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At least 433 records · Page 24Linked to original sources
PubMed2006

[Variable length titanium prostheses for type III tympanoplasty. Intraoperative length adjustment and fixation of the cartilage overlay].

INTRODUCTION: For type III tympanoplasty by partial ossicular replacement prosthesis (PORP) or total ossicular replacement prosthesis (TORP), the length of the prosthesis must match the individual intraoperative anatomical and physiological characteristics. MATERIALS AND METHODS: Databanks were used to determine the necessary sizer length of the sizer disc. The measurement template for the size of the cartilage to overlay the prosthesis headplate was derived from the headplates of the Tübinger titanium prostheses (TTP) and the Dresdener titanium prostheses. Finally all functions were integrated into a synthetic plate. RESULTS: The result was a simple and reasonably priced disposable multifunctional instrument (Tübinger sizer disc TSD) which allowed an exact measurement for every prosthesis in TORP and PORP. For the TTP-Variac, the TSD enabled the simple intraoperative production of prostheses with the length desired by the surgeon. For PORP the TSD enabled an adaptation of the diameter of the prosthesis foot for TTP, TTP-Vario and TTP-Variac and provided a template for the size determination of the cartilage overlay of the titanium prosthesis head. The sizers and the resulting prostheses were used for initial tympanoplastic operations. Audiometric investigations carried out 6 weeks postoperatively gave results corresponding to those previously obtained in a study with TTP and TTP-Vario using the old instrumentation. CONCLUSIONS: The new instrumentation leads to an improvement of the intraoperative practicability and a simplification. The audiological results remain the same.

Disposable Equipment↗
PubMed2003

[Myoelectric prostheses for kindergarten age children. Analysis of first reactions and experiences].

During the last few decades myoelectric prostheses were generally provided for adolescent or adult patients. Since 1991 the availability of smaller sized electric hands in conjunction with technical improvements enabled the introduction of myoelectric prostheses for preschool children.However, this progress remained widely unnoticed in Germany. This study presents the authors' experiences with prosthetic devices for preschool children with unilateral upper limb deficiency (congenital and traumatic). Twenty children received a myoelectric prosthesis between the ages of 2 and 5 years (3.9+/-1.1 years). The follow-up period was 1.7 years. The prosthesis was worn for an average of 5.6 h/day. Our hospital-based intensive training program positively influenced the acceptance rate. All children with a below-hand amputation rejected their prosthesis.However, the general dropout rate in preschool children is conspicuously lower compared to adults. In this study 2.4+/-2.9 repairs per year per patient were required. The susceptibility for repairs in this age group is much higher for myoelectric prostheses compare to body-powered devices. Since the correct indication and the intensive training program significantly influence the acceptance rate, the introduction of myoelectric prostheses to preschool children should take place at specialized centers with an interdisciplinary team composed of orthopedists,occupational therapists,and technicians.

Arm↗
PubMed2004

Clinical and functional comparison of uni- and bicondylar sledge prostheses.

The aim of the present study was the evaluation of differences in clinical results, proprioceptive performance and gait in patients with unicondylar and bicondylar sledge prostheses of the knee. In a retrospective study, 17 patients with unicondylar sledge prostheses were compared with 15 patients with bicondylar sledge prostheses. Clinical examination was rated using HSS, Knee Society, and patellar scores and a visual analogue scale for pain. Proprioceptive performance was examined using sway measurements during single leg stance on a force platform. In addition, the patients underwent 3-D gait analysis including measurements of ground reaction forces and surface electromyographic (EMG) investigation of the lower extremity. Comparing both patient groups in clinical scores, gait, EMG and proprioception, no significant differences were found. Implantation of bicondylar sledge prostheses retaining both cruciate ligaments achieves functional results as good as unicompartmental arthroplasty. The presented results might encourage future research on new models of total joint replacement with preservation of both cruciate ligaments.

Aged↗
PubMed2003

Augmentation mammaplasty of teardrop-shaped breasts using round prostheses.

A new submuscular-subglandular technique to correct teardrop-shaped breasts using round prostheses is presented. In this technique the prostheses are only partially covered by muscle. The muscle is also divided to enhance the projection at the nipple level without the need for anatomical prostheses. A series of 911 implanted prostheses is presented and the results are discussed with regard to both visual and tactile aspects, as well as the dynamic appearance. The complication rates are surprisingly comparable to those of totally submuscular implant techniques. This perhaps suggests that the coverage provided by the divided muscle is sufficient to minimize the contact between the implant and the gland, often considered the primary cause of the higher capsular contracture rates found in techniques using subglandular locations.

