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PubMed1981

[GUEPAR hinge knee prosthesis (author's transl)].

Early and late results of Guepar hinge knee prosthesis have been evaluated on a serie of 184 operations performed before January 1st 1974. There were 3 immediate deaths and 26 before 5 years. 19 prosthesis were removed. 126 knees had degenerative osteoarthritis, 52 rheumatoid arthritis. 22 had been operated on before. Patellar displacement, present in 27 p. 100 of the cases was the most frequent cause of complaint: pain or instability, proportional to the severity of displacement made reoperation necessary in 10 p. 100 of the patients. Addition of a patellar prosthesis was the most successful treatment as far as pain is concerned: it is probably advisable as a primary procedure. Deep infections occurred in 8,3 p. 100 of the cases, unfrequently after 2 years. Healing was obtained in all cases either by revision or by removal and arthrodesis: but functional results were poor except when fusion was achieved, in half of the cases of arthrodesis. Loosening occurred in 16 p 100 of the cases mainly as the consequence of insufficient technique. It was frequently tolerated: reoperation was necessary in 6 p. 100 of the total. Late functional results were evaluated in 99 cases with a follow-up of 5 to 8 years. Apart from loosening, the results did not deteriorate. 60 p. 100 are evaluated as excellent or good, 29 p. 100 fair, and 11 p. 100 bad. With due consideration of these results election of this prosthesis should be limited to special cases. To prevent complications, the use of a patellar prosthesis, of reinforced models, and of cementing under pressure is advisable.

Adult↗
PubMed1981

[Aneurysm formation on dacron prosthesis after 84 months of use. Pathology, structural and chemical evaluation of the explanted device (author's transl)].

A 56 year old patient fitted with a femoro-popliteal Dacron prosthesis (Weavenit-Meadox Medical) 84 months earlier, presented with a severe palpable dilation in the middle part of the graft. The dilated segment of the prosthesis was resected locally and spliced to a new fabric device. The explanted section of prosthesis was analyzed; the dilation was found to extend only over several centimeters near the centre of the prosthesis. The degree of "healing" was found to be satisfactory except in the part which was most distended; this area also revealed mild bacterial colonization. Physico-chemical analysis of the fabric revealed that the dilation had taken place subsequently to hydrolytic degradation of the polyester fibres. Manufacturing conditions may have contributed to predisposing parts of the prosthesis to accelerated biodeterioration in vivo.

Biodegradation, Environmental↗
PubMed1983

Replacement of the knee in rheumatoid arthritis using the Imperial College London Hospital prosthesis (ICLH) 1977-1979.

The Imperial College London Hospital (ICLH) technique and prosthesis for the total replacement of the knee was evolved over the period 1968 to 1977. The results now reported were obtained at The London Hospital on rheumatoid knees operated upon in the period 1977 to 1979. These knees were reviewed and the results published with a one to 2 year follow-up in 1981. In the present paper this review has been extended to 3 to 5 years. We find that in successfully replaced knees the quality of the clinical result has remained unchanged over the extended period of review. Certain further complications have been encountered which are described. These complications have led us to the conclusion that whereas we previously accepted post-operative alignments between one and 10 degrees of valgus, we should now adjust these limits. We now regard a knee having anything less than 5 degrees of valgus post-operatively as having been incorrectly replaced. The limits of valgus can perhaps be extended to 15 degrees. Experience over the period 1977 to 1980 suggested the possibility of further improvements in both the operative technique and the prosthesis. Accordingly the ICLH prosthesis has now been modified. The modified prosthesis (the Freeman-Samuelson prosthesis) is described in this paper but results with it are not reported.

Adult↗
PubMedDate not supplied

The endothelialization process of a fibrous polyurethane microvascular prosthesis after implantation in the abdominal aorta of the rat. A scanning electron microscopic study.

