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At least 361 records · Page 20Linked to original sources
PubMed1999

Video-assisted replacement or bypass grafting of the descending thoracic aorta with a new sutureless vascular prosthesis: an experimental study.

PURPOSE: The feasibility of the video-assisted insertion of a new sutureless vascular prosthesis was studied. METHODS: Seven sheep, weighing 25 to 35 kg, were operated on under general anesthesia. The animals were intubated with a single-lumen endotracheal tube and placed in the right lateral decubitus position. A thoracoscope was introduced in the 11th intercostal space, and a minithoracotomy (4 to 5 cm) was performed in the seventh intercostal space. After retraction of the lung, a short segment (10 cm) of the descending thoracic aorta was exposed. Our prosthesis was made of Dacron and was specifically designed to be inserted without a suture. After systemic heparinization, the aorta was cross-clamped with two vascular clamps introduced into the thoracic cavity through two 5-mm thoracic incisions. The aorta was either replaced (five cases) or bypass grafted (two cases). At the completion of the procedure, blood pressure was pharmacologically increased (5 mg intravenous bolus of epinephrine), and each anastomosis was checked for bleeding. All animals were killed, and the prosthesis was retrieved for macroscopic examination. RESULTS: The procedure was completed in each case without extension of the minithoracotomy. Insertion of the prosthesis was easy and fast, and completion of each anastomosis required 10 to 15 minutes. A 3- to 4-mm space between each clip was sufficient for proper attachment. All procedures were performed in less than 120 minutes. No bleeding was observed at the level of each anastomosis, even when a sustained high blood pressure was induced. The proper insertion of the prosthesis and the absence of any anastomotic stenosis was confirmed by means of macroscopic examination. CONCLUSION: Video-thoracoscopic replacement or bypass grafting of the descending thoracic aorta was easy with this new sutureless vascular prosthesis. Minimally invasive vascular surgery might be facilitated with such a prosthesis. However, long-term animal studies are required before human implantation can be undertaken.

Animals↗
PubMedDate not supplied

[The hollow prosthesis. Reflections on cementless hip endoprosthesis anchorage].

Hollow prostheses appear to represent a promising approach for the durable fixation of cementless hip-joint endoprostheses. The goal of the planned development is the design-engineering, quality-assured production and clinical testing of hollow prostheses displaying largest possible interior space and optimized wall thickness. With hollow prostheses the possibility exists for the first time of filling both the interior space of the prosthesis and cavities between the prosthesis bearing and the prosthesis with spongiosa. Theoretical considerations indicate that this should result in early and durable secondary stability. First results from animal experiments show that the canine femora operated on display a stress distribution closely approximating the natural stress distribution in the bone and exhibit the expected ingrowth of spongiosa into the interior space of the hollow prosthesis. The choice of suitable materials and particularly of wall thickness and cross-sectional shape has a decisive bearing on the elastic behaviour of the prosthesis. Compared with a solid prosthesis of the same geometry, a hollow prosthesis exhibits reduced flexural rigidity and hence higher elasticity. The dynamic tests performed on hollow prostheses in line with DIN 58,840 have shown that--given careful design and manufacture as well as effective quality-assurance measures--fatigue failure is not to be expected in the case of hollow prostheses.

Animals↗
PubMed2002

Implantation of hemipelvic prosthesis after resection of sarcoma.

Twelve adult patients with pelvic sarcoma had implantation of a hemipelvic prosthesis. Eight patients had hemipelvic resection, and four patients had acetabulopubic resection. The implanted prosthesis was a special Vitallium prosthesis, which was specially designed for each patient with the aid of a computer. At a median followup of 57 months, eight patients were free of disease. In four patients with local relapse, two had additional resection, one had hindquarter amputation, and one was observed. In three patients with deep infection, the prosthesis was removed; however, one patient had hindquarter amputation. One patient had dislocation of the hip and prosthesis loosening. Overall survival of patients was 70%, and the survival of prostheses was 42%. In eight patients, the functional evaluation showed that the average functional score with the prosthesis was 11.6 (39%) and without the prosthesis the functional score was 7.0 (23%). Implantation of a megaprosthesis seems to indicate a high complication rate and a poor functional result after hemipelvic resection.

Adult↗
PubMed2000

Clinical and finite element analysis of a modular femoral prosthesis consisting of a head and stem component in the treatment of pertrochanteric fractures.

