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Experimental carinal replacement with an Y-shaped collagen-conjugated prosthesis.

BACKGROUND: A new prosthesis was designed for reconstruction of the bifurcation of the trachea and used for experimental carinal replacement in dogs. METHODS: The main Frame of the new prosthesis consists of Y-shaped Marlex mesh tube reinforced with polypropylene spirals. It is coated with collagen extracted from porcine skin to provide biocompatibility and airtightness. Carinal replacement with omentopexy was performed in 17 dogs. RESULTS: Seven dogs survived the postoperative period, and 10 dogs died within 11 days after the operation. The main causes of early postoperative death were fistula and air leakage from the prosthesis. Causes of late postoperative death were obstruction of the main bronchus (two) and lung abscess (one). The four long-term survivors had no stenosis or dehiscence until they were sacrificed 15 months after the operation. Histological examination of these dogs revealed that the luminal surface was covered either with ciliated columnar epithelium or non-ciliated squamous epithelium. CONCLUSIONS: The study results suggest the possibility of successful prosthetic carinal reconstruction with epithelial regrowth using this Y-shaped prosthesis.

Animals↗

25 years follow-up of patients after replacement of the aortic valve with a Smeloff-Cutter prosthesis.

Thirty years ago the Smeloff-Cutter double-caged ball prosthesis was developed for aortic valve replacement. Between 1967 and 1977 a total of 46 patients admitted to the University Hospital Munich underwent an isolated aortic valve replacement with the Smeloff-Cutter prosthesis. Postoperatively all patients received anticoagulation treatment with phenprocoumon (Marcumar). A retrospective follow-up of 95.6% of patients, representing 842 patient years, was completed. The corresponding actuarial survival rates after 10, 20, and 25 years were 69.1%, 47.4%, and 31.4%. The actuarial freedom rates from either valve-related complications, reoperations, or death were 72.9%, 47.4%, and 20.3%. Thromboembolism occurred in 1.41% per patient year, bleeding in 1.90%. The rates of valvular dysfunction, reoperation, and endocarditis were 1.16%, 1.16%, and 0.2% per patient-year. Today, of the surviving patients 81% are in NYHA Class I or II, 19% in NYHA Class III. No surviving patient deteriorated over the reported time in his or her functional NYHA classification. After 25 years the Smeloff-Cutter valve has proved to be a reliable prosthesis for aortic valve replacement and-together with the Starr-Edwards prosthesis-it has set a standard in longterm durability by which all other valve designs will have to be measured.

Adolescent↗

[The patella following implantation of a knee prosthesis, with reference to patella plasty (author's transl)].

The follow-up patella using knee prosthesis depends on the followings: a) advancement of femoropatellar arthrosis, b) shape and kind of surface of the fossa patellaris femoris, c) kind of knee prosthesis. To treat the patella arthrosis patella plasty is a good alternative to a patella prosthesis. This has been noticed by good or very good results 34 Patients out of 43. It has no complications and does not prevent the use of patella prosthesis if necessary.

Bone Regeneration↗

The anterior cantilever in the implant-supported screw-retained mandibular prosthesis.