The endothelialization process of a fibrous microvascular polyurethane prosthesis (inner diameter 1.6 mm) was studied by scanning electron microscopy. Forty-seven prostheses (1 cm) were implanted into the abdominal aorta of rats between the left renal artery and the bifurcation. Specimens were taken on day 1, 3, 5, 7, 10, 14, 18, 21 and 25, as well as 6 and 9 months after implantation, to evaluate immediate and delayed response and complications. The patency rate of the implants was 91.2%. After an initial recovery period of five days, endothelial cells started to migrate onto the inner surface of the prosthesis with a velocity of approximately 0.3 mm per day, resulting in a completely endothelialized prosthesis at day 21. A smooth continuous inner lining was achieved. A difference in growth pattern between the proximal and distal growth zone was observed, and may be attributed to the direction of the blood flow through the prosthesis. The endothelial cells advanced in a close arrangement. No cells were seen to settle and grow in between the two growth zones on the fibrin layer. If no immediate complications occur, the endothelialization process (21 days) proceeds uneventfully and no late complications are observed. Though it may be argued that the new cells lack some authentic endothelial features, this study indicates that they are at least of endothelial orgin, and behave morphologically like endothelial cells. It can be concluded that the adequate texture of the prosthesis and the cell anchoring, in combination with both an optimal surgical performance and blood flow, ensure that the microvascular prostheses are rapidly endothelialized and retain high patency rates over long periods of time.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

[Tricuspid valve replacement by Hancock's prosthesis].

The medium term results of tricuspid valve replacement with the Hancock bioprosthesis are reported. Twenty eight patients underwent tricuspid valve replacement with this prosthesis between December 1974 and January 1978: mitral valve replacement with a Starr-Edwards or Cooley-Cutter prosthesis was associated in all cases and aortic valve replacement with a Björk-Shiley prosthesis in 11 cases. Follow-up at an average of 36,2 months after operation examined functional status, cardiac size and haemodynamics (in 12 patients). Three patients died in the immediate postoperative period and four others died later: the number of survivors was greater in the triple valve replacement (9/11) than in the double valve replacement group (12/17) but the difference was not statistically significant. Of the 23 surviving patients (average follow-up of 36,2 +/- 9,6 months), 17 were classified in functional Classes I or II of the NYHA classification. All patients had been Class III or IV before operation. The cardiothoracic ratio did not decrease significantly in patients undergoing triple valve replacement. Control cardiac catheterisation showed a significant increase in cardiac index (2,53 +/- 0,11 1/mn/m2, compared to 1,87 +/- 0,35 1/mn/m2 before operation; p less than 0,001) without significant reduction in pulmonary artery or right atrial pressures. The resting gradient across the Hancock bioprosthesis was not related to the size of the prosthesis (No 29-30: 2,17 +/- 2,57 mm Hg; No 31-33: 2,78 +/- 3,53 mm Hg) or with the quality of the functional result. However, on exercise, the gradient across the prosthesis was high, reaching an average of 10,3 +/- 5,2 mm Hg). The operative mortality of tricuspid valve replacement is relatively bioprosthesis associated with mitral and/or aortic valve replacement is relatively bioprosthesis associated with mitral and/or aortic valve replacement is relatively low (about 10%) and could be an argument in favour of broadening the indications for tricuspid valve replacement as resting tricuspid function with a bioprosthesis is satisfactory. However, the stenotic effects on exercise and the uncertainty over the long-term outcome of bioprostheses suggest that surgery should be limited to severe tricuspid stenoses and/or major tricuspid regurgitation organic or functional uncontrolled by digitalis and diuretic therapy.

Adult↗
PubMed1982

Thrombectomy: surgical treatment of the thrombosed Björk-Shiley prosthesis. Report of seven cases and review of the literature.

