviewed to give a 10-year follow-up, plus some notable examples of other uses of the prosthesis from other times.

Ear Ossicles↗

PubMed1997

The effect of changing the inertia of a trans-tibial dynamic elastic response prosthesis on the kinematics and ground reaction force patterns.

The aim of this study was to assess, by means of gait analysis, the effect on the gait of a trans-tibial amputee of altering the mass and the moment of inertia of a dynamic elastic response prosthesis. One male amputee was analysed for four to five walking trials at normal and fast cadences, using the VICON system of motion analysis and an AMTI force plate. The kinematic variables of cadence, swing time, single support time and joint angles for the knee and hip on the affected and intact sides were analysed. The ground reaction force was also analysed. The sample size was limited to one as an example to indicate the changes which are possible through simply changing the inertial characteristics. Descriptive statistics are used to demonstrate these changes. Three mass conditions for the prosthesis were analysed m1: 1080g; m2: 1080 + 530g; m3: 1080 + 1460g. The m1 condition is the mass of the prosthesis with no added weight while m2 and m3 were attachments of the same geometrical shape but were made from different materials. It was felt that the large mass range would highlight biomechanical adjustments as a result of its alteration. The effect on selected temporal characteristics were that as the speed increased the cadence changed and the affected side single support times as a percentage of the gait cycle were altered. The effect on the joint angles was also apparent at the hip and knee of both sides. The ground reaction force patterns were similar for all three mass conditions, though the impact peak which was evident in the intact limb was missing, indicating a shock absorbing property in the prosthesis. Clearly, changing the mass and moment of inertia has an effect on the kinematic variables of gait and should be considered when designing a prosthesis.

Artificial Limbs↗

PubMed1994

[Evaluation of maxillary prosthesis for better QOL].

Conventional maxillary prostheses were fabricated for more than 200 cases of postoperative maxillary defect. The maxillary prosthetics could be combined at any time in the course of primary tumor treatment by taking care to start early, fabricating quickly and lightening the prosthesis weight. Of these 200 cases, 104 who had visited during the one year period of 1992, were sent questionnaires for the evaluation of maxillary prosthesis. The questionnaires were composed of subjective and objective evaluations of speech, swallowing, eating and the feeling and duration of usage. Of 98 answers obtained, 94 valid answers were converted into points and analyzed in combination with the classifications of maxillary defect, stroke of mouth opening and the number of residual teeth. As the sizes of maxillary and soft palate defects increased, each point on the evaluations of speech, swallowing, eating, and feeling decreased, except the duration of usage in one day. The stroke of the mouth opening and the number of residual teeth were related to the abilities to swallow and eat. The analysis in this study revealed that early prosthesis fabrication served to enhance the quality of life. The patients, however, took a long time to become skilled in using the prosthesis. To obtain better prosthesis function, it is important (1) to avoid soft palate defects, (2) to minimize gingival and hard palate defects, (3) to make the mouth opening more than 20mm, and (4) to preserve the teeth material as much as possible. On the basis of these results, the author concludes that maxillary prosthetics designed according to our concept greatly enhance the quality of life of patients with postoperative maxillary defects.

Adult↗

PubMed1999

Staphylococcus aureus prosthetic joint infection treated with prosthesis removal and delayed reimplantation arthroplasty.

