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PubMed1993

The compressible silicone rubber prosthesis in temporomandibular joint disease.

An alternative technique for temporomandibular joint arthroplasty is described, in which the mandibular condyle is replaced by a soft compressible silicone rubber prosthesis. A modified Nicolle-Calnan metacarpo-phalangeal joint prosthesis was used to reconstruct 31 joints in 24 patients. Results suggest that in those patients where there has been no loss of the prosthesis, function continues to be markedly improved when compared with the pre-operative condition. Painful symptoms were relieved in cases of specific joint pathology but the technique was of little value in the management of dysfunctional pain when radiographic evidence of joint pathology was absent. A specifically designed TMJ prosthesis of this type may be a useful addition to the surgeon's armamentarium.

Adolescent↗
PubMed1995

Evaluation of temporomandibular joint prostheses: review of the literature from 1946 to 1994 and implications for future prosthesis designs.

PURPOSE: This article describes the useful elements of applied temporomandibular joint (TMJ) prostheses and discusses the factors necessary to be addressed in an appropriate TMJ prostheses design. MATERIALS AND METHODS: Information about TMJ prostheses was gathered by a literature search. Only designs with the primary intention of true joint replacement were selected. The designs were divided in fossa-eminence, condylar, and total joint replacements, which are reviewed separately. RESULTS: A fossa-eminence prosthesis can be fixed by a metal plate screwed to the root of the zygomatic arch. A condylar prosthesis can be fixed by a metal plate screwed to the mandibular ramus and fitted by bending the plate or using different sizes. All reviewed designs resulted in a loss of translational movements of the mandible, especially in an anterior direction. Although the recent designs use the same materials as are used in hip and knee joint prostheses, the wear properties of the existing TMJ prostheses are still unknown. CONCLUSIONS: A future prosthesis must imitate the anterior movement of the mandible when the mouth is opened and also allow some mediolateral movement. The fitting to the skull is still a major problem, as is the combination of the required motions and low wear rates. To confirm good clinical performance of a new TMJ prosthesis, long-term follow-up studies are necessary.

Evaluation Studies as Topic↗
PubMed2006

Prosthesis survivorship and clinical outcome of the Austin Moore hemiarthroplasty: An 8-year mean follow-up of a consecutive series of 500 patients.

The results of a consecutive series of 500 patients treated with Austin Moore hemiarthroplasty prosthesis are reported. The range of follow-up was from 5-12 years and the mean was 8 years. Only 10 patients were lost to follow-up and 398 (81%) patients died within the follow-up period. The mean age of the patient population was 82 years, and 85% were women. The cumulative survivorship of the prosthesis was calculated at 94% (95% CI 90-96%) at 5 years and 83% (95% CI 65-94%) at 12 years. A total of 66 secondary operations of any type were required in 46 (9%) patients. Revision of the Austin Moore prosthesis was performed in 23 cases (5%). Of the long-term survivors contacted for follow-up, 66 (81%) had no pain or minimal pain, whilst 5 (6%) reported constant pain in the hip. The revision rates in our series were higher for younger patients, those from their own home and with good pre-fracture mobility and mental function. For the frail elderly with a displaced intracapsular fracture this prosthesis can still be recommended. This paper presents the largest consecutive series, with the longest follow-up, currently available.

Aged↗
PubMed2005

Voice restoration with the advantage tracheoesophageal voice prosthesis.