Among 1,000 patients with 1,225 Björk-Shiley prostheses, we have detected 12 cases (0.98%) of late thrombosis of the Prosthesis, seven of which were successfully managed by thrombectomy. A review of other authors' experience with this procedure shows no deaths directly attributable to thrombectomy, although two patients had cerebral embolization during the procedure. For prevention of this complication, we propose that both the aorta and the left atrium be explored during thrombectomy of either the mitral or the aortic prosthesis so as to achieve complete exposure of the left ventricular outflow tract and complete removal of any thrombus located in the ventricle. We consider this the procedure of tract and complete removal of any thrombus located in the ventricle. We consider this the procedure of choice in thrombosis of the Björk-Shiley prosthesis. Replacement of the prosthesis would then be restricted to cases of prosthesis damage or those in which adequate anticoagulation cannot be maintained.

Adult↗
PubMed1981

[Liquid storage media for vascular prosthesis of biological origins : their impact on biocompatibility (author's transl)].

Unlike synthetic arterial substitutes which are supplied as presterilized, dry-packaged products with potentially indefinite shelf lives, arterial prosthesis of modified biological origin must stored in less convenient liquid preservative media. These preservatives can affect the post-implantation performance and the biocompatibility of the devices. In order to identify the most suitable media, a modified "in vitro" cell culture test method was developed. It makes use of endothelial cells prepared from the aorta of chick embryo. In general, the prosthesis stored in liquid media had a disappointing performance from the point of view of neo-endothelium development and adhesion. Residual cytotoxicity was also noted for most of these currently used prosthesis storage and pre-surgical preparation protocols. Although devices stored in physiologic media showed adequate biocompatibility according to this cell culture test, it appears that neo endothelialization does not proceed concurrently with healing. Cellular development where present, adheres poorly to the substrate and cannot resist the shear forces of normal blood flow. Pre-implantation treatment of such prosthesis with cellular growth-promoting substances may enhance cell-prosthesis adhesion.

Animals↗
PubMed1980

Long-term follow-up of patients who underwent single valve replacement with Björk-Shiley prosthesis.

Single heart-valve replacement with a Björk-Shiley prosthesis was undertaken in 118 patients between Jan. 3, 1970 and Dec. 31, 1977. The hospital mortality was 7% for patients who had aortic valve replacement and 9% for those who had mitral valve replacement. Recent improvements in techniques for myocardial preservation and cardiopulmonary bypass resulted in a notable reduction in hospital mortality during the period 1974 to 1977 compared with that in the period 1970 to 1973; the rate was 5% for aortic valve replacement and 4% for mitral valve replacement between 1974 and 1977 compared with 9% and 18%, respectively, during the period 1970 to 1973. There was an additional late mortality of 8% in patients who had an aortic valve replaced and 11% in those who had a mitral valve replaced; the mean follow-up was 2.3 years (range 6 months to 7.5 years). Seventy-one patients with an aortic valve prosthesis and 38 patients with a mitral valve prosthesis were alive at the time of late follow-up. In patients who received an aortic valve prosthesis, 73% had an excellent result after operation (New York Heart Association classes I or II) and 18% had some functional improvement. In patients who received a mitral valve prosthesis, 68% had an excellent result and 18% were functionally improved after operation. The incidence of thromboembolism was 8.3% and of anticoagulant-related complications, 13.8%.

Adult↗
PubMedDate not supplied

Finite element analysis of a new system (IL) for supporting an implant-retained cantilever prosthesis.

A new system (the IL system) for supporting the distal extension of a cantilevered prosthesis is designed from a short implant and a special ball-type attachment. The finite element method was employed to analyze this system and the surrounding bone, as well as a conventional prosthesis, in two dimensions. Effective and maximum stresses in tension and compression were determined. A comparison of these quantities between the IL-supported prosthesis and a conventional prosthesis was carried out. It was observed that use of this system to support the distal extension of a cantilevered prosthesis dramatically lowers the stresses in the bone, cantilever, and implants. Therefore, this system may reduce failures within the implants, prostheses, and surrounding bone. Moreover, employment of a relatively long-span prosthetic extension in the posterior region of the jaw should be possible. This new system is recommended for completely and partially edentulous patients.

