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At least 397 records · Page 22Linked to original sources
PubMed2006

Radial head prosthesis after fracture of radial head with associated elbow instability.

INTRODUCTION: Fractures of the radial head and associated elbow instability can be treated with operation with radial head prosthesis. In this study, we evaluate function 1-7 years after implantation and also function after removal of five prostheses. MATERIAL AND METHODS: Eighteen patients with radial head fracture and associated elbow instability were evaluated 3.7 years (1-7) after implantation of a radial head prosthesis. Pain at rest and during activity was measured with a visual analogue scale (VAS). Test of stability and neurological examination was done manually as well as measurement of the range of motion, using a goniometer. Activity of daily living (ADL) was estimated using five questions where the answers were graded between 1 and 3. The patients were asked to grade their general satisfaction according to the following scale; very satisfied, satisfied, not satisfied, disappointed. Plain X-rays were taken and 14 patients agreed to have their elbow strength evaluated using the validated BTE work simulator. RESULTS: Five prostheses had been extracted due to poor range of motion. All these patients improved after extraction. All elbows were stable. No patient with extracted prosthesis had VAS score >2. The mean extension defect for this group was 15 degrees (5-25) compared to the mean extension defect for the 13 patients with the prosthesis still in place 15 degrees (0-40). The highest VAS score for the patients with prosthesis was five but the mean as low as 0.8. In the whole group, 13 patients were pain free. ADL function was good in general. The X-rays of the prostheses, still in place, showed radiolucent lines in 7 of the 13 patients. In the whole group, there was a significant decrease in supination, flexion and extension strength (P<0.01, P<0.01, P<0.05). DISCUSSION: Radial head prosthesis works as a spacer after fracture of the radial head and associated instability. If range of motion is much restricted post-operatively, the prosthesis can be removed with improved function as result.

Adult↗
PubMed1975

Cardiac pathology after valve replacement by disc prosthesis. A study of 61 necropsy patients.

Clinical and necropsy observations are described in 61 patients who had one or more cardiac valves replaced with a discoid prosthesis of the Hufnagel type. The most common (31 percent) cause of death among the 45 patients who died early (less than 65 days after operation) appeared to be prosthetic disproportion; that is, the prothesis was too big for the aorta or ventricular cavity into which it was inserted so that inadequate space was present between the margins of the disc and the endocardium of ventricle or intima of aorta. Prosthetic thrombosis occurred in only 3 of the 45 patients who died early, but poppet movement appeared considerably altered in each. In contrast, thrombi were observed on a prosthesis in 14 of the 16 patients who died late (4 to 47 months [average 21] postoperatively), but in none did the thrombi appear of sufficient size to alter poppet function. Escessive bleeding occurred in 11 (24 percent) of the 45 early deaths and was primarily related to the insertion of a patch in the root of the aorta. Uncorrected valvular disease either by itself or by its ability to alter function of the prosthesis appeared responsible for death in 6 (13 percent) of the 45 patients who died early and in 2 (6 percent) of the 16 who died late. Insertion of a mitral poppet disc in a patient with uncorrected aortic regurgitation, even of mild degree, may be hazardous because the aortic regurgitant jet stream may interfere with proper function of the mitral disc. Likewise, insertion of a poppet disc only in the aortic valve position in a patient with combined aortic and mitral regurgitation may considerably increase the degree of mitral incompetence because the aortic prosthesis is intrinsically obstructive. Disc wear or variance was observed in all but one prosthesis in place for more than 1 year. Although hemolytic anemia of significant degree was not observed in any of the 16 patients who died late, the occurrence of renal hemosiderosis in 13 of the 16 patients indicates that the poppet disc prosthesis is considerably traumatic to erythrocytes. Thus, this type of prosthesis is not an ideal substitute cardiac valve. It clots, despite anticoagulant therapy, it is intrinsically stenotic, portions of it, that is, the disc, degenerate, and it causes hemolysis to erythrocytes.

Adult↗
PubMed1990

Long-term prosthesis-related and sudden cardiac-related complications after valve replacement for aortic stenosis.