OBJECTIVES: To determine whether the Blom-Singer indwelling Advantage tracheoesophageal voice prosthesis (TEP) extends prosthesis life span significantly in patients with documented premature device failure due to fungal colonization. STUDY DESIGN AND SETTING: Data were collected in a prospective manner on a total of 42 standard indwelling TEP users who exhibited early device failure, that is, between 2 weeks and 6 months, due to fungal colonization of the flap valve despite appropriate use of oral antifungal agents. There were 29 men and 13 women, whose ages ranged from 36 years 10 months to 86 years 8 months. METHODS: Baseline data were derived from the average number of days 3 previous standard indwelling prostheses functioned before leaking. An Advantage indwelling TEP was placed after the third change, oral antifungal agents stopped, and routine care implemented, that is, flush and brush the device in situ twice each day. Each participant was assigned to 1 of 3 groups. Group 1 had device failure equal to or less than 2 months (n = 12). Group 2 had device failure between 2 and 4 months (n = 19). Group 3 had device failure between 4 and 6 months (n = 11). RESULTS: Groups 1 and 2 exhibited significantly longer device life span, that is, 77 and 82 days, respectively (P < 0.01), and group 3 exhibited device life span that was longer but not significantly so, that is, 12 days (P > 0.05), after the change from standard to Advantage TEP. Individual data indicated that the majority of participants, that is, 32 of 42 (76.2%), experienced longer device life span after changing to the Advantage prosthesis. Specifically, 9 of 12 (75.0%) users in group 1, 17 of 19 (89.5%) users in group 2, and 6 of 11 (54.5%) users in group 3 exhibited longer device life span. The combination of using an Advantage TEP, discontinuing oral antifungal agents, and reducing the number of both TEP changes and clinic visits resulted in overall cost benefits for both the user and the health care system. The cost benefit for group 1 was dollar 520.00; group 2, dollar 393.00; and group 3, dollar 204.25. CONCLUSIONS: The Advantage TEP extended device life span significantly for standard indwelling device users with documented premature device failure due to fungal colonization, reduced costs associated with tracheoesophageal voice restoration rehabilitation, and enhanced user satisfaction by eliminating use of oral antifungal agents and reducing clinic visits. SIGNIFICANCE: Use of an Advantage indwelling voice prosthesis is warranted from both cost and user satisfaction perspectives when early and repeated device failure occurs as a result of fungal colonization. EBM RATING: B-3.

Equipment Contamination↗
PubMed2003

Does the type of prosthesis influence early left ventricular mass regression after aortic valve replacement? Assessment with magnetic resonance imaging.

BACKGROUND: Debate exists regarding selection of the prosthesis type most likely to maximize early left ventricular (LV) mass regression after aortic valve replacement (AVR) for stenotic valvular disease. The aim of this study was to compare the degree of LV mass regression measured by MRI 6 months after prospectively randomized valve implantation for two biological prostheses, stented and stentless, and for two mechanical valves, tilting disc and bileaflet. METHODS: Thirty-nine consecutive patients with predominant aortic stenosis accepted for elective AVR were studied. Twenty patients requiring a tissue prosthesis were randomly assigned to receive either a Freestyle or Mosaic valve. The remaining 19 patients in whom mechanical prosthesis was indicated were randomly assigned to receive either an Ultracor or an ATS valve. RESULTS: There was no difference in valve size implanted between the compared groups. LV mass measurements were performed with MRI (1.5-T Vision, Siemens, Germany) immediately before and 6 months after surgery. All valve types produced significant postoperative reduction in LV mass compared with preoperative values (P <.01). Percent change in LV mass regression was similar between the two porcine valve types, Mosaic (24.4% +/- 11.1%) and Freestyle (21.1% +/- 16.7%), and between the two mechanical valve designs, Ultracor (19.3% +/- 9.5%) and ATS (26.3% +/- 10.8%), respectively. CONCLUSIONS: Significant LV remodeling occurs early after AVR for aortic stenosis. The degree of regression in LV mass is independent of prosthesis type implanted.

Adult↗
PubMed2004

Contact stresses and fatigue life in a knee prosthesis: comparison between in vitro measurements and computational simulations.