Dental Implants↗
PubMedDate not supplied

A new tracheal prosthesis made from collagen grafted mesh.

The authors studied the efficacy of a new tracheal prosthesis made from mesh. The prosthesis, 50 mm long and 18-22 mm in diameter, is made from a Marlex mesh cylinder reinforced with a continuous polypropylene spiral that is grafted and coated with porcine collagen to increase its biocompatibility and provide an airtight seal during the initial implantation stage. Circumferential surgical resection and replacement of a seven to nine ring segment of the cervical trachea was performed in 20 adult mongrel dogs. At the time of surgery, a silicone tube was inserted into the tracheal prosthetic lumen to promote secretory transportation until the prosthesis was covered with host tissue. The silicone tube was removed during fiber bronchoscopy 1 month after surgery. With the exception of the prostheses in 3 dogs that died of unrelated causes, all were infiltrated by connective tissue and incorporated completely by the host. One of these 17 dogs died of suffocation caused by luminal stenosis 2.5 months after surgery, but the others survived until they were killed at more than 6 months. The luminal surfaces of the reconstructed tracheae were covered with respiratory epithelium to varying degrees, and in one dog killed at 22 months after surgery, confluent epithelization throughout the length of the prosthesis was confirmed histologically. In eight dogs, prosthetic luminal stenosis occurred because of overgrowth of granulation tissue, which generally was mild in all but three dogs. The authors conclude that this tracheal prosthesis is highly biocompatible and shows promise for clinical application.

Anastomosis, Surgical↗
PubMed1996

[Guépar's total radio-carpal prosthesis in the surgery of the rheumatoid wrist. Apropos of 72 cases reviewed].

PURPOSE OF THE STUDY: Total wrist arthroplasty is an alternative to arthrodesis in the treatment of the rheumatoid wrist. MATERIAL AND METHODS: Seventy-two GUEPAR total wrist arthroplasties in sixty-four patients with rheumatoid arthritis were reviewed 1 to 10 years after the operation (average follow-up of 4 years). GUEPAR total wrist arthroplasty is a bicondylar prosthesis. The radial component made of polyethylene is cemented in the radius. The carpal component made of metal is fixed by two screws in the second and the third metacarpal. This component is constitued by two pieces: a perforated lower part permitting the passage of the screws and its metacarpal fixation and a biconvex cover fixed on the lower part by a micro-screw. RESULTS: In preoperative evaluation, all patients had severe pain and loss of function. Post-operatively, 89 per cent had no pain or mild pain and 96 per cent had better function. The average arc of flexion-extension was 47 degrees preoperatively and 39 degrees postoperatively. There were no deep infections or dislocations. Seventy percent of the patients were satisfied but eleven wrists (15 per cent) required revision: 5 cases for prosthesis revision and 6 cases for implant removal and arthrodesis. Prosthesis revisions were justified by the unscrewing of the carpal component micro-screw: they gived good results. Arthrodesis was required for 4 radial component loosening and for 2 important bone resorptions under the carpal component. Radial component loosening was associated in 3 cases with unscrewing of the micro-screw. Radiographical analysis showed in nearly all cases of this serie a bone resorption under the carpal component. This resorption was 2 mm wide at an average of to 2 years and 4 mm wide at 4 years. DISCUSSION: Clinical results of this study are good but eleven wrists required revision. Nine of these revisions were due to anomalies of first prosthesis: the unscrewing of the carpal component micro-screw was accountable to abnormal use of polyethylene with reaction of the wear products and loosening of the radial component. This problem is now resolved. More disquieting is the bone resorption under the carpal component. In fact, this resorption was constant and evolutive. It was very likely due to micro-movements between the metacarpal screws and the carpal lower part. Also, the conception of the metacarpal-fixation of this prosthesis must be revised. CONCLUSION: In rheumatoid arthritis, wrist arthrodesis gives good results if nothings affects the fingers, elbow or shoulder. If they are affected, total wrist arthroplasty is an alternative. Long term loosening of total wrist arthroplasty is a significant problem so its indication must be reserved for old patients.