STATEMENT OF PROBLEM: When implants are placed interforaminally in mandibular implant-supported screw-retained prostheses, the most anterior implant is usually positioned lingual to the incisors of the prosthesis. This creates an anterior cantilever with the entire prosthesis acting as a class I lever and possibly placing the anterior implant under alternating tension and compression during function. PURPOSE: The purpose of this study was to measure the anterior cantilever of randomly chosen patients with restored mandibular implant-supported fixed prostheses, and to establish the proportions of anterior to posterior cantilever lengths relative to the anteroposterior spread. MATERIAL AND METHODS: Thirteen edentulous patients were recruited from the University of Minnesota's dental implant program. Each patient had been restored with a maxillary complete denture and a mandibular implant-supported screw-retained prosthesis supported by 5 endosseous implants. Each patient had 1 mandibular impression made with irreversible hydrocolloid, which was poured in type III gypsum. A FaroArm precision 3D measuring stylus was used to make multiple-axis (X-Y-Z) measurements (mm) on the casts of the dental implants, of anteroposterior spread, and anterior and posterior cantilevers. Presence or absence of screw loosening was noted using a screwdriver with finger pressure. Data were analyzed using a 1-way analysis of variance to compare prostheses with loose screws to prostheses without loose screws, for each of 3 outcome measures: length of anterior cantilever, length of posterior cantilever, and anteroposterior spread (P<.05). RESULTS: Mandibular anterior cantilever lengths ranged from 5.5 to 14.4 mm with a mean of 8.78 mm. Combined posterior cantilever lengths ranged from 9.2 to 20.9 mm with a mean of 16.2 mm. Anteroposterior spread ranged from 5.2 to 12.3 mm with a mean of 7.9 mm. From a total of 65 retaining screws, 7 were found to be completely loose. No apparent correlation was found between length of mandibular anterior cantilever and screw loosening (P=.45), although the ratio of posterior cantilever to anteroposterior spread (2:4) was significantly associated with screw loosening (P=.006). CONCLUSION: Within the limitations of this study, anterior cantilevers in mandibular implant-supported screw-retained prostheses were frequent and appeared to depend on implant placement and prosthesis design. The ratio of anterior to posterior cantilever lengths was approximately 1:2.

Aged↗

Engagement in activities revealing the body and psychosocial adjustment in adults with a trans-tibial prosthesis.

The purpose of this study was to examine the effects of the appearance of a prosthesis on social behaviour, social discomfort and psychological well-being in eleven amputees taking delivery of a prosthesis with a silicone cover. Two new scales were developed: the 'Engagement in everyday activities involving revealing the body' (EEARB); and the 'Discomfort-Engagement in everyday activities involving revealing the body' (Discomfort-EEARB) scales. The psychometric properties of these scales were determined using a sample of 101 able-bodied adults. The Hospital Anxiety and Depression Scale and the Rosenberg Self-Esteem Scale were also used to measure psychological well-being in the amputee sample. The EEARB and Discomfort-EEARB proved to have good reliability and validity. Comparison of amputees' scores prior to receiving the silicone cosmesis with those of the able-bodied adults revealed significant behavioural limitations and social discomfort, associated with low self-esteem, anxiety and depression. There was a significant increase in amputees' scores three months afier taking delivery of their prosthesis, indicating that amputees reported engaging in more activities which involved revealing their body, and that they would feel more comfortable in situations which involved revealing the body. As the amputee sample available was small and self-selected, it is not possible to generalise these findings to the amputee population as a whole. However, since there is little previous research investigating the effects of the appearance of the prosthesis, these findings demonstrate the need for further research in this area.

Activities of Daily Living↗

Treatment of sequelae of radial head fractures with a bipolar radial head prosthesis: good outcome after 1-4 years follow-up in 11 patients.

BACKGROUND: In the presence of additional disruption of the distal radioulnar ligaments, the interosseous membrane, or the lateral- and/or medial collateral ligament, radial head fractures treated by resection will result in valgus elbow instability, proximal radial migration and/or posterolateral rotatory instability. Radial head replacement has been used to treat or prevent this. We report our experience with the Judet CRF II radial head prosthesis. PATIENTS AND METHODS: We treated 11 patients with a bipolar radial head prosthesis because of elbow instability after previous treatment for Mason-Johnston type III or IV radial head fractures. The outcome was assessed clinically using two standardized elbow function assessment scales, and radiographically after a mean follow-up of 2 years. RESULTS: Clinical outcome was either good or excellent in all patients; all elbows were stable. Radiographically, there were no signs of loosening, fracture or heterotopic ossification. 2 patients required reoperation for subluxation of the prosthesis; both were treated by reducing the size of the modular head of the prosthesis. There was erosion of the capitellum in 1 patient. INTERPRETATION: Bipolar radial head replacement can be used successfully for treatment of the sequelae of radial head fractures. The long-term outcome is, however, unknown.

