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PubMed2005

Rehabilitation with dental prosthesis can increase cerebral regional blood volume.

Treatment with denture for edentulous people is highly important for maintaining quality of life. However, its effect on the brain is unknown. In this experimental study, we hypothesized that dental prosthesis can recover not only the physical condition of mastication system but also the regional brain activity. We evaluated functional brain imaging of edentulous subjects fixed by dental implant prosthesis with clenching tasks by multi-channel near-infrared optical topography. Results revealed a significantly (P<0.001; paired t-test) increased cerebral regional blood volume during maximum voluntary clenching task by implant-retained prosthesis. There were no statistically significant differences between patients with and without prosthesis in the latency to the maximum regional blood volume after the task. Conclusively, clenching can be effective for increasing cerebral blood volume; accordingly maintenance of normal chewing might prevent the brain from degenerating.

Bite Force↗
PubMed2004

The hydrophilic-coated inflatable penile prosthesis: 1-year experience.

INTRODUCTION: Penile prosthesis infections are a devastating complication for both patient and surgeon. Efforts to reduce the risk of infection from these elective procedures are a major focus of research and development by the major prosthesis companies. The Titan inflatable penile prosthesis (Mentor Corporation, Santa Barbara, CA) is coated with polyvinylpyrrolidone (PVP), a hydrophilic substance that reduces bacterial adherence and absorbs and elutes the antibiotics the device is immersed in intraoperatively. The Titan device was introduced to the American market in September 2002. This study reports the 1-year experience in the U.S. with the Titan and compares infection rates with the noncoated Alpha-1 IPP made by Mentor. MATERIALS AND METHODS: Two thousand three hundred and fifty-seven Titan prostheses were implanted in the U.S. from September 2002 to August 2003, compared with the 482 noncoated Alpha-1 IPPs implanted over the same time period. Infection rates were compared, along with bacterial culture data. All data were collected from Mentor's internal database, as generated from the FDA's mandatory reporting of explanted medical devices, and available on the internet. RESULTS: The infection rate for the coated Titan IPP was 1.06% (25/2,357). During the same time period, the infection rate for the Alpha-1 noncoated prosthesis was 2.07% (10/482). Staphylococcus species predominated in both groups (9/25 Titan, 6/10 Alpha-1). CONCLUSIONS: At 1 year of follow-up, the data demonstrate that the hydrophilic coating on the Titan IPP confers a significant advantage in reducing the rate of infection over the noncoated device. Long-term follow-up on this first year database is needed before this innovation is accepted as the standard of care for prosthetic surgery. Nevertheless, the theoretical reduction in bacterial adhesion conferred by the hydrophilic PVP surface and the ability to choose which antibiotic the device is immersed in intraoperatively gives the implanting surgeon distinct advantages with this new product.

Anti-Bacterial Agents↗
PubMed2006

Validation of a voice prosthesis questionnaire to assess valved speech and its related issues in patients following total laryngectomy.

OBJECTIVES: To establish the reliability and validity of a new self-administered questionnaire to assess valved speech and its related issues in patients who have undergone a total laryngectomy operation. DESIGN: Cross-sectional psychometric validation study. SETTING: Tertiary cancer care centre. PATIENTS: We identified sixty-one total laryngectomy patients with no sign of recurrent disease and using voice prosthesis from the speech and language therapy database of the Royal Marsden Hospital. The patients were assessed using a postal self-administered voice prosthesis questionnaire concerning the voice valve and it's related issues. Patients were also asked to complete the University of Michigan voice related quality of life and University of Washington head and neck quality of life (version 4) questionnaires. MAIN OUTCOME MEASURES: Test-retest and internal consistency reliability; content; criterion and construct validity. RESULTS: We received completed questionnaires from fifty-one of the sixty-one total laryngectomy patients identified for the study providing a response rate of 84%. The median age of the group was 65 years (range: 40-85) with thirty-seven males and fourteen females. The internal consistency reliability using the Cronbach's alpha coefficient was 0.87 (range: 0.85 to 0.89). Test-retest reliability showed that more than 75% of patients had a score on re-test that was within 1 point of their original score. Content validity was ensured during the design process. The median Spearman correlation coefficient was 0.25 for convergent construct validity with the University of Washington head and neck quality of life questionnaire and 0.64 for criterion validity on comparison with the University of Michigan voice related quality of life scale. CONCLUSIONS: The voice prosthesis questionnaire is the first validated and reliable self-administered questionnaire designed specifically for evaluating valved speech and its related issues in patients who have undergone total laryngectomy. The voice prosthesis questionnaire has significant utility for audit, outcomes research and monitoring in this unique group of patients.