Adult↗
PubMed2002

[Is chronic graft rejection the reason for degenerative changes in allogeneic and xenogeneic heart valve prostheses: immunohistochemical evaluation of inflammatory factors].

OBJECTIVES: After a period of 5 to 10 years, biological heart valve prostheses undergo degenerative processes, which finally lead to dysfunction and complete destruction. Although many efforts have been made to identify underlying mechanisms, many questions remain unanswered. Here we evaluate immunological factors and their potential role in biological heart valve destruction. PATIENTS AND METHODS: Allogeneic (n=10) and xenogeneic (n=3) aortic valvular prostheses, as well as aortic valves retrieved from transplanted human hearts, which had to be replaced because of chronic graft rejection (n=4) were analyzed. Aortic valves from human donor hearts (native) (n=4), which were considered not transplantable served as controls. Endothelial expression patterns of the following adhesion molecules were analyzed by immunohistochemistry: selectin family: ELAM-1, CD62, integrin family: VLA-1, -2, -3, -4, -5, and -6, immunoglobulin supergene family: PECAM-1, ICAM-1, and -2, and class I heavy chain proteins, complementary adhesion molecules: CD34, CD44 and the von Willebrand factor. RESULTS: ELAM-1, ICAM-1 and -2, CD34, CD44 and class I heavy chain proteins, all molecules which play significant roles during inflammatory processes, showed stronger expression patterns in allogeneic and xenogeneic aortic heart valve prostheses compared to native or chronically rejected valves. Furthermore, the von Willebrand factor stained positive only on allogeneic and xenogeneic valves. Only mild differences were observed regarding the expression of integrin molecules and CD62. CONCLUSIONS: Immunological reactions play a major role in the degeneration of biological heart valve prostheses. This is underlined by observations made on aortic valves from chronically rejected cardiac grafts, which did not show any degenerative alterations. Thus, since immunosuppressive therapy after heart valve replacement is no reasonable alternative, novel and future approaches in "tissue engineering" will hopefully help avoid tissue degeneration, while preserving the advantage of biological tissue origin.

Animals↗
PubMed1997

[Gasless video-endoscopic implantation of aortobifemoral vascular prostheses via extraperitoneal approach in the animal experiment].

The gasless videoendoscopic implantation of GELSOFT aortobifemoral vascular prostheses times 6 x 6 mm in diameter using an extraperitoneal approach was tested in ten porcine experimental models at the Surgical Department of the University of Cologne, Germany. Gasless videoendoscopic surgery is performed with a laparolift-laparofan system. Aortobifemoral GELSOFT prostheses were successfully implanted in nine of ten animals, whereby one animal died during preparations for surgery of massive coronary infarctions. Average surgical durations using the extraperitoneal approach were 270 min. Dissection of the infrarenal aorta until occlusion took 45 min, average aortic occlusion 75 min, and iliacofemoral occlusion 45 min for the left side and 75 min for the right side. After successful videoendoscopic implantation of aortobifemoral GELSOFT prostheses all nine animals underwent laparotomy and resection of the aortobifemoral prosthetic segment. The quality of the endoscopically sutured aortic end-to-side anastomoses was examined in vitro under artificial circulation of glycerol/Ringer's lactate solution for evaluation of possible leakage and bursting pressures and then compared to conventionally sutured end-to-side anastomoses of 6-h-old porcine abdominal aorta and GELSOFT prostheses 6 mm in diameter. The maximum bursting pressure of all endoscopically sutured anastomoses was 480 mmHg mean pressure: the minimum was 140 mmHg mean pressure. The minimum leakage per minute was less than 10 ml/min for systolic pressure values between 120 and 350 mmHg. All endoscopically sutured aortic end-to-side anastomoses were comparable to conventionally sutured anastomoses concerning in vitro evaluation of bursting pressure and leakage per minute.

Anastomosis, Surgical↗
PubMed1995

Evaluation of the hemodynamic performance of small CarboMedics aortic prostheses using dobutamine-stress Doppler echocardiography.