Adult↗

Outcome of penicillin-susceptible streptococcal prosthetic joint infection treated with debridement and retention of the prosthesis.

Debridement with retention of the prosthesis was the initial treatment modality for 19 cases of penicillin-susceptible streptococcal prosthetic joint infection that occurred in 18 patients who presented to the Mayo Clinic (Rochester, Minnesota) during 1969-1998. All of the cases of prosthetic joint infection occurred >30 days after implantation of the prosthesis, which was well fixed at the time of debridement. The median duration of symptoms before debridement was 4 days (range, 1-10 days). Treatment failure (defined as relapse of infection with the original microorganism) occurred in 2 cases (10.5%) during a median follow-up period of 3.9 years (range, 0.3-21.7 years). The 1-year cumulative risk of relapse was 11% (95% confidence interval, 0%-26%). Relapse of prosthetic joint infection due to penicillin-susceptible streptococci after debridement and retention of the prosthesis is uncommon. For patients who present with a well-fixed prosthesis and a short duration of symptoms, debridement with retention appears to be an effective treatment modality.

Adolescent↗

Mechanical effect of the Angelchik prosthesis on the competency of the gastric cardia: pathophysiologic implications and surgical perspectives.

The Angelchik prosthesis appears to be effective in preventing gastroesophageal reflux, although its precise mechanism of action remains controversial. In a unique in vitro model, 10 freshly harvested canine esophagogastric specimens were tested for their ability to remain competent against challenges of intragastric pressure under controlled conditions of intra-abdominal pressure, longitudinal esophageal tension, lower esophageal sphincter pressure and overall length and circumference of the cardia (measure of gastric dilatation). Competency of the specimen was assessed by stepwise variation in the overall length of the sphincter, while keeping constant intraabdominal pressure (20 cm H2O), intragastric pressure (20 cm H2O), esophageal tension (physiologic), lower esophageal sphincter pressure (15 cm H2O) and degree of gastric dilatation (3 cm). With each specimen serving as its own control, the effect produced by the application of an Angelchik prosthesis was evaluated. Results consistently demonstrated that at any lower esophageal sphincter length the percent of competency was increased when the prosthesis was applied (P < 0.01). The findings indicate that the Angelchik prosthesis controls reflux by preventing unfolding of the lower esophageal sphincter when challenged by intragastric pressure.

Animals↗

Chopart prosthesis and semirigid foot orthosis in traumatic forefoot amputation. Comparative gait analysis.

Gait was analyzed in seven otherwise healthy males at least 11 mo after they had recovered from a traumatic unilateral transmetatarsal amputation incurred during the course of their usual occupation. All seven were fitted with a semirigid foot orthosis. Four were also fitted with a Chopart prosthesis. Gait was evaluated with forceplate measurements of ground reaction force during free walking, by clinical observation of such ambulation on videotape, and by the subjective impression of the men as obtained by a questionnaire. In all men, with unmodified footwear, with the orthosis, and with the prosthesis, the forceplate data showed an abnormal pattern characterized by reduced stance duration and deficient forward propulsion on the amputated side. The abnormality and asymmetry of ground-reaction forces were less with greater preserved stump length and for a given stump length were with the above-ankle concept (Chopart) prosthesis than with the below-ankle concept. These features were recognized during the clinical analysis of all footwear, but there was an extra irregularity of weight progression noted with the fixed ankle of the Chopart prosthesis. The questionnaire reported stump problems to be the principal difficulty, and the follow-up revealed persistent attempts at surgical management including consideration of amputation at a higher level. It was concluded that the patient and the surgeons are likely to choose preservation of limb length over considerations of function during acute care and that the prosthetic concept best suited to deal with the resulting stump should emphasize unloading the distal part of the stump and smoothing out the impulsive force peak on the stump in late stance to minimize pain and to enhance ambulation capacity.