OBJECTIVE: To determine the biomechanical characteristics and potential clinical efficacy of a cementless modular femoral prosthesis consisting of a variable head (50 to 80 millimeters) and stem (length 120 to 280 millimeters, diameter 10 to 20 millimeters) component in patients with pertrochanteric femoral fracture. DESIGN: Finite element analysis (FEA) of different lengths and diameters of prosthesis components and first clinical prospective study in pertrochanteric femoral fracture. METHOD: Using a 3D-CAD program, a model of femoral cortical bone with a pertrochanteric fracture was created and combined with a model of the prosthesis. This model was transferred into an FEA program. After applying a torsion-bending load of 2,000 N (25 degrees, 45 degrees) on the prosthesis, stress distribution in the cortical bone was determined for different lengths (160 to 240 millimeters) and diameters (10 and 12 millimeters) of stem. PATIENTS: Twenty-eight patients with pertrochanteric fractures (very unstable or osteoarthritis) were treated with a modular hip arthroplasty. Complications, fracture healing, and results at first follow-up (average 13 months) were determined. RESULTS: FEA analysis indicated that reduction in stress was less when a prosthesis with a short stem was used. Shear stress in the interface bone/prosthesis was not affected by stem length. Prostheses with thin stems produced higher sheer stresses than those with thick stems. Results of FEA were used as the basis for clinical application of the device. None of the patients died, and all patients were able to walk, although some needed a cane or walker after surgery. There was no increase in thigh pain compared with reported pretrauma levels. Radiographs showed subsidence of up to 5 millimeters in 20 percent of patients. However, all but one prosthesis was stable at follow-up. Fracture healing was achieved in all patients. CONCLUSIONS: If proximal fixation of a femoral uncemented stem cannot be achieved, stem diameter should provide maximum cortical contact to reduce sheer stress. Longer stems do not necessarily provide additional stability. By using this prosthesis and selection method, a good outcome at first follow-up was observed.

Activities of Daily Living↗
PubMed1987

[Revision prosthesis for the hip joint in severe bone loss].

When total hip prostheses loosen after initial implantation and subsequent prosthesis replacement, increasing bone resorption occurs in the bed of the prosthesis. Finally, a very thin cortex remains in the bed of the prosthesis, which no longer provides sufficient mechanical stability. The replacement prosthesis described, which is anchored in the distal medullary canal without cement, provides a bridge over the damaged prosthesis bed and results in a condition of relative mechanical stability. After implantation of the replacement prosthesis, lively proliferation of the bone tissue occurs in the old prosthesis bed, which again replaces the bone loss that had taken place previously. The late results that would permit a final assessment of the procedure are not yet available.

Bone Regeneration↗
PubMed1996

Cellular basis for failure of joint prosthesis.

In recent times, loosening of joint prosthesis resulting in failure, is of grave concern to orthopedicians. It is estimated that 50% of total hip replacements become loose after 15 years, and most of them require either revision surgery or resection orthoplasty. Neither, newer operative techniques, change in design, use of novel materials, nor surface modifications have helped to circumvent the problem. It is in this context, that attention has been focussed on the role of tissue surrounding the implant, in the loosening of the prosthesis. Tissue response around prosthesis results in either formation of a fibrous layer around the implant, ingrowth into fenestrations on implant or direct bone apposition on prosthesis. Long-term implantation results in implant debris being released into surrounding tissue. These particles initiate a chronic granulonatous inflammation with a significant number of activated macrophages and foreign body type of giant cells, all engaged in attempts to get rid of the debris. These features have been found to be invariably associated with peri-prosthetic lysis of bone. Since such bone resorption is also observed around non-cemented prosthesis, possibly causes other than cement are responsible for the osteolysis. Retrospective studies on failed implants suggest that peri-prosthetic osteolysis is mediated by activated macrophages. Cytokines are capable of stimulating bone resorbing cells, the osteoclasts. Bone resorption results in further loosening of the prosthesis, changes in stress, frictional wear, release of more wear debris and recruitment of more macrophages. Bone death and proliferation of macrophages, thus appear to be the cause for pain and loosening of prosthesis.

Biocompatible Materials↗
PubMed1990

[Voice rehabilitation following total laryngectomy: microvascular laryngeal replacement-plasty (laryngoplasty) instead of voice prosthesis].