The evaluation of contact areas and pressures in total knee prosthesis is a key issue to prevent early failure. The first part of this study is based on the hypothesis that the patterns of contact stresses on the tibial insert of a knee prosthesis at different stages of the gait cycle could be an indicator of the wear performances of a knee prosthesis. Contact stresses were calculated for a mobile bearing knee prosthesis by means of finite element method (FEM). Contact areas and stresses were also measured through in vitro tests using Fuji Prescale film in order to support the FEM findings. The second part of this study addresses the long-term structural integrity of metal tibial components in terms of fatigue life by means of experimental tests and FEM simulations. Fatigue experimental evaluations were performed on Cr-Co alloy tibial tray, based on ISO standards. FEM models were used to calculate the stress patterns. The failure risk was estimated with a standard fatigue criterion on the basis of the results obtained from the FEM calculations. Experimental and computational results showed a positive matching.

Computer Simulation↗
PubMed1999

Fabrication and use of a surgical template for placing implants to retain an auricular prosthesis.

A procedure is described for the fabrication of a 3-dimensional surgical template to guide the placement of implants to retain an auricular prosthesis. This procedure requires a diagnostic wax pattern that is checked while on the patient to ensure it is positioned correctly and is also the correct size. The wax pattern is processed into a clear, methyl methacrylate resin, 3-dimensional surgical template. The most effective type of surgical template for planning implant placement is a 3-dimensional acrylic template that closely resembles the final prosthesis. This template will direct the implant placement where the retentive elements are most easily concealed, under the thickest areas of the prosthesis, which are the antihelix and antitragus. This location allows the best esthetic and functional results. An additional advantage of this technique is that it allows the retrieval of the diagnostic wax pattern of the auricle so that it can be used to fabricate the definitive prosthesis.

Ear, External↗
PubMed2001

Reservoir herniation as a complication of three-piece penile prosthesis insertion.

OBJECTIVES: To obtain data concerning the incidence and management of reservoir herniation in inflatable penile prosthesis surgery in a clinical investigation. Reservoir herniation after scrotal placement of inflatable penile prosthesis is an unusual complication, and a review of the published medical reports reveals only anecdotal reports and no definitive articles. METHODS: A multi-item self-addressed questionnaire was mailed to the members of the Society for the Study of Impotence questioning the occurrence of reservoir migration from the prevesical space to the inguinal canal or scrotum. In addition, the database of one of us was reviewed to determine the incidence of reservoir migration in a large series of 1206 three-piece penile prostheses. RESULTS: The response rate was 38%. A minority of respondents (28%) were familiar with the problem. Of those who had experienced this complication, the occurrence was very rare and usually appeared in the immediate postoperative period, often in association with vigorous coughing spells or vomiting. The responders also indicated that imperfect surgical technique might have been implicated in some cases. Management usually consisted of reservoir replacement or repositioning through an inguinal incision with repair of the defect. Alternatively, several surgeons used the existing scrotal incision if the patient presented in the immediate postoperative period. The incidence of reservoir herniation was 0.7%. CONCLUSIONS: Reservoir herniation is a rare complication of inflatable penile prosthesis surgery that occurs almost exclusively in penoscrotally placed prostheses. Familiarity with various approaches to the management of this complication is clinically useful to urologists performing penile prosthesis surgery.

Foreign-Body Migration↗
PubMed1989

Mandibular reconstruction with the THORP condylar prosthesis after hemimandibulectomy.

The subject of this paper is the evaluation of the advantages pertaining to the THORP (titanium hollow screw reconstruction plate) condylar prosthesis for reconstruction after hemimandibulectomy and exarticulation. The THORP condylar prosthesis is three-dimensionally adjustable, enabling the intraoperative meticulous functional adaptation of the condyle. Various designs of the condyle make it possible to achieve optimal congruency between the articular fossa and condyle. The anchorage of the prosthesis to the stump of the mandible is achieved with perforated hollow-screws rigidly fixed to the plate, thus producing optimal functional stability. The long-term follow-up of eleven cases, reconstructed with this system, confirmed the correct guidance and functional efficiency of this type of condylar prosthesis.

Adolescent↗
PubMed2001

[The Roseland prosthesis in the treatment of osteoarthritis. A five years experience with the same surgeon].