Adult↗

Stapes prosthesis attachment: the effect of crimping on sound transfer in otosclerosis surgery.

OBJECTIVES/HYPOTHESIS: Although in stapes surgery successful hearing improvement may be achieved in the majority of patients, unsatisfactory closure of the air-bone gap can be recorded. One of many reasons for unexpected failures of stapes surgery may be the insufficient crimping of a stapes prosthesis onto the incus. The objectives of the study were to assess the amount of sound transmission loss in response to the quality of prosthesis crimping and to identify a required loop attachment pattern to obtain good sound transmission results. STUDY DESIGN: Experimental. METHODS: A temporal bone model was developed to measure the sound transmission properties between incus and prosthesis on 17 fresh human temporal bones. The attachment of a titanium stapes piston was assessed without crimping, followed by loose crimping and tight fixation to the incus, using scanning laser Doppler interferometry, endoscopic photography, micro grinding technique, and scanning electron microscopy. An algorithm had to be developed to simulate acoustical stimulation using electromechanical stimulation. RESULTS: Optimal tight crimping of the stapes piston revealed consistent good sound transfer function ranging from 0 to 7 dB loss, and loss remained, on average, at 2 dB. The mean transmission losses for conditions of loose crimping and no crimping were surprisingly small (within 10 dB). However, these unusual crimping conditions allowed a wide range of losses up to 28 dB. A close coupling at least at two opposite points was obligatory to obtain consistently good results. CONCLUSIONS: Perfect hearing reconstruction necessitates ideal crimping of a prosthesis to obtain consistently good results. However, the final functional gain depends on many different intraoperative and postoperative factors.

Acoustic Stimulation↗

Dynaflex prosthesis in total phalloplasty.

Because of the high rate of complications and because voiding while standing is a priority for most female-to-male transsexuals, until recently, I have refrained from implantation of a rigidity prosthesis in total phalloplasty. However, promising results have been obtained with self-contained Dynaflex hydraulic penile implants. The results and complications observed in my first five cases are reported in order to help prevent failure in future cases. I advocate implantation as a secondary procedure after the neophallus has gained sensitivity. The penile prosthesis should be covered by a Dacron prosthesis to ensure optimal encapsulation and collagen ingrowth. Since the neophallus girth will not allow for two prostheses to be implanted, and because properly serviceable crus penis is lacking in female-to-male transsexuals, I further advocate fixation of the one cylinder to the pubic symphysis. For insertion, the neoscrotal approach is superior. I maintain that combination of a neourethra and a rigidity prosthesis in one neophallus remains a challenge, both to the patient and to the surgeon.

Adult↗

Early clinical and radiologic outcomes of cervical arthroplasty with Bryan Cervical Disc prosthesis.