Predictability of prosthesis-related and sudden cardiac-related complications was examined in 630 patients who were alive 30 days after valve replacement (1965 to 1986) for aortic stenosis. Follow-up totaled 4,072 patient-years. A variety of prosthetic valves, mainly mechanical, were used. The Cox regression model was used to identify independent risk factors and to estimate predicted event-freedoms relative to combinations of these risk factors. There were no risk factors for endocarditis (0.5 +/- 0.1 [number of events per 100 patient-years +/- the standard error]). Except for "other" prosthesis-related complications (0.4 +/- 0.1), adversely influenced by porcine bioprostheses (n = 15) and by the Lillehei-Kaster prosthesis (n = 25), only factors underlying diseased preoperative patient/cardiac status had predictive influence. Predicted 10-year event-freedoms for low-risk versus high-risk estimate were 86% versus 73% for thromboembolism (1.7 +/- 0.2), 95% versus 32% for anticoagulant-related hemorrhage (2.4 +/- 0.2), 69% versus 36% for all prosthesis-related complications (5.0 +/- 0.4), 93% versus 0% for sudden cardiac-related events (myocardial infarction and arrhythmia) (1.8 +/- 0.2), and 66% versus 0.5% for combined prosthesis-related and sudden cardiac-related morbidity and mortality (6.8 +/- 0.4). In 193 patients with coronary arteriography, coronary artery disease was a significant risk factor for each of the complication modalities examined except other prosthesis-related complications, prosthesis replacement, and endocarditis. Deciding to operate early in the course of aortic stenosis might "actively" reduce the rate of these complications.

Adult↗
PubMed1989

Performance assessment of the Terry Fox jogging prosthesis for above-knee amputees.

The Terry Fox jogging (TFJ) prosthesis was developed at Chedoke-McMaster Hospital to alleviate the asymmetric jogging pattern experienced by above-knee amputees when attempting to jog with conventional walking prostheses. This prosthesis features a spring-loaded, telescoping shank designed to eliminate any vaulting action and control the trunk motion during stance. The spring is intended to attenuate the impact forces and release its stored energy at push-off to provide momentum transfer to the jogger. This prosthesis was comprehensively assessed in the gait laboratory, by evaluating the kinematics, energy and power flow patterns of an above-knee amputee jogger wearing the TFJ prosthesis. Included in the assessment is the ability of the prosthesis to satisfy a set of relevant design criteria that have been established from non-amputee jogging patterns. An increased swing phase time for the prosthetic limb and the need to have the knee hyperextended throughout the stance phase contributed to an asymmetric jogging style. The telescoping action did lower the amputee's centre of mass, thereby reducing the vaulting effect. However, the spring only imparted a lifting action to the jogger and the ground reaction forces were double those of a non-amputee jogger. These findings clearly indicate a need to redesign the TFJ prosthesis and are being incorporated in the design of a new physiological jogging prosthesis.

Adult↗
PubMed1986

Operative approach for secondary placement of penile prosthesis.

Secondary placement of penile prosthesis was done in 8 patients following removal of the primarily placed prosthesis for extrusion and infection. Exposure of the corpora cavernosum along its entire length facilitated placement of semirigid prosthesis in each of these patients. The postoperative result was functional in all cases with a normal size in girth and parallel alignment of the distal tip of the prosthesis. In each case the secondarily placed prosthesis was shorter than the primarily placed prosthesis, and the amount of decrease in length appeared to be dependent on the severity of the complication that led to the removal of the primarily placed prosthesis.

Erectile Dysfunction↗
PubMed1994

Morphological, physical and chemical evaluation of the Vascugraft arterial prosthesis: comparison of a novel polyurethane device with other microporous structures.

In this study the morphology, physical properties, surface chemical characteristics and microstructure of the Vascugraft arterial prosthesis have been investigated. This is a novel microporous polyurethane device, recently developed by the company Braun-Melsungen AG in Germany for use as a small calibre arterial substitute. This comparative study included two other synthetic grafts: the Mitrathane prosthesis, a hydrophilic prototype polyetherurethane urea graft with closed internal pores, and the commercially successful expanded polytetrafluoroethylene reinforced Goretex prosthesis with an open microporous structure. The Vascugraft prosthesis contains a network of fused microfibres of varying thickness and orientation which provide open and communicating pores similar in size to those in the Goretex material. In addition, they extend from one side of the graft wall to the other. As well as having superior longitudinal and radial compliance to the reinforced Goretex device, the Vascugraft prosthesis has more than adequate bursting and suture retention strengths. Through the use of contact angle measurements, electron spectroscopy for chemical analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and molecular weight analysis by size exclusion chromatography, the surface of the Vascugraft prosthesis has been shown to be uniquely hydrophobic, as well as containing carbonate groups within an aliphatic polyesterurethane polymer. In addition, variations in micro-phase separation structure of hard and soft segment domains between different sizes and batches of product are marginal. Because of the interesting physical and chemical properties, it is recommended that in vitro biocompatibility and biostability studies be undertaken prior to using the prosthesis in animal or clinical trials.