Adult↗
PubMed2006

Tilt determination in MEMS inertial vestibular prosthesis.

BACKGROUND: There is a clear need for a prosthesis that improves postural stability in the balance impaired. Such a device would be used as a temporary aid during recovery from ablative inner-ear surgery, a postural monitor during rehabilitation (for example, hip surgery), and as a permanent prosthesis for those elderly prone to falls. METHOD OF APPROACH: Recently developed, small instruments have enabled wearable prostheses to augment or replace vestibular functions. The current prosthesis communicates by vibrators mounted on the subject's trunk. In this paper we emphasize the unique algorithms that enable tilt indication with modestly performing micromachined gyroscopes and accelerometers. RESULTS: For large angles and multiple axes, gyro drift and unwanted lateral accelerations are successfully rejected. In single-axis tests, the most dramatic results were obtained in standard operating tests where balance-impaired subjects were deprived of vision and proprioceptive inputs. Balance-impaired subjects who fell (into safety restraints) when not aided were able to stand with the prosthesis. Initial multiaxis tests with healthy subjects have shown that sway is reduced in both forward-back and sideward directions. CONCLUSIONS: Positive results in initial testing and a sound theoretical basis for the hardware warrant continued development and testing, which is being conducted at three sites.

Acceleration↗
PubMed2005

Ring-reinforced prosthesis for paracolostomy hernia.

BACKGROUND: The reported recurrence rate after paracolostomy hernia repair, with or without mesh, varies between 47 and 100%. We developed a polypropylene mesh prosthesis with a central opening, reinforced with a polypropylene ring, that can be implanted suprafascially through a mucocutaneous incision. METHODS: The results of a consecutive series of 46 patients with paracolostomy hernia, who were implanted with this prosthesis between October 1988 and November 2000 in 12 hospitals, were analyzed. The mean follow-up was 5 (range 1-13) years. RESULTS: The early infection rate was 4.3%. Two patients were lost to follow-up. The late infection rate was 2.3%. Seven patients (15.9%) developed a recurrent parastomal hernia and were all reoperated. The prosthesis was definitively removed in 10 patients. CONCLUSION: Although implantation of this new prosthesis is not without complications, it offers the lowest reported recurrence rate until now.

Aged↗
PubMed1977

The pathology of wear in the Beall model 104 heart valve prosthesis.

We examined 13 Beall model 104 prostheses recovered at surgery or autopsy 10 to 84 1/2 months after insertion and observed the pattern of prosthesis wear. We defined wear as "mild" when the disc was notched but neither the metal of the struts was exposed not the cloth seat torn. In "moderate" wear the disc was notched, the Teflon coating of the struts was worn away exposing the underlying metal but the cloth of the set was not torn. The cloth seat was torn in "severe" wear, exposing the metal seat and causing a different pattern of disc erosion. In one case this allowed the disc to tilt into the valve lumen and, later, to escape from its cage. Most of the prostheses studied showed "moderate" or "severe" wear. We believe that some degree of wear is inevitable. Clinical signs and symptoms were not specific but a rough correlation existed between the severity of hemolysis, as indicated by serum LDH levels, and the degree of prosthesis wear. When wear was "severe", the results of cardiac catheterization studies usually mirrored the change, but there were a few exceptions. All patients with the Beall model 104 prosthesis may eventually develop "severe" wear, and we recommend regular reassessment with a view toward prosthesis replacement.

Adult↗
PubMed2002

A new vascular polyester prosthesis impregnated with cross-linked dextran.