BACKGROUND: The well-known correlation between prosthetic valve orifice area and transvalvular gradients has raised concerns about the presence of significant residual gradients when the size of the prosthesis that can be implanted is limited by the presence of a small aortic annulus. METHODS: Dobutamine-stress Doppler echocardiography was used to evaluate the hemodynamic performance of small CarboMedics aortic prostheses (19 mm and 21 mm) in 18 patients (16 women; mean age, 64 years) who had undergone aortic valve replacement 23.5 +/- 19 months (standard deviation) previously. Dobutamine infusion was started at a rate of 5 micrograms.kg-1.min-2 and increased to 10 and 20 micrograms.kg-1.min-2 at 15-minute intervals. Pulsed and continuous wave Doppler studies were performed at rest and at the end of each stage. Effective orifice area, performance index, and discharge coefficient of both valves were calculated, and peak and mean velocity and pressure drop across the prostheses were measured. RESULTS: Heart rate and cardiac output increased by 74% and 94%, respectively, and mean arterial blood pressure decreased by 9% at maximum stress. Effective orifice area, discharge coefficient, and performance index were comparable in both valve sizes at rest and maximum stress. Also, there was no significant difference in mean transvalvular pressure drop (gradient) for 19-mm and 21-mm prostheses at rest (8.1 +/- 8.4 and 4.8 +/- 3.8 mm Hg) or maximum stress (15.1 +/- 14.2 and 8.8 +/- 5.8 mm Hg, respectively). No significant correlation could be demonstrated between transvalvular pressure drop and patient's body surface area. CONCLUSIONS: These data show that 19-mm and 21-mm CarboMedics aortic prostheses exhibit equally favorable hemodynamic performance with minimal pressure gradient, both at rest and under stress conditions.

Aged↗
PubMed1985

Stubby prostheses: an alternative to conventional prosthetic devices.

Stubby prostheses offer potential advantages over conventional prosthetic devices in terms of safety, stability, and energy efficiency. Although cosmesis is compromised in the process, these short nonarticulated pylon prostheses may be a viable option to consider in bilateral A-K or knee disarticulation amputee patients under the following circumstances: (1) as a training tool to determine whether progression to full-length articulated devices is feasible; (2) as permanent prostheses for the patient whose primary need for ambulation is within his own home; (3) for the elderly bilateral amputee in whom ambulation is feasible but safety and energy efficiency are of particular importance; and (4) as a definitive device in the patient who expresses a preference for them. Two patients who have become successful users of stubby prostheses are presented to illustrate these points.

Adult↗
PubMed1989

Comparison of weight reduction in different designs of solid and hollow obturator prostheses.

Seven types of the partially edentulous maxillectomy arches based on Aramany's classification were designed to evaluate the weight reduction of hollow obturator prostheses. Six obturator prostheses were made for each type of maxillary defect, three of the solid type and three of the hollow type. The weight of each of the 42 obturator prostheses was measured and all of the data were collected and statistically analyzed. The results showed that the hollow obturator prostheses had significantly increased weight reduction, from 6.55% to 33.06% depending on the size of the defect.

Maxilla↗
PubMed1992

A socioeconomic comparison of patients receiving prostheses in a two-tier delivery system.

It has been theorized that the legalization of providers of denture care other than dentists would make dentures more affordable to and therefore more often obtained by individuals of lower socioeconomic status. The delivery of dental prostheses by nondentists (denturists) has been legalized in Arizona, Colorado, Idaho, Maine, Montana, and Oregon. This study compares the socioeconomic and utilization patterns of two groups of patients receiving prostheses: (1) those whose prosthetic services were provided by dentists and (2) those whose services were provided by denturists. The sample included 135 participants; 31 individuals with 54 prostheses made by denturists and 104 individuals with 165 prostheses made by dentists. Application of the chi-square test and the Hollingshead Two-Factor Index of Social Position revealed no statistically significant correlation, (p less than 0.05) between the provider-based groups and standard socioeconomic variables. The history and pattern of choice of provider as well as level of satisfaction were also remarkable for the similarity displayed by the two groups. It would appear that the two groups are actually one homogeneous group served by two levels of providers.

Aged↗
PubMed1994

Removable partial prostheses for the elderly.

Elderly partially edentulous patients can have teeth replaced with removable or fixed prostheses supported by mucosa, teeth, or implants. Age per se does not influence which option is best. Instead, the relative health of the patient, dental tissues, and the patient's finances determine treatment. A three-level index of these factors, the PTF index, is proposed to assist in the decision-making for treatment. Removable partial prostheses (RPPs) can be indicated for all patients because RPPs offer esthetic, versatile, noninvasive, and reversible features. They are particularly indicated when remaining teeth are questionable. If teeth are lost, they can be more easily added to existing RPPs compared with fixed prostheses. Six changes to ideal designs are illustrated in this article for prostheses with a compromised dentition, to make continued prosthetic service simpler.

Aged↗
PubMed1983

Quantitative SEM-analysis of adhesive and thrombogenic properties of vascular prostheses.