Since the introduction of the so-called voice prostheses tracheoesophageal puncture is currently the most widely used surgical procedure for vocal rehabilitation after total laryngectomy. The voice prosthesis renders possible a reliably reproducible voice, which is superior (period of uninterrupted sound production, basal frequency, voice intensity) to the other techniques (esophageal speech, external vibrators, other surgical reconstructive measures), but has the following disadvantages: high initial phonation pressure, formation of granulation tissue around the voice shunt, blockage or leakage of the prosthesis or the voice shunt, displacement of the prosthesis, spontaneous occlusion when the prosthesis is accidentally removed, overtaxing the patients who have difficulties in replacing and cleaning the prosthesis. As an alternative new surgical technique a substitute larynx tube (laryngoplasty) was formed by a microvascular anastomotic forearm flap and connected to the trachea and pharynx in ten patients with extensive (T3-T4) laryngohypopharyngeal carcinoma. All ten patients developed a voice comparable with those of patients who have a voice prosthesis (frequency, voice intensity, period of uninterrupted sound production). An advantage of this graft over the voice prosthesis is that the phonation pressure required is low. While they were still in hospital eight patients learned to speak without using their hands by means of a tracheostomal valve. So far (six months postoperative) this surgical procedure has proved to be a practicable surgical alternative to a voice prosthesis.

Animals↗
PubMed2001

Labyrinthine fistula: an unreported complication of the Grote prosthesis.

OBJECTIVES: To alert the otological surgeon that labyrinthine fistula is a rare and avoidable complication of the Grote hydroxyapatite ceramic external auditory canal (EAC) prosthesis. The reasons for its causation and strategies to prevent its formation are discussed. STUDY DESIGN: Case study and retrospective review of the literature. METHODS: Labyrinthine fistula that occurred after the use of the Grote hydroxyapatite ceramic EAC prosthesis is presented. The literature is reviewed retrospectively for various methods of reconstruction of the EAC following canal wall down mastoidectomy. Strategies and principles are outlined to avoid complications associated with reconstruction of the mastoid and EAC. RESULTS: The Grote hydroxyapatite (HA) prosthesis is a reliable prosthesis for reconstruction of the external auditory canal (EAC) in the absence of a draining mastoid cavity or cholesteatoma and with adequate soft tissue cover. Contact of the medial end of the prosthesis with the lateral semicircular canal must be avoided. Immobilization or rigid fixation and avoidance of infection are essential for optimal prosthesis stability and osseointegration. Covering the prosthesis with vascularized soft tissue appears to be important for the achievement of a successful reconstruction. CONCLUSION: The Grote prosthesis is safe and effective provided it does not contact the lateral semicircular canal, is stabilized, and covered by vesicular tissue, in the absence of infection.

Durapatite↗
PubMed2000

Effects of titanium prosthesis, offset and size of field of view on bone mineral density measurements using quantitative computed tomography.

To estimate the accuracy of quantitative computed tomography (QCT) as a method to measure bone mineral density (BMD) in the vicinity of a titanium prosthesis, we investigated the effects of (1) titanium prosthesis, (2) offset of the longitudinal axis of the bone to be examined from that of the gantry of the CT scanner, (3) size of the field of view (FOV) and (4) the combination of these effects on CT based measurements of mineral density of cortical and cancellous bone specimens. 14 bovine cortical bone parallelepipeds and 14 bovine cancellous bone parallelepipeds were used in this investigation. The bone specimens were scanned with and without a titanium prosthesis, when centered in the gantry of the CT scanner and offset from the axis of the gantry of the CT scanner at a distance of 14 cm. Image data were then reconstructed separately with a FOV of 10 cm and 30 cm. All BMD values taken from CT images obtained under different scanning condition were compared with the BMD values of the corresponding bone parallelepiped obtained under standard condition (centered in the gantry of the CT scanner, 10 cm FOV, without titanium prosthesis). When centered in the gantry of the CT scanner, the mean relative difference of BMD measurements caused by the presence of the titanium prosthesis was less than 1% for both cortical bone and cancellous bone. Size of the FOV had a negligible effect on BMD measurements. Offset at 14 cm, however, caused a significant difference in BMD measurements (p < 0.001). It was concluded that titanium prosthesis did not interfere with BMD measurements of cortical and cancellous bone when both the specimen and prosthesis were centered in the gantry of the CT scanner. However, the effect on BMD measurements of offset at 14 cm combined with the presence of a titanium prosthesis in bone was significant.

Animals↗
PubMed2002

[The histological study of the capsules formed around the mammary prosthesis].

