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PubMed1989

Infections in genitourinary prostheses.

During the past two decades, the use of implantable prostheses has experienced exponential growth. In urology, penile prostheses have been especially popular. Although many mechanical problems have been reported, the most disastrous complication is infection, which usually mandates prosthesis removal and often leads to severe disability or loss of function of the organ in which the prosthesis was implanted. The author reviews the pathogenesis, microbiology, diagnosis, and treatment of genitourinary prosthesis infections.

Female↗

PubMed1989

Infections of genitourinary prostheses.

Infections of penile prostheses and artificial urinary sphincters are relatively rare events. Most infections are due to gram-positive bacteria such as S. epidermidis or gram-negative enteric bacteria. Most commonly, infection begins at the time of implantation, although the hematogenous route has been documented. Signs and symptoms of prosthesis infection may be obvious or subtle. Treatment of infected prostheses usually requires removal, although successful salvage procedures have been described. Prevention of infection through proper antibiotic coverage and careful attention to sterile technique results in acceptably low infection rates.

Bacterial Infections↗

PubMed1989

Smooth vs. rough: an 8-year survey of mammary prostheses.

One-hundred and seventy patients (124 augmentations and 46 reconstructions) were followed for 8 post-operative years. Ninety patients received the "standard" smooth silicone mammary prosthesis, and 80 patients received a polyurethane-covered prosthesis. The longest follow-up was 4 years and the shortest was 1 year, with the average just over 2 years. Six types of complications were registered, with three attributed to implant design (wrinkles, draping, capsules) and three to the operator or surgery (infection, hematoma, extrusion). Firm capsule formation was considered a complication only if another intervention (reoperation, closed capsulotomy, etc.) was recommended by the surgeon or requested by the patient. Ninety-six percent of the patients with polyurethane prostheses had a satisfactory (grade II) or better than satisfactory (grade IA or IB) result, whereas 72 percent of the patients with a standard silicone-gel prosthesis achieved a satisfactory (grade II) or better than satisfactory (grade IA or IB) result. Technical details for use of polyurethane prostheses are given, as well as complications inherent to the polyurethane-covered implant.

Adult↗

PubMedDate not supplied

Improved textured surfaces for implantable prostheses.

Textured surfaces have been shown to reduce scar tissue formation around implanted prostheses compared with identical smooth surface controls in applications such as compliance chambers for artificial heart systems. The authors have developed and evaluated alternative textured surfaces to the polyester velour surface that has been used on those devices. These new textured surfaces are fabricated with materials known to provoke a diminished tissue response compared with polyester fibers. Two new textured surfaces have been examined: a surface composed of extruded 25 micron diameter polyurethane fibrils (PF) woven into a fabric, and an integrally textured silicone rubber surface (TS) with nonfibril geometry applicable to silicone rubber implants such as mammary prostheses. In both cases, tissue fixation to the textured surface depends primarily on mechanical interdigitation with the complicated surface morphology of the implant rather than on chemical bonding. Two types of control were employed: polyester velour fabric (PV) as a textured surface, and smooth silicone rubber (SS). Each surface was first characterized with scanning electron microscopy (SEM), and test specimens consisting of 1 cm diameter by 1 mm thickness disks were then prepared and implanted subcutaneously in a series of 16 adult New Zealand white rabbits. After 8 weeks the samples were explanted and histologic sections prepared for analysis. In all cases a thin, organized tissue capsule surrounded the implant. While the tissue capsule on average was thinner surrounding the textured surface implants, variations in the individual host response were more significant. Tissue attachment was minimal with SS, present with PF, and greatest with TS and PV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Comparison of replacement prostheses for segmental defects of bone. Different porous coatings for extracortical fixation.