Animals↗
PubMed1991

Planning of radiotherapy for patients with hip prosthesis.

The effects of a hip prosthesis on the dose distribution when treating pelvic cancer have been evaluated. A prosthesis of titanium alloy in a water phantom was used as a model. Photon radiation beams with energies of 6, 20, and 50 MV and with a focus phantom distance of 100 cm were directed against the prosthesis. The dose profiles at different depths were measured with the RFA-7 system. The sphere of the prosthesis was inhomogeneous. The dose in a beam behind the prosthesis was reduced with the order of 10-40% and the largest distortion was behind the shaft. Using an opposed four-field technique with the same weight on all the fields, the dose reduction was as large as 7-12% in a string across the target behind the end of the shaft. With 50% weight on the lateral fields, the dose reduction was 4-8% of the average dose. Such an uneven dose distribution may decrease the curability, and a treatment technique not including the prosthesis should be preferred. Finally, a local increase of the dose close to the prosthesis seems to be of limited practical concern even at the highest energies.

Hip Prosthesis↗
PubMed2005

The effect of three-dimensional shape optimization on the probabilistic response of a cemented femoral hip prosthesis.

Probabilistic analyses allow the effect of uncertainty in system parameters on predicted model performance measures to be determined. Furthermore, using performance functions to describe a failure event, the probability of failure can be quantified. The effect of three-dimensional prosthesis shape optimization on the probabilistic response and failure probability of a cemented hip prosthesis system is investigated. Random variables include joint and muscle loading, cortical and cancellous bone and PMMA bone cement elastic properties, and strength parameters describing failure of the bone cement and the prosthesis-bone cement interface. Several performance functions describing the bone cement and prosthesis-cement interface are used to compute the probability of failure. When evaluated deterministically, most performance functions indicated a safe design, with the exception of interface tensile failure. However, when evaluated probabilistically, finite probabilities of failure were computed, some significant. The most likely mode of failure before shape optimization was prosthesis-bone cement interface tensile failure with a predicted probability of failure of 97.9%. Deterministic prosthesis shape optimization reduced the probability of failure for all performance functions and reduced prosthesis-bone cement interface tensile failure by 31.7%. Probability sensitivity factors indicate that the uncertainty in the joint loading, cement strength, and implant-cement interface strength have the greatest effect on the computed probability of failure. Implant shape optimization results in a more robust implant design that is less sensitive to uncertainties in joint loading, which cannot be easily controlled, and more sensitive to cement and interface properties, which are easier to modify.

Cementation↗
PubMed2006

Early ocular prosthesis insertion improves quality of life after enucleation.

BACKGROUND: The aim of this study was to evaluate early insertion of ocular prostheses for aesthetic rehabilitation after enucleation and review current methods of enucleation surgery. METHODS: Twelve patients with large intraocular malignancies were treated by enucleation with implant. At the end of surgery, a medium-size conformer was inserted onto the closed conjunctival wound (just before applying a pressure dressing). The pressure dressing was removed 3 to 5 days after surgery. Immediately after bandage removal, the patients saw themselves in a mirror and were offered placement of a relatively small ocular prosthesis. Patients were asked if they preferred their aesthetic appearance with or without the prosthesis. RESULTS: Eight patients (67%) tolerated introduction of the prosthesis at the time of removal of their pressure dressing (3 to 5 days after enucleation surgery). Because of discomfort, 4 were able to receive their prostheses at their second postoperative visit (day 12 or 13). The manipulation at prosthesis insertion and subsequent wearing was found to have no effect on wound closure, final prosthetic fittings, or movement of the permanent prosthesis. All patients were pleased with the cosmetic benefit afforded by early introduction of the prosthesis and preferred their appearance to that of their eye with the conformer. CONCLUSIONS: Early replacement of the conformer by an ocular prosthesis allows for cosmetic rehabilitation and improved quality of life.

Adult↗
PubMed1998

Treatment outcome after radical prostatectomy is not adversely affected by a pre-existing penile prosthesis.