OBJECTIVE: To estimate in patients with Staphylococcus aureus prosthetic joint infection after total hip arthroplasty (THA) or total knee arthroplasty (TKA) the microorganism-specific cumulative probability of treatment failure after prosthesis removal and delayed reimplantation arthroplasty. PATIENTS AND METHODS: All patients with S aureus THA or TKA infection, according to a strict case definition, who were treated with prosthesis removal and delayed reimplantation arthroplasty at Mayo Clinic Rochester between 1980 and 1991 were identified. The study group comprised patients who were free of infection at the time of reimplantation arthroplasty. This cohort was followed up until treatment failure, infection with another organism, prosthesis removal, death, or loss to follow-up occurred. The Kaplan-Meier survival method was used to estimate the cumulative probability of treatment failure. RESULTS: Among 120 S aureus prosthetic joint infections treated with prosthesis removal during the study period, 38 episodes (22 THA, 16 TKA) in 36 patients met the study inclusion criteria. After a median of 7.4 years (range, 0.9 year-16.4 years) of follow-up, treatment failure occurred in 1 (2.6%) of 38 episodes 1.4 years after reimplantation arthroplasty. The 5-year cumulative probability of treatment failure was 2.8% (95% confidence interval, 0%-8.2%). CONCLUSIONS: These data suggest that prosthesis removal and delayed reimplantation arthroplasty is an effective treatment to limit the recurrence of S aureus prosthetic joint infection, provided there is no evidence of infection at the time of reimplantation arthroplasty.

Adult↗

PubMedDate not supplied

The canine cemented modular total hip prosthesis.

Total hip replacement (THR) is well established as a treatment modality for dogs with noninfectious, nonneoplastic, disabling conditions of the coxofemoral joint. Since the mid 1970s, a fixed-head prosthesis has been used in this procedure. A modular prosthesis, which is based on many of the technical advances found in human prostheses, now is available for use in veterinary medicine. The prosthesis, surgical instrumentation, surgical technique, and clinical results have been evaluated in a prospective study conducted at The Ohio State University's College of Veterinary Medicine. The modular prosthesis provides results equal to or better than the fixed-head prosthesis.

Animals↗

PubMed1992

[Implantation of self-contained non-inflatable penile prosthesis in patients with organic impotence].

Between April, 1988 and August, 1990, the OmniPhase penile prosthesis, a non-inflatable self-contained penile prosthesis, was implanted in 34 patients, aged from 37 years to 79 years, averaging 54.2 years. The etiologies of the impotence were radical surgery for bladder cancer or rectal cancer in 17 patients, diabetes mellitus in 7 patients, vascular abnormality in 3 patients, spinal injury in 2 patients, penile disorders in 2 patients and others in 3 patients. Penile prosthesis was implanted by subcoronal incision under spinal or general anesthesia. Clinical results were evaluated 12 weeks after surgery. Thirty-two patients (94.1%) could have intercourse postoperatively. Eighteen patients (52.9%) were completely satisfied and 14 patients (41.2%) were satisfied, whereas one patient (2.9%) had no improvement and another patient (2.9%) deteriorated. There was no serious complication. However, prosthesis was explanted because of skin erosion in one patient. Pain, which lasted for more than 10 days, was seen in 3 patients (8.8%), penile edema in 11 patients (32.4%), and acute epididymitis in one patient. The obtained results showed that implantation of OmniPhase penile prosthesis is a safe and useful procedure for treatment of organic impotence.

Adult↗

PubMed2000

Distal extension mandibular removable partial denture connected to an anterior fixed implant-supported prosthesis: a clinical report.

This clinical report demonstrates the possibility of achieving positive results with a removable prosthesis connected to an implant-supported fixed prosthesis. Bone quality and quantity at the implant sites are essential requirements for the success of the treatment. The support of the RPD and its connection with the fixed prosthesis creates stability during chewing activity and allows a functional activity similar to that involving an overdenture. The adoption of an occlusal scheme with subocclusion of the fixed prosthesis contacts compared with those of the removable prosthesis, together with the stress-director system of the RPD can be effective factors that decrease the risk of loss of implant integration. Further long-term follow-up studies with a larger patient population are needed to confirm the clinical and biomechanical validity of the prosthetic solution described in this clinical report.

Aged↗

PubMed2000

The floating radial head prosthesis for comminuted radial head fractures: a multicentric study.