The extent of extracortical bone-bridging and ingrowth into porous-coated prostheses for the stabilization of segmental defects was studied in a canine model. Initial fixation of the implant was achieved using bone cement. Autogenous bone grafts were applied over the porous-coated segmental portion of the prosthesis to stimulate the ingrowth and formation of bone. At twelve weeks, bone-bridging and ingrowth occurred uniformly in both the titanium fibermesh and the cobalt-chromium-molybdenum beaded prostheses. Maximum formation of osseous tissue over the implants occurred at two to four weeks. More bone formed in the posterior aspect of the prosthesis. At twelve weeks, 26 per cent of the porous space of the titanium fibermesh prosthesis and 47 per cent of the porous space of the cobalt-chromium-molybdenum beaded prosthesis were filled with bone. The torsional strength and stiffness of the prosthetic midsection that contained a conical coupling joint were increased significantly due to bone-bridging and ingrowth. The cortical bone that was apposed to the segmental prosthesis showed an increase in porosity. The use of bone cement did not appear to impede new-bone formation extracortically. The initial stability of the implant and the application of sufficient autogenous bone grafts are two important factors that contribute to the ultimate stable fixation of an implant by extracortical bone formation.

Animals↗

PubMed1988

[Movements of stapes-piston prostheses in changes in static air pressure].

The displacements of stapes piston prostheses, induced by variations of static air pressure from 0 to +/- 400 mm H2O, were examined in 9 temporal bone preparations by a microscopic measuring method. In the normal middle ear, the gliding incudo-malleal joint, serving as a protective mechanism, confined these movements to a mean of 232 microns. These in- and excursions could exceed 0.5 mm, however, with an ankylosed incudo-malleal joint. Arthrosis of this joint is not rare in otosclerosis. In view of these excessive displacements, compared to inner ear dimensions, piston prostheses should always dip into the vestibulum in the lower half of the footplate, far from endolymphatic membranes. A simple technique may intraoperatively reveal the gliding or ankylosed condition of incudo-malleal joint surfaces, prior to adapting the length of the prosthesis.

Acoustic Impedance Tests↗

PubMed1985

Intraoperative consultation for surgery of the genitalia and genitourinary prostheses.

Patients with genitourinary prostheses, especially the hydraulic variety, will be encountered with increasing frequency in the future and present special problems to the urologist who is called in for intraoperative consultation. Knowledge of the design and operation of these devices, as well as certain operative principles unique to these prostheses, permits the urologist to deal effectively with these situations.

Female↗

PubMed1985

[Hydraulic penile prostheses in the surgery of impotence. Our experience in 20 cases with a 2-year follow-up].

The authors report their experience of the implantation of inflatable penile prostheses in the surgical management of impotence. They have implanted twenty prostheses with a followup of two years to three months. The overall results are very satisfactory in terms of the quality of the sexual life of the couple (85%). On the other hand, the postoperative morbidity rate is high, with 40% of complications including 20% requiring reoperation.

Adult↗

PubMedDate not supplied

Psychoacoustic evaluation of present prostheses.

A battery of psychoacoustic tests, designed to specify auditory discriminations possible with present, single-channel auditory prostheses, was administered successfully to 12 of the 13 subjects. While no subject was able to perform all discriminations required by this battery of tests, there was no discrimination that at least one subject did not perform successfully. The typical subject could 1) discriminate intensity differences within normal limits for frequencies below 1000 Hz; 2) discriminate frequency differences quite normally at 125 and 250 Hz, but not at all at 1000 or 2000 Hz; 3) discriminate differences in signal duration, temporal patterning (rhythm), and spectrum (e.g., tone vs narrow-band noise); and 4) discriminate between pairs of synthesized vowel-like sounds. The results of masking experiments could only be interpreted in terms of intensity discrimination. Several subjects were able to relate stimulus intensity to loudness for low-frequency sounds; and they could relate stimulus frequency to pitch for signals below 25 Hz. The intelligibility of the subjects' speech was found to improve when their prostheses were activated.

Auditory Threshold↗

PubMed1984

[Hematogenous infection of prostheses in man and in an animal model].

A case is reported which suggests a hematogenous route of infection in orthopedic prostheses. Furthermore, in a foreign body animal model the hypothesis was tested that implanted prostheses may be endangered during episodes of bacteremia. These experiments confirm the clinical impression that foreign bodies can be selectively infected during experimental bacteremia with Staphylococcus aureus.