The perfusion technique to measure the relative adhesive and thrombogenic indices of vascular prostheses by a quantitative scanning electron microscopy has been described. To normalize the experiments with different samples of plasma we compared the adhesive and thrombogenic properties of the analyzed prostheses with those of normal and denuded human umbilical vein. The results indicate that adhesive and thrombogenic indices of Dardik, Bakulev and Gore-Tex grafts approximate to those of the non-damaged umbilical vein, while the same indices of Solcograft-P prostheses are considerably higher. The method may be useful for standardizing the properties of new prostheses and bioimplants for cardiovascular surgery.

Bioprosthesis↗
PubMed1990

Rapid endothelialization of microporous vascular prostheses covered with meshed vascular tissue: a preliminary report.

The aim of our study was to induce rapid endothelialization of vascular prostheses which replace malfunctioning blood vessels. We developed a technique of meshing a section of autologous arterial or venous tissue, wrapping it around a porous vascular prosthesis and fixing it with a running suture. This combination was used to replace a 1 cm segment of rat abdominal aorta. The implanted specimens were harvested after 8, 16, 24 or 135 d and evaluated for cellular ingrowth and endothelial coverage with light and scanning electron microscopy. All grafts were patent when harvested. Cells of the meshed tissue were observed to migrate through the pores in the prosthetic wall to cover the luminal surface. The presence of meshed vascular tissue around the prosthesis resulted in complete endothelialization within 24 d and sometimes within 8 d after implantation. This endothelial layer is still present after 135 d. In control prostheses without meshed vascular tissue, complete endothelialization takes at least 42 d. We conclude that the application of meshed vascular tissue around porous vascular prostheses results in patent prostheses with a rapidly formed and long-term surviving endothelium layer.

Animals↗
PubMed2005

Feasibility and diagnostic accuracy of quantitative assessment of mechanical prostheses leaflet motion by transthoracic and transesophageal echocardiography in suspected prosthetic valve dysfunction.

Transthoracic (TTE) and transesophageal echocardiography (TEE) are the standard techniques for the evaluation of prosthetic valve function. However, quantitative evaluation of leaflet(s) motion is not routinally carried out, although leaflet(s) opening and closing angle measurements are important information to recognize prosthetic dysfunction. For this purpose, cinefluoroscopy is considered the "gold standard" technique. The aim of this study was the evaluate the diagnostic accuracy of TTE and TEE in the quantitative assessment of leaflet motion in patients with mechanical protheses. One hundred-eleven patients with mitral (single disk 18; bileaflet 48) and aortic (single disk 22; bileaflet 23) prostheses, were referred to TTE, TEE, and cinefluoroscopy for electrical cardioversion of atrial fibrillation (n = 40) or suspected prosthesis dysfunction (n = 71). Echocardiographic evaluation included leaflet(s) opening and closing angle measurements; results were compared with cinefluoroscopy. For mitral prostheses, opening and closing angles were correctly identified by TTE in 85% and by TEE in 100% of patients, regardless of prosthetic valve type, with a good concordance with cinefluoroscopy. For aortic prostheses, opening angles were correctly identified by TTE and TEE, respectively, in 40% and 77% of patients with single-disk and in 13% and 35% of patients with bileaflet prostheses. Both TTE and TEE were rarely able to identify closing angles. In conclusion, quantitative evaluation of mitral leaflet(s) motion may be accurately achieved with TTE and TEE, leading to increased diagnostic efficacy of prosthetic valve dysfunction. In the aortic position, TTE and TEE allow a quantitative evaluation of leaflet(s) dynamics only in a minority of patients and cinefluoroscopy still remains the first-choice technique.

Aortic Valve↗
PubMed2005

Fitting a bilateral transhumeral amputee with utensil prostheses and their functional assessment 10 years later: a case report.

Traumatic transhumeral amputations resulting from electric burn injury are uncommon and present a significant rehabilitation challenge. Compensating for loss of fine, coordinated function of the upper extremities with prostheses is difficult medically, technologically, psychologically, and socially. We followed up a patient with traumatic bilateral transhumeral amputation who was fitted with specially designed bilateral low-temperature utensil prostheses for 10 years. A bilateral utensil prosthesis consists of 2 thermoplastic sockets, an elastic harness, 2 utensil holders, and several different utensils. The characteristics of utensil prostheses are low cost, quick fabrication, and responsiveness to a patient's needs. Ten years after the patient's first prosthesis fitting, he still used these specially designed prostheses. By using these devices and his feet, the patient has regained independence in most activities of daily living and gained a new working skill.