We report our experience with the floating radial head prosthesis of Judet for comminuted fractures of the radial head. We present the results in 15 patients with a mean follow-up of 25.2 months. Thirteen prostheses were inserted for acute Mason III fractures of the radial head, and 2 were inserted for chronic problems after radial head fracture. According to the Mayo Elbow Performance Index there were 7 excellent, 3 good, 1 fair and 2 poor results in the group with acute injuries. In this group, one prosthesis was removed after 8 months for severely decreased elbow function. In the group with chronic problems, there were 2 fair results. There were no dislocations or prosthesis fractures. None of the prostheses showed signs of loosening. Three patients in the acute group developed wrist pain, and in one patient in the chronic group, preexisting wrist pain disappeared after insertion of the radial head prosthesis. Our short-term results suggest that the floating radial head prosthesis is a suitable solution for early or delayed treatment of Mason type III fractures, either isolated or associated with more complex injuries.

Adult↗

PubMed1975

A new patella prosthesis. Design and application.

The new patella prosthesis design is based on an anatomical study of 80 arthritic patellas and on the normal patellofemoral contact area under loading in cadaver knees. The metal dome-shaped prosthesis is attached by a central pin. The patellar prosthesis is constructed either of metal or plastic for use in combination with the Hospital for Special Surgery design of total knee prosthesis. Methylmethacrylate is used to supplement the fixation after resection of the abnormal patellar articular surface. The fixation tests gave excellent laboratory results for contact area and stability. The prosthesis has been used in 19 cases with encouraging early results.

Adult↗

PubMed2001

[Disappointing long-term experiences of patients with penile prosthesis].

OBJECTIVE: To describe the long-term experience with the implantation of a penile prosthesis as a last resort treatment for erectile dysfunction. DESIGN: Retrospective and descriptive. METHOD: During the period 1986-1996, 124 men received a penile prosthesis. Basic information was obtained from medical files. Seventy-six men could be traced and were sent a questionnaire. Sixty patients and 44 partners participated in the study. RESULTS: The median time since the implantation was 81.3 months (range: 13-139). The chance of reoperation was 35%. Seventeen percent of the patients and 25% of the spouses regretted the decision to have the implantation. Thirty-one percent no longer used the prosthesis and 15% had never used it. Twenty percent of the patients and 31% of the partners noticed an improvement in their sexual relationship whereas 26% and 23% respectively noticed a decline. Twenty percent of the patients sometimes failed to penetrate despite the prosthesis. Nevertheless, 66% would advise implantation to someone else. Almost 50% of the men reported spontaneous tumescence during sexual arousal. CONCLUSION: After the implantation of a penile prosthesis, the reoperation rate was high, and many patients and their partners were dissatisfied with their sexual relationship despite regaining a functional erection. Implantation requires thorough sexological counselling both before and after the operation.

Adult↗

PubMed1975

Femoral head replacement with the christiansen endoprosthesis. A follow-up study, and a report on 175 arthroplasties with the present model of the prosthesis with acrylic cement fixation.

A review of the experience gained after 300 consecutive femoral head replacements using the Christiansen Endoprosthesis is given. The arthroplasties were performed mainly for fresh, displaced femoral neck fractures in elderly patients and for complications of these fractures, such as pseudarthrosis and aseptic necrosis. The patient material is divided into 2 groups. Group 1: Patients who had the older prosthesis model with plastic capitulum pieces inserted, and Group 2: Patients who had the present prosthesis model with metal-capped capitulum pieces inserted together with acrylic cement fixation. While the results initially were promising in the first group, a longer follow-up was very disappointing. Wear of the plastic material resulted in a pronounced foreign body synovitis with pain and reduced mobility. Furthermore, there were osteolysis and fractures related to the prosthesis in a great number of patients observed for more than 2 years. This led to a change in the construction of the capitulum piece of the prosthesis which was now equipped with a metal cap and to the use of acrylic cement fixation of the shaft piece. The follow-up results in these patients (Group 2) have been most encouraging, with absence of the above-mentioned complications after up to 6 years' observation. The mortality and complications encountered are discussed. It is concluded that femoral head replacement on the indications outlined, using the present prosthesis model with acrylic cement fixation, represents a very good alternative in the treatment of displaced femoral neck fractures and their complications.

Acrylates↗