It is essential that a synthetic vascular graft is preclotting prior to implantation in order to prevent blood leaking through the graft wall. We have impregnated a knitted polyester prosthesis with cross-linked dextran. The aim of this study was to develop a process for obtaining an impervious prosthesis and to compare the characteristics of this dextran-impregnated graft with those of a commercially available collagen-impregnated graft. This new vascular prosthesis was coated with dextran; sodium trimetaphosphate was utilized as the cross-linking agent. In an attempt to determine the optimal conditions for impregnation, the dynamic viscosity of the dextran solution was measured during the cross-linking reaction. The results suggest that the dynamic viscosity is correlated with the concentrations of dextran, sodium hydroxide, and sodium trimetaphosphate. The effect of temperature on the dynamic viscosity was also investigated. The water permeability, the coating weight, and the structure of the dextran-impregnated graft were compared with those of a collagen-impregnated prosthesis. The water permeability of the vascular grafts was reduced by dextran impregnation, from 1010 ml/min per cm2 for the control to 0.04 ml/min per cm2 under standard testing conditions. The dextran coating is capable of rendering the graft impervious to water. The coating weight of the graft treated with dextran was approximately the same as the weight of the collagen-impregnated graft. Finally, the morphology of the prosthetic wall was analyzed using scanning electron microscopy. The promotion of endothelial cell recovery was only observed for the polyester grafts treated with dextran or collagen.

Blood Vessel Prosthesis↗
PubMed1988

Experimental evaluation of the mitroflow pericardial heart valve prosthesis. Part II. Pathologic examination.

The results of the morphologic and histopathologic examination of 37 bovine pericardial heart valve prostheses that were retrieved after experimental implantation in Chacma baboons for periods of one to twelve months are presented in this study. The implanted prostheses consisted of 33 Mitroflow valves, size 21 mm, that belonged to four different groups according to the method of preparation of the pericardium (process I to IV) and 4 commercially available Ionescu-Shiley valves, size 19 mm. All implantations were in the mitral position, except 1 Mitroflow and 1 Ionescu-Shiley prosthesis, which were implanted in the tricuspid position. Moderate or abundant noninfected thrombotic deposits were found on the cusps of 13 of the 33 Mitroflow valves (39%). The Ionescu-Shiley valves shared this tendency, perhaps to a lesser extent, for the formation of thrombus on the valve cusps. Results of transmission electron microscopy, scanning electron microscopy, and calcification analysis are also presented. In this experimental study, the authors did not identify any significant characteristics in the Mitroflow bovine pericardial heart valve prosthesis that would lead to improved or extended durability of this device over the commercially available Ionescu-Shiley bovine pericardial heart valve prosthesis and probably over any other glutaraldehyde-treated bioprosthesis. They would suggest, therefore, that any clinical investigations of the prosthesis be undertaken very cautiously.

Animals↗
PubMed2003

Reduction of postural sway by use of a vibrotactile balance prosthesis prototype in subjects with vestibular deficits.

To evaluate the effectiveness of a prototype vibrotactile balance prosthesis in maintaining balance during dynamic posturography, we studied 6 subjects with unilateral or bilateral vestibular deficit by means of Equitest computerized dynamic posturography (CDP). Their anterior-posterior (AP) sway at the small of the back was measured with a micromechanical rate gyroscope and a linear accelerometer. The resulting tilt estimate was displayed by a vibrotactile array attached to the torso. The vibration served as tilt feedback to the subject. Subject performance was evaluated with the tilt performance index (TPI), which is the inverse of the root-mean-square of tilt. We found that the balance prosthesis reduced the subjects' AP sway. The subjects' results without the balance prosthesis on CDP sensory organization tests (SOTs) 5 and 6 were compared to results with the prosthesis. The average TPI increased significantly (p < .05) when vibrotactile feedback was used as compared to the unaided condition. This finding was true for both SOTs 5 and 6. We conclude that vibrotactile feedback of estimated AP body tilt improved the subjects' ability to perform selected CDP tests. Some of the subjects were able to stand throughout the test with the device turned on, whereas they otherwise constantly fell.

Adult↗
PubMedDate not supplied

Effect of bone block removal and patellar prosthesis on stresses in the human patella.

Thermoelastic stress analysis was used to examine stresses on the anterior surface of patellae after patellar bone block excision for autogenous graft anterior cruciate ligament reconstruction. Complications of anterior cruciate ligament injury often lead to degenerative changes in the knee that can require total knee joint replacement. It was hypothesized that stresses in a bone block-compromised patella may be increased even further by insertion of a patellar prosthesis. All patellae were first tested intact and then were retested after a sequence of surgical modifications including patellar prosthesis implantation, tapered bone block excision, square bone block excision, and both shapes of excised bone blocks with a patellar prosthesis in place. Stresses in patellae with bone blocks excised were significantly greater than stresses in intact patellae. The anterior surface stress pattern in the loaded patella was significantly altered by excision of a bone block. There were no significant differences between maximum stress in patellae with tapered and square bone blocks excised. A finite element analysis showed that excision of a larger trapezoid-shaped bone block greatly increased maximum stress levels. Insertion of a patellar prosthesis did not significantly alter stress patterns or maximum stress levels in the patella.