Aged↗

PubMed1982

Experience with penile prostheses in the treatment of impotence in diabetic men.

Increasing use of penile prostheses to treat impotence in diabetic men warrants a detailed assessment of functional and subjective outcomes within this group. This study uses record review and patient-partner questionnaire techniques to examine this population and evaluate postoperative satisfaction in terms of changes in patterns of sexual activity, health status, and complication rates. The satisfaction rates among patients and partners were 81% and 83%, respectively. Frequency of sexual activity was increased, and physical enjoyment was improved among satisfied recipients. Most postoperative complications were treatable and led to dissatisfaction only if they were irreparable. Most prostheses are therefore being used successfully. We recommend that impotent diabetic men be informed of the availability of prosthetic implants.

Adult↗

PubMed1994

[Interactions of electromagnetic fields produced by magnetic resonance with prostheses and ferromagnetic materials].

This paper accounts for coupling modes and effects that NMR-induced electromagnetic fields (B0, dB/dt, RF) produce when interacting with prostheses and ferromagnetic materials. As for prostheses specifically, the paper reports an original contribution: an in vitro test performed on the NMR equipment mod. SISCO SIS 200/183 for research purposes installed at the Istituto Superiore di Sanità. Scope of this study was the evaluation of effects and malfunctionings induced by the above-mentioned electromagnetic fields on pacemakers inside a human trunk simulator exposed to NMR field intensity.

Electromagnetic Fields↗

PubMed1995

[Macroscopic, histologic and ultrastructural study of 89 prostheses of anterior cruciate ligament excised because of prosthesis failure].

PURPOSE OF THE STUDY: This study concerns the etiology of failed synthetic anterior cruciate ligament (ACL) prostheses, and attempts to identify the primary mechanisms that lead to their premature rupture. MATERIAL AND METHODS: A total of 89 failed and surgically excised ACL prostheses were retrieved from young and active patients (27 +/- 7 years) at various orthopaedic centres in France. Their average duration of implantation was 34 +/- 24 months. They were examined macroscopically, histologically and by scanning electron microscopy (SEM) to determine the model, the manufacturer, the surgical technique used at implantation, the extent of healing, the site of rupture, as well as the morphology of the damage fibers. RESULTS: Seventy two of these explants represented 6 different models. While all 6 were fabricated from polyester fibres, each had a different textile construction, and each were associated with a unique healing and mechanical response in vivo. SEM observations confirmed that abrasion of the textile fibres were a phenomenon common to all models, and were the primary cause of prosthesis failure. Such wear zones were particularly prevalent at the exit of the tibial tunnel and around the femoral condyle. Collagenic infiltration into the synthetic ACL was poorly organized and unpredictable. It did not increase with the duration of implantation. In fact in certain models, it appeared to have caused deterioration and fraying of the textile structure rather than serving as a reinforcing matrix around the prosthesis. DISCUSSION: A synthetic ACL prosthesis is to be preferred for patients who do not have tissue available for autologous ligamentoplasty. Yet none of the synthetic devices examined in the present study were capable of stabilizing the knee over the long term. Among the factors that influenced their failure we found that the three most common mechanisms were flat abrasion against an osseous surface, flexural and rotational fatigue of the fibres, and loss of integrity of the textile structure due to unpredictable tissue infiltration during healing. CONCLUSION: The results of the present study show that none of the current models succeed in replacing the natural ACL. Future improvements may be achieved by developing surgical procedures for implantation combined with a prosthesis made from fibres and textile structures which are more abrasion resistant and promote predictable and controlled tissue infiltration.

Adult↗

PubMed1996

[Abdominal wall prostheses. Biomechanic and histological study].