Activities of Daily Living↗
PubMed2005

Load-shift--numerical evaluation of a new design philosophy for uncemented hip prostheses.

All hip replacement prostheses alter the load transfer from the hip joint into the femur by changing the mechanical loading of the proximal femur from an externally to an internally loaded system. This alteration of the load transfer causes stress shielding and might lead to severe bone loss, especially with uncemented prostheses. To minimize these effects, load transfer to the femur should occur as proximal as possible. In order to support sufficient primary stability, however, directly post operative (PO) distal stabilization is reasonable. Consequently, the prostheses have to alter its mechanical characteristics after implantation. This concept is referred to as load-shift concept. Primary stability during the early PO state is provided by a prosthesis shaft, which is widened at the tip by a biodegradable pin. After resorption of the pin load transfer occurs no longer distally. The objective of this study was the numerical evaluation of the load-shift concept. The analysis was performed with a finite element model. Three-dimensional non-linear dynamic gait analyses data were used to evaluate whether the load transfer during walking can be altered effectively by insertion and resorption of a distal pin. Directly PO 38% of the transverse load is transferred through the prosthesis shaft and micromotion of the proximal prostheses tip is below 55 microm. After resorption of the pin, no transverse loads are transferred through the prosthesis shaft. Therefore, the loading of the proximal bone tissue is far more pronounced than in the case of a standard prosthesis, demonstrating the feasibility of the load-shift concept. A balanced degradation of the pin simultaneously with the ingrowth of the prosthesis is expected to reduce hip replacement complications.

Absorbable Implants↗
PubMed2006

Biofilm formation on clinically noninfected penile prostheses.

PURPOSE: Biofilms are matrix enclosed bacterial populations that adhere to each other and/or to surfaces of implanted medical devices. Biofilm formation has consistently been demonstrated in association with infected penile prosthetic material. Clinically noninfected patients undergoing revision for mechanical malfunction have a surprisingly high rate of positive intraoperative cultures. After revision replacement prostheses have a higher rate of postoperative infection than first time implants. We characterized biofilm formation on penile prostheses in clinically noninfected patients undergoing revision surgery. MATERIALS AND METHODS: Ten patients undergoing revision or removal of inflatable penile prosthetic devices due to mechanical malfunction were included. Specimens from the corporeal cylinders, scrotal pump and reservoir were analyzed. Bacterial biofilm coverage was detected and characterized using confocal scanning laser microscopy. RESULTS: Bacterial biofilm formation associated with multiple microorganisms was demonstrated on 8 of 10 prostheses. Biofilms consisted of gram-positive rods, cocci and fungal elements. CONCLUSIONS: The degree of biofilm formation on these prosthetic devices suggests that most patients have bacterial coverage on the implant. Host mechanisms to control infection may lead to a homeostatic balance that enables biofilms to exist on the surface of the prosthesis without generating clinical infection. A critical threshold of biofilm extent may exist beyond which clinical infection may occur. These results justify further evaluation of biofilms and penile prosthesis infections. Furthermore, the findings help to explain why strategies such as mini salvage procedures to eliminate subclinical biofilms may decrease the postoperative infection risk in patients undergoing repair or replacement of penile prostheses.

Biofilms↗
PubMed2006

Assessment of radionuclide arthrography in the evaluation of loosening of knee prostheses.

BACKGROUND: Radionuclide arthrography (RNA) is an established technique in the evaluation of hip prostheses but there is scant literature on its role in knee prostheses and no data specifically related to unicompartmental knee prostheses. We reviewed our experience with radionuclide arthrography in total (TKRs) and unicompartmental (UKRs) knee arthroplasties. METHODS: A retrospective review of 66 consecutive RNA studies that either had direct surgical correlation or arthroscopic assessment in conjunction with at least 12 months of clinical and radiological follow-up. These formed the basis of our case note review. 26 studies had a confirmed diagnosis of prosthetic loosening. RESULTS: By using standardised criteria for diagnosis and an early and late imaging protocol at 30 min and 4 h, RNA had an overall sensitivity of 88% and a specificity of 88% for the diagnosis of prosthetic loosening. The individual sensitivities and specificities were 93% and 86% for TKRs and 82% and 92% for UKRs. The technique was unable to detect femoral component loosening unless a long femoral stem was present, although only 8% of episodes of prosthetic loosening did not involve the tibial component. CONCLUSION: Radionuclide arthrography should be considered as a useful diagnostic test for the evaluation of loosening of the tibial component of knee prostheses but requires early and late imaging and close attention to detail to achieve optimal results.

Aged↗