OBJECTIVE: To observe and analyze the pathohistological characteristics of capsules which formed around the mammary prosthesis with different contents. And to provide the selective basis for ideal and safe prosthesis in clinical practice. METHODS: 20 specimen of the capsules were taken from 20 cases who receive the operation of prothesis removal for different reasons. HE, Masson and Mallory staining were used to analyse the tissue structure and characteristics under the light microscope. RESULTS: The common structure including the collagen fibers accumulation, inflammatory cells infiltration and the capillary hyperplasia were found in all specimen. A layer of squamous epithelium-like cell was detected in some specimen. The specific characteristics were also found in different capsules formed around different prosthesis. In the capsules around vegetable oil prosthesis, there was excessive collagen fiber accumulation, and the capsules were much thicker. In the PVP (polyvinylpyrolidone) prosthesis capsules, there was severe inflammatory cell infiltration, and the number of eosinophilic granulocyte increased obviously. In the silicone gel and saline prosthesis capsule, the collagen fibers were well-arranged and the inflammatory cells were much less. Synovial metaplasia was detected in two cases. CONCLUSION: 1. The capsules form around the prosthesis in all cases after mammary augmentation. 2. There will be synovial metaplasis in some cases, for vegetable oil prosthesis, the collagen over-accumulated which lead the capsules become thicker and harder. So it is not a kind of ideal mammary prothesis. 4. The severe infiltration of the inflammatory cells especially the large quantity of eosinophilic granulocyte indicate the possibility of the delayed hypersensitive reaction mediated by eosinophilic granulocyte. Cautious attitude should be taken during application.

Adult↗
PubMedDate not supplied

[Our experience with the use of a plastic prosthesis and self-expanding stents in the palliative treatment of malignant neoplastic stenoses of the esophagus and cardia. Comparative analysis of results].

Rapid palliation of malignant dysphagia is usually possible by means of the endoscopic implantation of a plastic prosthesis, but this device has a high morbidity rate. Recently, expandable metal stents have become available and may reduce the morbidity and mortality rates. The aim of this retrospective study was to evaluate self-expanding metal stents compared with conventional plastic prosthesis in malignant strictures of the oesophagus and cardia. One hundred and thirteen endoscopic tube implantations were carried out in 120 patients with malignant stenosis of the oesophagus and cardia using a plastic prosthesis over the period 1980-1993 (72 cases) and self-expanding metal stents over the period 1993-2001 (48 cases). The underlying causes of strictures were oesophageal or cardial cancer in 108 cases and oesophageal invasion by lung cancer in 12. The indications for endoscopic intubation were advanced tumour stage and/or risk factors which made resection inadvisable. The stents used in the conventional group were the Celestin pulsion tube in 18, the Atkinson prosthesis in 23 and the Wilson-Cook tube in 27, while the Ultraflex stent was always employed in the other group. Dysphagia was scored according to the Atkinson and Ferguson classification and the preoperative median score (3.6) was comparable in the two groups. The technical success rate was 94.4% with the plastic prosthesis (68/72) and 93.7% with the self-expanding metal stents (45/48) because in 4 and 3 patients, respectively, it proved impossible to implant the stent. After intubation the dysphagia score was improved in both groups (median score = 0.9) and the functional success rates were 85.2% (58/68) and 88.8% (40/45), respectively, while 10 and 5 patients showed no improvement of symptoms. The early complication rate was 5.9% (4/68) in the conventional stent group (1 perforation, 2 severe bleedings and 1 stent proximal migration) and nil in the other group. Late complications occurred in 14 (20.6%) (7 food obstruction, 4 neoplastic obstructions and 3 dislodgements) and 9 patients (20%) (3 neoplastic obstructions, 1 food obstruction, 3 distal migrations and 2 bleedings), respectively, but all the complications were easily corrected. Three deaths occurred with the plastic prosthesis (4.4%), while the mortality was nil with the metal stents. The median survival times were 183 (range: 58-486) and 151 days (range; 25-545), respectively. Our experience suggests that endoscopic placement of self-expanding metal stents is effective and safe for the management of dysphagia in malignant strictures of the oesophagus and cardia and has to be preferred to conventional plastic prostheses for easier implantation. The technical and functional success rates are similar in both groups, but the acute complication and mortality rates of the Ultraflex prosthesis are lower as compared to the traditional prosthesis.