OBJECTIVES: To report on the safety of radical retropubic prostatectomy (RRP) in patients with a penile prosthesis presenting with clinically localized prostate cancer. METHODS: From January 1990 to December 1997, 8 consecutive men with a penile prosthesis underwent RRP for clinically localized prostate cancer. Retrospective data regarding patient population, operating time, estimated blood loss, length of hospital stay, and clinical outcome were evaluated. RESULTS: Mean patient age was 65.4 years (range 57 to 70) at the time of RRP, with a mean preoperative serum prostate-specific antigen level of 11.5 ng/mL. Mean duration of RRP surgery was 183.9 minutes, and the mean estimated blood loss was 1281.8 mL. No complication requiring penile prosthesis removal occurred. In 1 case, the reservoir tubing was punctured during closure of the abdominal fascia wall. This was immediately recognized and fixed. All patients had a functioning penile prosthesis after RRP. CONCLUSIONS: RRP can be safely and expeditiously performed in patients with a pre-existing penile prosthesis. The risk of prosthesis malfunction after RRP is very low. Patients with a penile prosthesis and prostate cancer should not be denied the option of undergoing RRP.

Aged↗
PubMed1996

Results of disc prosthesis after a minimum follow-up period of 2 years.

STUDY DESIGN: This study analyzed retrospectively 46 patients undergoing artificial disc replacement. OBJECTIVE: To assess the clinical and radiographic outcomes of patients who had Charitè SB III disc prosthesis. SUMMARY OF BACKGROUND DATA: Results of disc prosthesis have been reported only at very short-term follow-up periods; preoperative diagnosis and criteria used to evaluate the clinical outcomes were not reported. METHODS: Forty-six patients who had had a disc prosthesis were evaluated clinically and radiographically at least 2 years after surgery. Preoperative diagnosis included disc degeneration in 22 patients and failed disc excision in 24 patients. Disc prosthesis was implanted at a single vertebral level in 36 patients and at two levels in 10 patients. Follow-up evaluation was performed after an average of 3.2 years (range, 2-5 years). RESULTS: Sixty-three percent of patients reported satisfactory results. The success rate was 69% in patients who underwent isolated disc replacement and 77% in those with no previous back surgeries. Seven patients who had unsatisfactory results underwent posterolateral fusion without removing the artificial disc. Two patients underwent removal of the prosthesis. No failure of the implants or loosenings or wear of the polyethylene core were found. Vertebral motion averaged 9 degrees at the operated levels and 16 degrees at the adjacent levels. CONCLUSION: A wrong surgical indication, rather than failure of the prosthesis, appears to be the main cause of unsatisfactory results of disc replacement at medium-term evaluations. Prospective and longer term studies are needed to establish whether disc prosthesis may offer advantages compared with spinal fusion.

Adult↗
PubMed2002

Laser stapedotomy minus prosthesis (laser STAMP): absence of refixation.

OBJECTIVE: To determine what percentage of patients with otosclerosis could successfully undergo a laser stapedotomy minus prosthesis over a 5-year period, and to determine the percentage of patients in whom refixation develops during follow-up. STUDY DESIGN: Retrospective case review of 136 patients (137 ears) who underwent primary surgery for otosclerosis. SETTING: An otology/neurotology tertiary referral center. PATIENTS: Patients were chosen if they had clinical evidence of otosclerosis without a history of otologic surgery. INTERVENTIONS: A standard stapes approach was used for all patients. For the laser stapedotomy minus prosthesis, a hand-held laser probe was used to vaporize the anterior crus of the stapes and perform a linear stapedotomy across the anterior one third of the footplate. If otosclerosis was confined to the fissula ante fenestram, the stapes became completely mobile. The stapedotomy opening was sealed with an adipose tissue graft from the ear lobe. MAIN OUTCOME MEASURES: Pure-tone audiometry with appropriate masking and auditory discrimination testing was performed before surgery, 6 weeks after surgery, and every year thereafter. RESULTS: Of the 137 cases, favorable anatomy and minimal otosclerosis allowed 46 (33.6%) of these patients to undergo laser stapedotomy minus prosthesis. Fifty-seven patients (41.6%) could not undergo the procedure because of extensive otosclerosis. The remaining 34 patients (24.8%) did not receive laser stapedotomy minus prosthesis because of other anatomic or technical difficulties. Of the 34 patients in the laser stapedotomy minus prosthesis group with more than 4 months follow-up, the average air-bone gap was closed from a mean of 22 dB (SD 10 dB) to 6 dB (SD 4 dB) 6 weeks postoperatively. Follow-up periods ranged from 5 months to 53 months (mean 767 days, SD 437 days). The long-term air-bone gap improved slightly to an average of 5 dB (SD 6 dB) in comparison with the sixth postoperative week value. CONCLUSION: Laser stapedotomy minus prosthesis is a minimally invasive procedure, which over the follow-up period has a very low incidence of refixation, as evidenced by a lack of progressive conductive hearing loss. The success of this procedure depends on the correct selection of cases. This procedure has been successfully performed on 33.6% of patients undergoing primary stapes surgery. Laser stapedotomy minus prosthesis seems to be a viable alternative to conventional stapedotomy that yields good results without evidence of refixation over an extended time.