The best prosthetic material is one which provides the best mechanical resistance with the best biological tolerance. In order to assess the mechanical and histological properties of abdominal wall prostheses, we performed experimental tests in animal models comparing four materials: polypropylene, dacron, polyglactine 910 and a dacron-polyglactine 910 composite. One hundred thirty rabbits were used including 10 controls and 120 test animals. A medial laparotomy was closed with an antemuscular aponevrotic prosthesis in the test animals. Animals were sacrificed at one, two and three months after the operation. Abdominal wall and prosthesis samples were tested to determine resistance to pressure and extension, deformability and elasticity. Histology tests were also done to determine resistance quality and biological tolerance. Dacron was tolerated best and was less resistant than polypropylene, though resistance was satisfactory. There was no advantage with polyglactine compared with non-resorbable prostheses; its only indication would be a septic site. The composite material tested had a resistance comparable with that of dacron but was less well tolerated.

Abdominal Muscles↗

PubMed1976

A comparison of four models of total knee-replacement prostheses.

Twenty-nine knees with unicondylar, sixty-four with duocondylar, fifty with Guepar, and fifty with geometric prostheses were studied. The follow-up ranged from two to three and one-half years. The unicondylar prosthesis was used in the mildest cases and gave the least complications, but the quality of results was not superior to that achieved with the other prostheses. The duocondylar model was best suited for knees with rheumatoid arthritis and mild deformity. The geometric prosthesis was the best condylar prosthesis for osteoarthritis with moderate to severe deformity, but gave the worst results in knees with rheumatoid arthritis. The Guepar prosthesis was used in the worst knees and gave the best results, but it had the highest infection rate and was the most difficult to salvage. A radiolucency was observed in about 60 per cent of the condylar replacements around the tibial component and in 45 per cent of the Geupar replacements around the femoral component. The significance of this cannot yet be determined but it suggest that the fixation may not be ideal. In all types, residual pain was most frequently attributed to the patellar compartment. Patellectomy was not a solution.

Aged↗

PubMed1984

Aerodynamic properties of four tracheoesophageal puncture prostheses.

Airway resistance calculations were completed for two tracheoesophageal puncture prostheses (American V. Mueller Blom-Singer Voice Prosthesis and BIVONA Low Resistance Voice Prosthesis), which have recently become available on a commercial basis. These calculations were compared with those made previously for two, existing prostheses: the Blom-Singer duckbill and the Panje Voice Button. Substantial differences in airway resistance properties exist among these four devices. BIVONA Low Resistance devices exhibited the lowest resistance (less than 50 cm H2O/liters per second [LPS]); Panje Voice Buttons exhibited the highest (180 to 200 cm H2O/LPS); and Blom-Singer devices exhibited intermediate values (110 to 125 cm H2O/LPS) of opposition.

Air↗

PubMed1986

Oropharynx decontamination preventing Candida vegetation on voice prostheses.

Candida vegetations found in silicone voice prostheses used in postlaryngectomy voice rehabilitation are associated with prosthesis dysfunction. Selective oropharyngeal decontamination with amphotericin B lozenges resulted in sharp decrease of oropharyngeal Candida concentrations with a subsequent reduction of yeast colonization on voice prostheses and in tracheoesophageal fistula in ten patients. A case report suggests that this selective oropharyngeal decontamination can prolong the device's lifetime.

Administration, Oral↗

PubMed1979

Current arterial prostheses. Experimental evaluation by implantation in the carotid and circumflex coronary arteries of the dog.

Five types of 4-mm diameter arterial prostheses (three Dacron, one expanded Teflon, one preserved umbilical vein) were studied in the dog to assess graft thrombogenicity. Separate experiments involving six hours of controlled blood flow, one-week carotid implantation, and aortocoronary implantation were performed. In general, graft thrombogenicity derived from controlled flow study was more predictive of a graft's long-term implantation success than were one-week implantation results. In order of increasing thrombogenicity, we ranked grafts studied as follows: noncrimped Dacron, expanded Teflon, crimped Dacron, umbilical vein. Results of 19 experimental left coronary artery implantations using Dacron or Teflon prostheses are reported that indicate grafts with low measured thrombogenicity are most likely to succeed in this site. Data presented in this report suggest there is reason to evaluate noncrimped, kink-resistant, porous Dacron grafts for use both in the left coronary artery and below the knee when there is compelling clinical indication and no autogenous vessels are available.

Animals↗