Adult↗
PubMed1985

Complications from a testicular prosthesis in a stallion.

A testicular prosthesis was removed from the scrotum of a 3-year-old Quarter Horse stallion. The prosthesis had been placed in the left side of the scrotum 10 months earlier, after an unsuccessful attempt to reposition the retained left testis. Because of a persistent draining fistula on the scrotum, first noted 5 months after placement of the prosthesis, surgery was performed to remove the prosthesis. At surgery, the left testis was found in a fibrous mass surrounding the prosthesis. The left testis had descended after placement of the prosthesis, and its involvement in the fibrous tissue surrounding the infected prosthesis necessitated its removal. Had the prosthesis not been placed, descent of the left testis probably would have resulted in an essentially normal stallion.

Animals↗
PubMed1993

The Angelchik prosthesis behaves as a fundoplication.

It is not known why the Angelchik prosthesis prevents gastro-oesophageal reflux. A review of 53 barium meal examinations in 39 patients with the prosthesis showed that in 43 examinations the prosthesis was below the diaphragm. In 38 of these a small knuckle of stomach had herniated through the prosthetic ring alongside the oesophagus, forming a small intra-abdominal para-oesophageal hernia. Radiological reflux occurred in only one patient with such a hernia. In the remaining five examinations where the prosthesis was correctly situated in the abdomen, there was no hernia within the prosthetic ring and reflux occurred in three. In ten examinations the prosthesis had migrated into the mediastinum. None of these showed a hernia and reflux occurred in eight. It is suggested that the Angelchik prosthesis results in the formation of a small para-oesophageal hernia within a loosely fitting ring within the abdomen and this is a requirement for the success of the Angelchik prosthesis. Radiographically the intra-abdominal para-oesophageal hernia inside the prosthesis results in buttressing of the intra-abdominal oesophagus in a manner similar to a fundoplication.

Barium Sulfate↗
PubMed2006

Voice rehabilitation with Provox2 voice prosthesis following total laryngectomy for laryngeal and hypopharyngeal carcinoma.

OBJECTIVE: To analyze the effectiveness of the Provox2 voice prosthesis for voice rehabilitation following total laryngectomy. METHODS: From September 2000 to December 2004, the Provox2 voice prosthesis was used for voice rehabilitation in 32 patients following total laryngectomy. The quality of speech with the Provox2 voice prosthesis was analyzed using the HRS rating scale, the maximum phonation time (MPT), incidence of complications and the in situ lifetime. The rate of speech restoration was further analyzed in 129 patients with total laryngectomy from 1996 to 2004. RESULT: Twenty-nine of 32 patients were able to restore speech using the Provox2 voice prosthesis, a speech restoration rate of 90.6%. The maximum phonation time (MPT) was measured in 18 patients using the Provox2 voice prosthesis. The mean MPT was 15.1 s, with a range of 8-28 s. MPT was not influenced by age, concurrent radiotherapy treatment, the location of the primary tumor or use of reconstructive surgery. The average lifetime of the Provox2 in patients with laryngeal carcinoma (12 patients) and hypopharyngeal carcinoma (17 patients) was 27.2 and 16.6 weeks, respectively, which was significantly different (P=0.024, non-parametric Mann-Whitney's U-test). The rate of speech restoration by the use of esophageal speech, and insertion of an artificial larynx was 62.7% for laryngeal carcinoma (59 cases) and 38.6% for hypopharyngeal carcinoma (70 cases), which was also significantly different (P<0.01, chi-square test). CONCLUSION: Provox2 voice prosthesis speech was very useful due to the higher rate of speech restoration, longer phonatory time, and better intelligibility. It was also thought that voice prosthesis speech was useful in conjunction with esophageal speech and an artificial larynx depending on the patient's condition or wishes.

Aged↗
PubMed1985

Hemodynamic evaluation of the integral monostrut Björk-Shiley prosthesis in the aortic position.