INTRODUCTION: The results of the Roseland trapeziometacarpal prosthesis in the treatment of the TMP arthritis has been reviewed and the trapezial component fixation discussed. METHOD: The material has been collected between November 1995 and January 2000. The immobilisation lasted 15 days if the prosthesis was cemented and one month if not. The following criteria were studied: pain, opposition, first and the second metacarpal angle, patient satisfaction, X-rays data, surgeon opinion on the components position, complication and re-operation. RESULTS: The series is made of 45 cases (43 patients), eight males and 37 females. The average age was 59.7 years, with an average pre-operative duration of 3.5 years. X-rays data shows 43% with Dell II and 33% with Dell III aspect. 19 prosthesis were cemented, 22 not, 9 cases had a mixed fixation. The average follow up is 14 months. There was no or few post-operative pain (74% of cases). The opposition has been improved in most of the cases. 78% of the patients were satisfied. Post-operative X-rays were correct in 66% for the trapezial component and in 86.5% with the metacarpal one. There were 12 complications, with eight trapezial component failures. Eight patients were re-operated on. All cases were satisfying then. DISCUSSION: If some foreign causes occurred in some complication, six failures were due to a technical problem. We must point out the frequency of failure with the cemented trapezium. However, the Roseland prosthesis is a satisfying arthroplasty but the trapezial component implantation must be improved.

Aged↗
PubMedDate not supplied

[Design and first clinical results with the ZMR taper revision prosthesis].

AIM: The purpose of this study was to survey and to evaluate the first clinical and radiological results with the cementless ZMR taper hip prosthesis. METHOD: The modular distal-tapered stem was designed with a roughened titanium surface and sharp splines to achieve secure distal fixation and rotational stability. 90 ZMR taper hip prostheses were implanted between October 1999 and July 2002. Out of these, 4 interventions were primary and 86 were revision procedures. In 43 cases a complete hip prosthesis revision and in 43 cases a stem revision was necessary. The mean age of the 90 patients (42 males, 48 females) was 67.1 years. The mean follow-up period was 7.6 months (3 to 25 months). RESULTS: The stem displayed an excellent distal fixation. The mean subsidence could be measured with 4.3 mm. Furthermore, most cases showed a particularly favourable remodelling of the proximal femoral bone stock. Complications associated with revision included intraoperatively 4 femur fractures, 3 femur fissures, 5 femur perforations, 2 trochanter fractures and postoperatively 19 dislocations, 5 superficial wound infections, 2 transient palsies, 1 pulmonary embolism, 1 stem rotation and 4 wound healing failures. Considering these complications 15 re-revisions were necessary and the ZMR taper hip prosthesis had to be exchanged in 3 cases. CONCLUSION: On the one hand the ZMR taper hip prosthesis proved its value, particularly with regard to the stem modularity, the excellent distal fixation in conjunction with the possibility of partial body weight bearing and the rapid bone remodelling of the femur. On the other hand an increased number of postoperative complications and re-revisions occurred. Further long-term studies seem to be essential.

Aged↗
PubMed2005

Clinical experience with the Mentor Alpha-1 inflatable penile prosthesis: report on 65 patients.

OBJECTIVE: To evaluate the complications and prosthesis survival associated with implantation of the Mentor Alpha-1 inflatable penile prosthesis (IPP) for the treatment of erectile dysfunction (ED). MATERIAL AND METHODS: Between August 1995 and March 2003, 65 patients underwent implantation of a Mentor Alpha-1 IPP at the Urological Departments of Skejby or Aalborg University Hospitals. Patient data were obtained retrospectively from medical files. RESULTS: The follow-up period ranged from 1 to 96 months (median 48.5 months). Twenty-one patients (32%) experienced complications that required revision. The majority of complications consisted of mechanical problems, but infection was also a large contributor to the complication rate. Seven patients (11%) had the prosthesis permanently removed due to infection. Kaplan-Meier estimates of the 5-year prosthesis survival rates with and without successful revisions due to complications were 88% and 63%, respectively. CONCLUSIONS: The Mentor Alpha-1 IPP is an efficient treatment for ED in situations where less invasive therapy has failed. The risk of infection or mechanical failure must not be ignored. Patients should be informed of this risk before agreeing to implantation surgery.