Adult↗
PubMed1995

An above-knee prosthesis with a system of energy recovery: a technical note.

Knee flexion to 24 degrees during early stance transforms kinetic energy into potential energy of a total center of mass (TCM) position. Flexion is controlled by the musculoligamentous apparatus. Reproduction of such flexion in a new single-axis prosthesis knee unit has minimized the metabolic energy cost to the patient by a more favorable use of gravity acting upon the prosthetic segments and the body as well as of inertia. Potential energy is stored in the spring shock absorber of the knee unit. The coefficient of energy recovery increased by 30% in comparison with a conventional above-knee prosthesis. Energy costs to the patient decrease an average of 35% during gait with the new prosthesis. The same amount of unloading during walking is typical of an intact limb. The knee unit mechanism has a link set on the axle, thus providing two joints with a common axis: a) the main joint for knee flexion to 70 degrees during swing phase and flexion to 135 degrees during sitting; b) the second joint for bending at the beginning of stance phase. Compared with conventional units, gait with the new unit displays several functional advantages: 1) normal knee kinematics with movement of a TCM along a trajectory that contributes to an easy rollover of the foot and smooth and continuous translation of the body; 2) shock absorption during early stance prevents impact from the anterior brim of the socket; 3) at mid-stance, the increase of the TCM position accumulates potential energy that results in a significant increase of the push-off force; 4) during rapid gait, the unit provides adequate resistance to knee flexion; 5) location of the joint axis in front of the line of gravity loads the prosthesis in standing, making possible unimpeded carrying of the prosthesis over the support, the lengths of the prosthetic and the intact limb being equal; in addition, it facilitates flexion before the beginning of the swing phase. Production of the units began in 1992.

Amputation Stumps↗
PubMed2006

Assessment of hemodynamics properties of a new-type artificial heart valve prosthesis using catheterization and echocardiography.

OBJECTIVE: The objectives of this study were to assess the hemodynamic properties of the newly developed artificial heart valve prosthesis experimentally in laboratory simulation, in an animal model, and clinically in a human model and to compare the results measured by catheterization and echocardiography. METHODS: (1) Laboratory simulation. The prosthesis was tested using a pulsatile flow simulator in the aortic position. Hydrodynamics parameters were automatically analyzed through a custom-designed data processing program. (2) Animal experiment. Six sheep subjected to mitral replacement with 21-mm-valve prosthesis were measured by open cardiac catheterization intraoperatively. Doppler echocardiography and open cardiac catheterization under dobutamine stress were performed in two sheep subjected to implantation 2.5 years ago. (3) Clinical patient observation. Observations were carried out on 14 patients with aortas replacement and 10 patients with bicuspid replacement using both doppler echocardiography and open cardiac catheterization. RESULTS: (1) Laboratory simulation. The results showed that the value of the transvalvular gradient (DeltaP) decreased with the increase of heart rate, and the values were not greater that 10 mm Hg at any given tissue annulus diameter. (2) Animal experiment. The mean DeltaP value of the six sheep was 5.2 +/- 1.7 mm Hg intraoperatively, while the corresponding DeltaP value of the two sheep 2.5 years after implantation was 6.1 +/- 0.3 mm Hg measured by open cardiac catheterization. (3) Clinical patient observation. The mean DeltaP values in the aortic position measured by catheterization and echocardiography were 6.26 approximately 4.10 and 9.42 approximately 7.48 mm Hg, respectively. The gradients in the mitral position were 2.10 approximately 1.9 and 5.28 approximately 4.10 mm Hg, respectively. CONCLUSIONS: The results demonstrate that the new-type bileaflet heart valve prosthesis only generates a relatively low transvalvar gradient and thus has good hemodynamic properties.

Adult↗
PubMed2001

An individualized approach for the implantation of a humeral prosthesis with the proper retroversion in fractures.