Among 61 patients underwent disc replacement with the Bryan prosthesis, 47 patients were followed more than 3 months and their clinical and radiologic data were retrospectively analyzed to clarify very early clinical and radiologic outcomes and complications of disc arthroplasty with the Bryan Cervical Disc prosthesis during the learning period. Mean follow-up period was 6 months. Mean age was 45.6 years. Single-level procedure was done in 39 patients and 2-level in 8; a total of 55 levels replaced. Neck disability index improved from 59.8% to 22.9%. Visual analog pain score (VAS) of the neck improved from 8.4 to 1.6. VAS of shoulder/arm pain improved from 8.8 to 2.4. Mean patients' subjective improvement rate of symptoms was 71.1%. According to improvement in the neck disability index and VAS (over 50% improvement rate in each parameter), patients' subjective improvement rate (over 50%), and patients' satisfaction, the surgical success was achieved in 39 patients (83%). Eight patients (17%) showed failure. Mean segmental angle became more kyphotic after surgery from -0.7 degree of kyphosis (-11 to 7.7 degrees) to -1.3 degrees (-32 to 20.9 degrees) without statistical significance (P=0.55). Among 24 segments that showed preoperative kyphosis, 13 (54.2%) showed aggravated kyphosis, 7 (29.1%) showed decreased kyphosis and 4 (16.7%) recovered to lordosis. Among 31 segments that showed preoperative lordosis, 19 (61.3%) showed loss of lordosis and 12 (38.7%) showed increased lordosis. Mean range of motion increased significantly after surgery (6.7 to 8.5 degrees, P=0.04). Preoperative and postoperative segmental kyphosis was not related to clinical success. Cervical arthroplasty with the Bryan Cervical Disc prosthesis failed to restore segmental lordotic angle. A concern arises because it is well known that the fusion in kyphotic curvature causes more frequent problems on adjacent levels in anterior cervical discectomy and fusion. For the present, it seems preferable to exclude the patient who already has significant segmental kyphosis from disc arthroplasty with Bryan Cervical Disc prosthesis.

Adult↗

Penile prosthesis cultures during revision surgery: a multicenter study.

PURPOSE: Initial implantation of inflatable penile prosthesis has a 3% risk of infection. Reoperation of penile implants has a higher rate of infection, estimated between 10% and 18%. To explain the higher risk in revision surgery in this prospective study we cultured clinically uninfected prostheses requiring revision. Prosthesis pain was also investigated as a predictor of positive culture. MATERIALS AND METHODS: At 3 institutions cultures were prospectively obtained from 77 clinically uninfected penile prostheses at revision surgery. Immediately upon surgical exposure of the pump cultures were obtained. If a bacterial biofilm was noted on any component it was additionally cultured. All culture isolates positive for a staphylococcus species were tested for sensitivity to rifampin and tetracycline (minocycline). An implant is now available that is coated with these antibiotics. Patient history of chronic prosthesis pain was ascertained. RESULTS: Culture positive bacteria were found in 54 of 77 (70%) patients with clinically uninfected penile prostheses. In some patients more than 1 organism grew and, occasionally, the pump culture was negative but the biofilm was positive. Of 54 patients 49 had positive (90%) culture for staphylococcus genus with 10 different species. All staphylococcal species were sensitive to rifampin and/or tetracycline. We did not find a significant association between prosthesis related pain and culture laboratory results. CONCLUSIONS: The majority of clinically uninfected penile prostheses have organisms growing in the implant spaces at reoperation. Most of these organisms are staphylococcal species that are sensitive to rifampin/minocycline.

Aged↗

Quality of life following simultaneous placement of penile prosthesis with radical prostatectomy.

PURPOSE: The present study examined erectile functioning, frequency of sexual contact, psychological functioning, partner/marital satisfaction and overall quality of life (QOL) after immediate sexual rehabilitation for prostate cancer via simultaneous placement of a penile prosthesis at radical retropubic prostatectomy (RP). MATERIALS AND METHODS: Questionnaire packets were sent to and received from 51 men who had undergone simultaneous implantation of a penile prosthesis at the time of RP (PP+) and from a comparison group of 47 men who undergone RP alone (PP-) matched by age and year of surgery. Questionnaires included the Erectile Dysfunction Inventory of Treatment Satisfaction, the Depression Anxiety Stress Scales, the Dyadic Adjustment Scale and a prostate specific European Organization for the Research and Treatment of Cancer (EORTC) QOL questionnaire. Further comparisons were performed for a PP- subgroup consisting of 15 patients who had undergone nerve sparing RP. RESULTS: Higher Erectile Dysfunction Inventory of Treatment Satisfaction, EORTC Sexual Functioning, EORTC Total scores and more frequent sexual contact were reported by the PP+ group compared with the PP- group. The PP+ group also had better outcomes that approached but did not reach statistical significance compared with the nerve sparing subgroup with regard to Depression Anxiety Stress Scales and EORTC Emotional Functioning scores. CONCLUSIONS: Men who chose simultaneous placement of a penile prosthesis with RP reported greater overall QOL, erectile function and more frequent sexual contact than a comparison group of men who underwent RP alone. Placement of penile prosthesis at the time of RP may be a desirable option for men with prostate cancer in whom a nerve sparing procedure may not be ideal. These results underscore the importance of sexual function for men undergoing prostate cancer treatment.