Erectile Dysfunction↗
PubMed2001

Mechanical reliability of the AMS 700CXM inflatable penile prosthesis for the treatment of male erectile dysfunction.

PURPOSE: The AMS 700CXM inflatable penile prosthesis with medium controlled expansion cylinders was introduced in 1990 to provide a device with controlled expansion in girth and fitness for Asian men. We reviewed our experience with the AMS 700CXM prosthesis with particular regard to postoperative complications and reliability. MATERIALS AND METHODS: From January 1991 to April 1999, 273 men with erectile dysfunction underwent primary penile prosthesis implantation with the AMS 700CXM. Functional status of the prosthesis was assessed retrospectively by reviewing the medical records and a telephone interview. RESULTS: Patient age was 24 to 78 years and mean followup was 49 months. Of the 28 complications (10.3%) 8 (3%) were nonmechanical and 20 (7.3%) were mechanical. Nonmechanical complications included infection in 2 cases, erosion in 3, surgical complications in 2 and tube kinking in 1. Mechanical complications involved a cylinder tear in 11 cases (4%), pump failure in 4 (1.5%) and a reservoir tear in 2 (0.7%). Mechanical reliability of the device was 98.2% after 2, 95.7% after 3 and 90.4% after 5 years. CONCLUSIONS: The AMS 700CXM is suitable for Asian men and its mechanical reliability is excellent. However, more device modifications are needed to guarantee good reliability during long-term followup.

Adult↗
PubMed2005

Shape-memory stapes prosthesis for otosclerosis surgery.

OBJECTIVES: The aim of this study was to determine the efficacy of a shape-memory alloy, Nitinol, as a component of an improved stapes prosthesis. STUDY DESIGN: Prospective laboratory and clinical study to develop a Nitinol stapes prosthesis. METHODS: Various diameters of Nitinol wire and temperature transition variants were analyzed with regard to ease of deformation, response to heating, and strength. The size and geometry of the closed hook was determined by measurement of 50 incus cadaver bones. Several heat sources for activating the shape memory were evaluated, including electrocautery, lasers, and warm water. Trial surgeries were then performed on human temporal bones in the laboratory. The closure characteristics of the Nitinol loop were studied. Magnetic resonance imaging (MRI) testing at 1.5 Tesla was performed to determine safety during MRI studies. Preliminary human subject trials were then instituted. RESULTS: In all cases, a low heat condition was ample to activate the shape memory characteristics of the hook and return it to a closed position after it had been opened. Laser power was generally set well below the power needed for removing bone. The Nitinol loop closed snugly around the incus with application to the top of the hook with a low temperature laser setting. Almost any heat source was effective. MRI testing at 1.5 Tesla showed no movement of the prosthesis. Preliminary results in human subjects showed excellent air-bone closure. The Nitinol loop holds uniform contact around the incus. CONCLUSIONS: The Nitinol piston greatly simplifies the stapedectomy procedure by taking the need for a hand operated instrument out of the surgeon's hands. Because of the nature of the Nitinol wire, it can never over-crimp. All these characteristics make the prosthesis advantageous for otosclerosis surgery.

Alloys↗
PubMed1996

Controlled retainer-screw access placement for screw-retained implant prosthesis.

An implant-supported prosthesis is often secured to the underlying gold cylinders by retaining screws. There must be access to these screws from the oral surface of the prosthesis. Conventional preparation of this access is from the oral surface. This approach is difficult because the underlying gold cylinder is obscured. It may be damaged by a rotary cutting instrument as the access is prepared above it, because the cylinder cannot be seen during the preparation. Alternatively, the access hole may be unnecessarily enlarged in an attempt to find the cylinder. This loss of structure may weaken the prosthesis. A new approach, using 18-gauge stainless steel wire as a rotary cutting instrument, permits preparation of the access chamber from the intaglio surface of the prosthesis. This reduces risk of damage to the gold cylinder and is less destructive to the overlying material.