We applied a new methodology in 7 patients with a fracture of the upper humeral head that required hemiarthroplasty, to implant a humeral prosthesis with an individualized posterior version. Our goal was to determine preoperatively the distance from the posterior edge of the bicipital groove where the lateral fin of the humeral prosthesis should sit, in order to reproduce the individual retroversion during surgery. Using three computed tomography scan sections of the upper humerus and image processing software, we estimated the above-mentioned distance in the sound humerus and implanted the prosthesis in each patient accordingly. The differences in retroversion between the left and right humeral heads permit a better approximation to normal applying this methodology than inserting the prosthesis in a standard retroversion.

Humans↗
PubMed2006

Numerical model study of flow dynamics through an end-to-side anastomosis: choice of anastomosis angle and prosthesis diameter.

The purpose of this numerical model study was to determine the angle of anastomosis and prosthesis-to-artery diameter ratio that theoretically limits development of myointimal hyperplasia (MIH). Blood flow patterns were investigated in a model simulating a distal end-to-side anastomosis on a 2-mm-diameter artery. Tests were carried out under steady and pulsatile flow conditions with and without taking into account the non-Newtonian behavior of blood and compliance. The wall shear stress gradient (WSSG), a potential factor for development of MIH, was analyzed as a function of the angle of anastomosis (18 degrees , 25 degrees , 35 degrees , and 45 degrees ) and prosthesis diameter (4, 5, and 6 mm). The angle of anastomosis that minimized WSSG was 18 degrees . Prosthesis diameter had no effect on WSSG, with similar results for all three diameters. These findings suggest that surgeons should choose as acute an angle of anastomosis as possible. Prosthesis diameter played no role in reducing WSSG values.

Anastomosis, Surgical↗
PubMed2000

Current status of penile prosthesis implantation.

Today most men with erectile dysfunction (ED) can be effectively treated with less invasive means than penile prosthesis implantation. Nevertheless, there remain men who do not respond to simple treatments such as systemic medication and who either do not respond to or reject intermediate treatment such as penile injection therapy. For these men, penile prosthesis implantation remains a reasonable option. This review discusses types of penile prostheses, how to choose among prosthesis types, key features of implant techniques, infection management, penile reconstruction related to prosthesis implantation, and patient and partner satisfaction.

Erectile Dysfunction↗
PubMed1994

Intraatrial insertion of a mitral prosthesis in a destroyed or calcified mitral annulus.

Infectious lesions and extreme calcification of the mitral valve annulus can make classic anatomic implantation of a prosthesis impossible. Confronted with these circumstances, we have developed a technique of intraatrial insertion of a mitral prosthesis. The prosthesis has been modified by enlarging the circumference of the sewing ring with a Dacron collar. The collar can be sutured to the left atrial wall above the mitral annulus. From 1981 to 1989, this technique has been employed in 36 patients: 15 had acute valve endocarditis with destruction of the mitral annulus and 21 had extensive annular calcification. In all cases, circumferential or partial intraatrial insertion permitted a secure implantation of the prosthesis. One operative death was related to the technique. It was an intractable bleeding caused by tearing of the very thin and fragile wall of the left atrium in a kidney transplant patient. Four patients were reoperated on for periprosthetic leak, in 3 of whom healing and cleaning of the mitral annulus permitted annular implantation of a prosthetic valve. There was no ventricular wall rupture. Our results suggest that the technique can be performed in high operative risk patients when mitral valve replacement is impossible by conventional techniques.

Calcinosis↗
PubMed1990

Experience with Duraphase penile prosthesis: its use as replacement device.

The Duraphase Penile Prosthesis is a new, articulating type of semirigid prosthesis which appears to have several advantages over other semirigid penile prostheses. This series describes the experience with this prosthesis in 12 patients and highlights the experience in 4 patients who underwent removal of other types of prostheses due to mechanical or functional problems and replacement with the Duraphase prosthesis. The device has been mechanically reliable during short follow-up, and there has been excellent patient satisfaction.

Aged↗