Adipose Tissue↗
PubMed2004

Transmetatarsal amputation prosthesis with carbon-fiber plate: enhanced gait function.

OBJECTIVE: To determine whether the design of a transmetatarsal amputation prosthesis with a carbon-fiber plate would improve gait pattern in patients with transmetatarsal amputations. DESIGN: In the gait laboratory in a tertiary medical center, eight male patients with transmetatarsal amputations were recruited. Nine able-bodied male volunteers were recruited as the control group. A full-length standard shoe and a transmetatarsal amputation prosthesis with a carbon-fiber plate were the footwear used. Our transmetatarsal amputation prosthesis included a custom-molded insole, a mounted toe filler, and a thin, lightweight, carbon-fiber plate incorporated directly beneath the insole. RESULTS: After wearing the transmetatarsal amputation prosthesis with a carbon-fiber plate, the results of the kinetic and kinematic studies were summarized. CONCLUSION: The transmetatarsal amputation prosthesis with a carbon-fiber plate improved gait pattern significantly in patients with transmetatarsal amputations. Drastic shoe modifications are not necessary to have the prosthesis inserted. The carbon-fiber plate functions like the spring-steel shank within the sole of the shoe. The carbon-fiber plate, the toe filler, and the total-contact insole are all mounted as a whole to ensure better foot contact. Therefore, our transmetatarsal amputation prosthesis with a carbon-fiber plate can be a good alternative choice of footwear in patients with transmetatarsal amputations.

Adult↗
PubMed2002

Change in a maxillo-facial prosthesis material effecting from environmental factors: a clinical report.

The purpose of this study was to indicate change in an auricular prosthesis resulting from environmental factors. An auricular prosthesis was made from a commercially maxillo-facial dental materials. The patient used this prosthesis. After one year, the auricular prosthesis was changed, it was nonesthetic. The prosthesis was made over again from the beginning. The prosthesis was changed from environmental factors such as sunlight, wetting and drying, cleaning and secretions. Facial prosthesis was fabricated anew because of color changes and surface changes.

Ear↗
PubMed1997

The fixed/detachable implant provisional prosthesis.

Interim modification and management of a complete denture following surgical uncovering of dental implants can be time-intensive and may fail to provide adequate patient benefit until the definitive prosthesis can be completed. Inadequate interim management can result in functional and tissue difficulties. Modification of the conventional complete denture to a fixed/detachable provisional prosthesis in a one-stage procedure provides the patient an opportunity to experience a fixed prosthesis. The incorporation of fixed, provisional cylinders to the existing denture base using autopolymerizing acrylic resin with a closed-mouth technique is described. The peripheral regions are reduced and the distal extension shortened to resemble a fixed/detachable prosthesis. This conversion technique can provide patient satisfaction and comfort until delivery of the definitive prosthesis. Esthetic concerns, home care problems, or patient difficulties with the provisional prosthesis can be rectified in the final prosthesis.

Dental Abutments↗
PubMed1995

Transesophageal echocardiography for the diagnosis and management of nonobstructive thrombosis of mechanical mitral valve prosthesis.