Aged↗

System design and performance of a unilateral horizontal semicircular canal prosthesis.

We have reported preliminary results regarding a prototype semicircular canal prosthesis and concluded that it can provide rotational cues to the nervous system. This paper presents the system design of the prosthesis, and also reports the prosthesis system performance and effectiveness. The prosthesis delivers electrical pulses to the nerve branch innervating the horizontal semicircular canal on one side via implanted electrodes. To allow us to encode both directions of angular velocity, the baseline stimulation pulse frequency was set at 150 Hz, which is somewhat higher than the average firing rate of afferents innervating the semicircular canals in normal guinea pigs (approximately 60Hz). A sensor measures angular velocity to modulate (increase or decrease) the pulse rate. The prosthetic system was provided to a guinea pig whose horizontal canals were surgically plugged. The animal responded to the baseline stimulation initially and adapted to the baseline stimulation in roughly one day. After this baseline adaptation the animal responded to yaw rotation, showing that the function of the canals was partially restored. The experiments also show that the nervous system adapts to the artificial rotational cue provided via electrical stimulation.

Animals↗

Vocal rehabilitation after total laryngectomy using the Provox voice prosthesis.

Vocal rehabilitation in laryngectomized patients can be attained by surgical (tracheoesophageal speech) or conservative methods (oesophageal speech or artificial larynx). We prospectively studied voice restoration in 37 patients who underwent total laryngectomy in the period from February 1991 to February 1993. The patients were given the opportunity to assess both non-shunt oesophageal speech and shunt oesophageal speech using the Provox voice prosthesis. The Provox low resistance, self-retaining voice prosthesis is a biflanged device made of silicon rubber. A primary tracheoesophageal puncture was made in 28 patients, while a secondary puncture was performed in another nine patients. The results were assessed according to criteria established at the 'Third International Congress on Voice Prosthesis' in Groningen (1988). Functional tracheoesophageal speech after primary puncture was achieved in 95% of patients 12 months after puncture, while oesophageal voice was acquired by 55%. Only minor surgical and prosthesis-related complications were encountered during this follow-up period in 29% of the patients. The device lifetime varied from 3 months to at least 2 years (mean 5.4 months).

Candida albicans↗

Experience with the Melbourne knee prosthesis, based on the first 35 operations over a three-year period.

The Melbourne knee prosthesis is an improved hinge prosthesis. Its component parts are constructed of a chrome cobalt alloy and ultrahigh molecular weight polyethylene. The hinge has a range of flexion of 120 degrees, and while flexed, can rotate 15 degrees in either direction. Over the past three years a total of 45 prostheses have been inserted in patients with chronic degenerative arthritis of the knee joints. This survey covers the first 35 operations. The most gratifying result has been a dramatic relief of pain in 87.5% of patients. There have been few complications, and no prosthesis has had to be removed. There have been no mechanical failures of the prosthesis itself.

Adult↗

An alternative technique for mandibular advancement prosthesis fabrication.

One of the conservative and successful modalities of treatment for obstructive sleep apnea is the mandibular advancement prosthesis. This prosthesis engages teeth on both dental arches for retention and stability. This article describes a technique that allows the fabrication of such a prosthesis in one piece and in a single laboratory step. This may be beneficial in reducing the laboratory time required for fabrication of such a prosthesis.

Dental Prosthesis Design↗