Adult↗
PubMed2002

Preliminary clinical experience with the Bryan Cervical Disc Prosthesis.

OBJECTIVE: The concept of accelerated degeneration of adjacent disc levels as a consequence of increased stress caused by interbody fusion of the cervical spine has been widely postulated. Therefore, reconstruction of a failed intervertebral disc with a functional disc prosthesis should offer the same benefits as fusion while simultaneously providing motion and thereby protecting the adjacent level discs from the abnormal stresses associated with fusion. This study was designed to determine whether a new, functional intervertebral cervical disc prosthesis can provide relief from objective neurological symptoms and signs, improve the patient's ability to perform activities of daily living, decrease pain, and provide stability and normal range of motion. METHODS: We conducted a prospective, concurrently enrolled, multicenter trial of the Bryan Cervical Disc Prosthesis (Spinal Dynamics Corp., Mercer Island, WA) for the treatment of patients with single-level degenerative disc disease of the cervical spine. Patients with symptomatic cervical radiculopathy and/or myelopathy underwent implantation with the Bryan prosthesis after a standard anterior cervical discectomy. At scheduled follow-up periods, the effectiveness of the device was characterized by evaluating each patient's pain, neurological function, and range of motion at the implanted level. RESULTS: Analysis included data regarding 60 patients at 6 months with 30 of those patients at 1 year. Clinical success at 6 months and 1 year after implantation was 86 and 90%, respectively, exceeding the study's acceptance criteria of 85%. These results compare favorably with the short-term clinical outcomes associated with anterior cervical discectomy and fusion reported in the literature. At 1 year, there was no measurable subsidence of the devices (based on a measurement detection threshold of 2 mm). Evidence of anterior and/or posterior device migration was detected in one patient and suspected in a second patient. There was no evidence of spondylotic bridging at the implanted disc space. The measured range of motion in flexion-extension, as determined by an independent radiologist, ranged from 1 to 21 degrees (mean range of motion, 9 +/- 5 degrees). No devices have been explanted or surgically revised. CONCLUSION: Discectomy and implantation of the device alleviates neurological symptoms and signs similar to anterior cervical discectomy and fusion. Radiographic evidence supports normal range of motion. The procedure is safe and the patients recover quickly. Restrictive postoperative management is not necessary. However, only after long-term follow-up of at least 5 years will it become clear whether the device remains functional, thus confirming these early favorable results. In addition, the influence on adjacent motion segments can be assessed after at least 5 years of follow-up.

Adult↗
PubMed2005

Fusion around cervical disc prosthesis: case report.

OBJECTIVE AND IMPORTANCE: Cervical arthroplasty is a relatively new method to maintain motion after cervical anterior discectomy. Two cases are presented in which bony fusion occurred around a cervical disc prosthesis. CLINICAL PRESENTATION: A 30-year-old man and a 49-year-old woman underwent a right-sided anterior cervical discectomy because of pain in the right arm resulting from a herniated disc (C5-C6). INTERVENTION: A cervical disc prosthesis (Bryan disc prosthesis) was implanted. Postoperatively, the patients were completely free of pain. At the regular 1- and 2-year follow-up examinations, bony fusion was seen on plain x-rays of the cervical spine. The patients were still completely free of signs and symptoms. CONCLUSION: This is the first report in the literature of bony fusion after cervical arthroplasty with the Bryan disc prosthesis.

Adult↗
PubMed2000

Design of a surface replacement prosthesis for the proximal interphalangeal joint.