Bone Screws↗
PubMed2003

Contemporary aspects of penile prosthesis implantation.

PURPOSE: Erectile dysfunction today has a number of effective treatment options. This review was undertaken to examine the contemporary role of penile prosthesis implantation in the treatment of this disorder. MATERIALS AND METHODS: A MEDLINE search was performed on the topic of penile prostheses and implants. Current literature was reviewed with regard to types of penile implants, issues related to prosthesis implantation, results, and patient/partner satisfaction. RESULTS: Mechanical failure rates for early penile prostheses, especially the inflatable type, were unacceptably high. Advances in both prosthesis design and implantation techniques have resulted in increased device survival with 5-year actuarial survival rates free of mechanical failure ranging from 86.2 to 93.6%. Recent reviews of implant recipients show 83 and 85% satisfaction and for partners 70 and 76% satisfaction. CONCLUSIONS: When systemic therapy for erectile dysfunction fails, men have a variety of other options to choose from. Penile prosthesis implantation is an option that is feasible for nearly every man with this disorder. Current device survival rates and patient and partner satisfaction rates are high.

Adult↗
PubMed2005

Impact of prosthesis-patient size on functional recovery after aortic valve replacement.

BACKGROUND: Prosthesis-patient size mismatch results when an implanted prosthetic aortic valve is of insufficient size for a patient's body surface area. The relation between prosthesis-patient size and functional capacity and adverse postoperative outcome is inconsistent. Our objectives were to examine the impact of valve replacement, continuous prosthesis-patient size, and other factors on functional recovery after aortic valve replacement (AVR) with the Duke Activity Status Index (DASI). METHODS AND RESULTS: From June 15, 1995, through May 14, 1998, 1108 patients underwent AVR after completing a DASI survey. Of these, 1014 completed a postoperative DASI survey at an average of 8.3 months postoperatively. Logistic ordinal regression was used to examine the influence of demographic variables, comorbidities, baseline DASI scores, indexed valve orifice area, standardized orifice size, and postoperative morbid events on postoperative DASI. There was overall improvement in postoperative functional recovery reflected by median preoperative and postoperative DASI scores of 29 and 46, P<0.001, respectively. Neither indexed orifice area, P=0.94, nor standardized orifice size, P=0.96, was associated with functional recovery. Female sex, increasing age, elevated serum creatinine, increased central venous pressure, and red blood cell transfusion were factors associated with poor postoperative functional recovery. CONCLUSIONS: A majority of patients report improvement in functional quality of life early after AVR. Similar functional recovery was demonstrated for patients along the full spectrum of valve sizes indexed to body size, even for values considered to represent severe mismatch for patient size. Factors other than prosthesis-patient size influence functional quality of life early after AVR.

Adult↗
PubMed1995

An estimation of fatigue life for a carbon fibre/poly ether ether ketone hip joint prosthesis.

A fracture mechanics approach was applied to estimate the life of a prosthesis injection moulded from short carbon fibre reinforced poly ether ether ketone. Flexural modulus and strength, fracture toughness, fatigue endurance limit, fatigue crack growth rate and threshold stress intensity factor were determined. The dimensions of the test pieces were selected to yield fibre orientation and fibre length distributions similar to those obtained in the prosthesis. Stress levels generated in the prosthesis under different activities were estimated by conducting three-dimensional finite element analysis. It was shown by a fracture mechanics approach that a fatigue failure due to the propagation of an embedded elliptical slit, under these stresses, would be unlikely for a crack length smaller than 1.85 mm. However, the cement would fail under the same conditions, irrespective of the type of the prosthesis employed.

Benzophenones↗