BACKGROUND: Diagnosis of a mechanical mitral valve prosthesis thrombosis is currently made with transthoracic Doppler echocardiography and occasionally with fluoroscopy. However, identifying a thrombus on a valve prosthesis may be difficult, especially if the thrombus is nonobstructive. To prospectively define the role of transesophageal echocardiography for identification of nonobstructive thrombi, we studied a series of patients in whom the prosthetic valve was considered to function normally on clinical examination and transthoracic echocardiography. METHODS AND RESULTS: One hundred fourteen consecutive patients with mechanical mitral valve prosthesis were investigated by both transthoracic echocardiography and transesophageal echocardiography. These examinations were performed for recent systemic emboli (15 patients), fever of unknown etiology (11 patients), routine postoperative evaluation (56 patients), and other reasons (32 patients). Based on transthoracic echo diagnosis, all prostheses were considered normal. Yet, in 20 patients transesophageal echocardiography revealed the presence of a 2- to 15-mm-long mobile thrombus localized on the atrial surface of the prosthesis. When compared with the remaining 94 patients with no visible thrombi, there was no significant difference between the two groups in terms of incidence of atrial fibrillation (65% versus 52%), left atrial size (48 +/- 9 versus 51 +/- 13 mm), left ventricular end-diastolic diameter (49 +/- 10 versus 51 +/- 13 mm) and fractional shortening (28 +/- 9% versus 31 +/- 10%), presence of spontaneous contrast to the left atrium (40% versus 41%), transprosthetic mean pressure gradient (4.0 +/- 1.4 versus 3.9 +/- 1.5 mm Hg), or the type of prosthesis used. After we discovered a nonobstructive thrombosis, patients were treated with heparin (n = 9) or oral anticoagulation (n = 11). The presence of a localized thrombus was confirmed in 3 patients who were operated on. In the present study, evolution appeared to depend on thrombus size: of 14 patients exhibiting a small (< 5 mm) thrombus, 10 had an uneventful course, whereas 5 of 6 patients with a large (> or = 5 mm) thrombus developed complications or died. CONCLUSIONS: Transesophageal echocardiography appears to be a reliable method to diagnose thrombi on a mechanical mitral valve prosthesis, even when transthoracic Doppler echocardiographic parameters appear to be normal. Transesophageal echo assessment of thrombus size may be helpful in deciding whether a patient with mitral prosthesis should be treated by anticoagulation, thrombolysis, or valve rereplacement.

Adult↗
PubMed1998

Loading of a unilateral temporomandibular joint prosthesis: a three-dimensional mathematical study.

The load on the prosthetic side and the influence of the design on the remaining natural contralateral TMJ must be known before a unilateral temporomandibular joint (TMJ) prosthesis can be developed. The aim of the present study was to determine the maximum loading of the TMJ prosthetic side and the natural contralateral TMJ and to investigate the influence of the location of the center of rotation of the prosthesis on the maximum loading. For this purpose, a mathematical model of the mandible with a unilateral TMJ prosthesis with a fixed center of rotation (CR) was developed. The location of the CR of the TMJ prosthesis was varied from the middle of the natural mandibular condyle to 15 mm inferior to this location. Although the maximum joint reaction forces changed as a result of a unilateral TMJ prosthesis, the trend of the loading curves was similar to that of an intact mandible. A unilateral TMJ prosthesis resulted in a 50% higher loading of the prosthetic side, while the load on the natural contralateral TMJ remained within normal limits. The maximum load on the prosthetic side occurred during molar bites and could reach 100 N in the cranial direction, 30 N in the ventral direction, and 25 N in the medio-lateral direction. The location of the CR did not have a significant influence on the loading of the TMJ prosthesis and the natural contralateral TMJ.

Adult↗
PubMed1997

In vivo aerodynamic characteristics of the Nijdam voice prosthesis.

The Nijdam voice prosthesis is an indwelling valveless voice prosthesis for postlaryngectomy voice rehabilitation. The in vitro aerodynamic characteristics are reported to be comparable to that of the low-resistance Groningen voice prosthesis. Owing to the design of the prosthesis the airflow resistance depends on the shaft length of the voice prosthesis in relation to the thickness of the tracheo-oesophageal wall. As tissue characteristics of the patient's oesophageal mucosa could also be of importance, an in vivo study was found necessary. To assess in vivo characteristics the following parameters were recorded in 10 patients: intratracheal pressure, intraoesophageal pressure and airflow during phonation. At an airflow of 0.15 1/sec the transdevice pressure loss varied from 0.5 up to 7 kPa (mean 3.9 kPa). With an artificial increase of the tracheo-oesophageal wall thickness, transdevice pressure losses up to 13 kPa were found. Significant interindividual as well as intraindividual differences were noted. The airflow resistance of the Nijdam voice prosthesis in relation to the thickness of the tracheo-oesophageal wall was compared with the airflow resistance reported for various other voice prostheses. The in vivo aerodynamic characteristics of the Nijdam voice prosthesis found in this study indicate the need to modify the present design in order to improve its airflow resistance and to eliminate the influence of the thickness and tissue characteristics of the tracheo-oesophageal wall.

Airway Resistance↗