A surface replacement finger joint prosthesis was designed specifically for the proximal interphalangeal joint (PIPJ). The two-piece design consisted of a bi-condylar proximal phalangeal head and a conforming bi-concave middle phalangeal base. The bearing surfaces were designed as close to the original anatomy of the PIPJs as possible, using detailed information obtained from a previous anatomical study of 83 PIPJs by the present authors. Four sizes of prosthesis were designed with maximum head diameters of 7, 8, 9 and 10 mm. Fixation of the joint prosthesis was achieved by an interference fit between the stems of semicircular cross-section and the phalangeal bone shafts. The main considerations for the stem designs were the offset from the centre of rotation, angle of inclination, length, and cross-sectional shape and size. It is proposed that the two components will be made from cross-linked polyethylene (XLPE) because it can be injection moulded to produce the complex shapes of the joint prosthesis. In addition, XLPE against itself has shown comparable wear rates with stainless steel against ultra-high molecular weight polyethylene from previous work by Joyce et al.

Biocompatible Materials↗
PubMed2004

Temperature prediction in a finite element model for sliding contact analysis of total hip prosthesis.

A finite-element model for sliding contact in total hip joint prosthesis is presented in this paper. The hip prosthesis studied consists of an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup articulating against cobalt-chrome and alumina-ceramic femoral heads. Various aspects of prosthesis operation were analysed using the finite-element model. For example, bulk material and surface stresses were analysed under varying conditions of elastic modulus, friction coefficient, sliding speed, and radial clearance. The resulting variations of temperature were also recorded. The results obtained from the model are useful in understanding the operating conditions and the causes of wear in the hip prosthesis.

Computer Simulation↗
PubMed2003

Front-loading of Groningen voice prosthesis in alaryngeal patients requiring prosthetic replacement.

The Groningen voice prosthesis can be successfully replaced using the back-loading system. We have attempted to minimize patient stress by developing a front-loading system that does not require insertion of the introducer via the tracheo-oesophageal shunt to the oral cavity or the mesopharyngeal anaesthetization regularly used with the back-loading system. Using our front-loading system, the existing prosthesis is removed, then the posterior portion of the replacement Groningen prosthesis is grasped by a pair of nasal forceps with a small jaw to make an acute angle and inserted into the oesophageal cavity through the shunt at a stroke. All 20 patients who underwent forward-loading replacement of a Groningen (n = 17) or Blom-Singer (n = 3) valve with a Groningen valve tolerated the procedure well and experienced no complications except, in some cases, for minor bleeding just after insertion of the prosthesis. The procedure was completed within 30 seconds.

Humans↗
PubMed2005

Insertion of Provox2 voice prosthesis using the anterograde technique immediately after the secondary tracheoesophageal puncture.

Insertion of a voice prosthesis through the tracheoesophageal puncture (TEP) is one way to restore the voice after total laryngectomy. The second generation Provox voice prosthesis is presently one of the most popular devices. Although TEP can be done primarily, there are many centres that prefer it to be done at a second stage for various reasons. However, secondary TEP for retrograde replacement of prosthesis can be difficult and general anaesthesia is very often necessary. Moreover, the presence of neck stiffness and fibrosis from the surgery or previous radiotherapy could affect the neck extension for proper positioning of the trocar. Similarly, it is difficult to insert the prosthesis if there is stenosis at the pharyngoesophageal segment. We describe a technique in which creation of secondary TEP and insertion of Provox2 is done with local anaesthesia under the same setting. The procedure is well tolerated and can be safely performed on an out-patient basis.

Humans↗
PubMed1992

Successful in vitro growth of human respiratory epithelium on a tracheal prosthesis.

Reconstruction of tracheal defects may be necessary following trauma or oncologic surgery. Defects up to 8 cm can often be repaired using end-to-end anastomosis. Use of a tracheal prosthesis for larger defects has been complicated by recurrent stenosis and infection. Recent animal studies, utilizing a Dacron polyurethane prosthesis suggest that problems with anastomotic stenosis and infection can be controlled. Problems with a central stenosis within the prosthesis persist when used for defects greater than 6 cm. Establishment of a confluent lining of respiratory epithelium is believed to be necessary for successful prosthetic tracheal reconstruction. Using cell culture techniques, we report the first successful seeding and growth of human respiratory epithelium onto a Dacron polyurethane tracheal prosthesis.

Cell Adhesion↗
PubMed1995

Penile gangrene: a complication of penile prosthesis.

A case of superficial gangrene of penis after insertion of a malleable penile prosthesis is presented. In all 4 cases previously reported in the literature, the penile prosthesis had to be removed. We managed this patient conservatively without removing the prosthesis. We suggest that in cases of superficial gangrene of penis without infection the prosthesis may not have to be removed.

Anti-Bacterial Agents↗