Between May, 1983, and November, 1984, the new integral monostrut Björk-Shiley prosthesis was used for aortic valve replacement in 62 patients. The prosthesis is machined from a solid piece of cobalt alloy and has no welded joints. The traditional U-shaped outlet strut has been replaced by a projecting metal finger that holds the disc in place. The disc opens to 70 degrees and is convexoconcave. Successful transseptal heart catheterization was performed in 23 patients an average of 6 months following operation to evaluate the hemodynamic performance of the prosthesis. The mean peak-to-peak gradient was 7.73 +/- 7.49 mm Hg (+/- standard deviation). In five valves it was 0, and in only three was it higher than 15 mm Hg. Significant peak gradients were directly related to the valve index (valve area/body surface area). Mean systolic gradient at rest was 12.7 +/- 6.27 mm Hg and did not increase after exercise. Effective orifice areas were adequate, and the discharge coefficient ranged from 0.77 for the 21-mm prosthesis to 0.48 for the 29-mm prosthesis. Minimal regurgitation, which was washed out on the next systole, was observed with all sizes of the prosthesis. Disc opening was maximal (70 degrees) in all but one of the observed instances. Longer clinical follow-up is required, but the new integral monostrut Björk-Shiley prosthesis, with its important design changes and excellent hemodynamic performance, appears to be a promising aortic valve substitute.

Adult↗
PubMed2004

[The Bryan cervical disc prosthesis. Preliminary clinical experience with nine implants].

PURPOSE: After an anterior cervical discectomy, immobility at the fused level may increase stress on adjacent disc spaces and causes disc degeneration in 92% of the cases with clinical manifestations in 25.6% of the patients within 10 years. The cervical disk prosthesis may help to prevent this problem. The Bryan prosthesis (Medtronic Sofamor Danek) is currently available in France after a European pilot study. METHODS: Since January 2002, 8 patients (9 implants) (mean age: 35 years) were operated on with a prosthesis implantation for disc degeneration after an adjacent previous interbody fusion in 2 patients and for disc herniation or spondylosis in 6 patients. The prosthesis were implanted at the C4-C5 level (one patient), C5-C6 (four patients), and C6-C7 (four patients). Post-operative radiological evaluations with dynamic X-rays and clinical status (Odom questionnaire) were analyzed. RESULTS: Surgical procedures, which were longer than the classical technique, were uneventful. Radicular pain resolved after surgery with excellent results with the Odom's score. With a mean follow-up of 12 months, the prosthesis mobility was 8.9 degrees . But one fusion of an implant was encountered 6 months after implantation. CONCLUSIONS: The general follow-up for the Bryan(R) cervical disc prosthesis implantation is still too short (2 years) for a definitive evaluation. If clinical results on pain are as good as expected, long-term mobility of the prosthesis has to be checked, as it is the main advantage over classical anterior cervical discectomy with fusion. Patient selection has to be considered.

Adult↗
PubMed2003

Finite element analysis of the cervico-trochanteric stemless femoral prosthesis.

OBJECTIVE: To investigate the biomechanical performance of a newly designed cervico-trochanteric stemless prosthesis by comparing the stress distribution with that of the traditional stem-type porous-coated anatomic prosthesis. DESIGN: Three-dimensional finite element models were created for the intact femur, cervico-trochanteric implanted femur and porous-coated anatomic implanted femur. The stress distributions on the femur and the implant were compared. The effects of using two or three screws fixation for the cervico-trochanteric implanted femur were also investigated. BACKGROUND: Local bone loss after implantation of traditional stem-type prostheses remains an unsolved problem during the long-term application of total hip replacement. The stress shielding effect and osteolysis were thought to be the two main factors that result in local bone loss after prosthesis implantation. In order to eliminate the mechanical and the biological causes of bone loss after total hip arthroplasty, a newly designed stemless femoral prosthesis was investigated. METHODS: Three-dimensional finite element models were created for the intact, cervico-trochanteric (with two or three fixation screws), and porous-coated anatomic implanted femora with the geometry of a standardized composite femur. Analysis was performed for a loading condition simulating the single-legged stance. The von Mises stress distributions of each model were analyzed and compared. RESULTS: The results can be summarized as follows: (1) Von Mises stress in the proximal, medial femur for the cervico-trochanteric implanted model was higher than that of the intact model and the porous-coated anatomic implanted model; (2) stress-shielding effect of the cervico-trochanteric models (with two or three fixation screws) were eliminated as compared with the porous-coated anatomic model; (3) no obvious difference in von Mises stress distribution for the cervico-trochanteric implanted model with two or three fixation screws. CONCLUSIONS: The cervico-trochanteric femoral prosthesis may reduce the stress-shielding effect of the proximal femur and achieve a more physiological stress distribution on the proximal femur than that of the porous-coated anatomic prosthesis. RELEVANCE: The new concept of cervico-trochanteric stemless prosthesis has proven to possess several advantages based on the current results, and may be an alternative for traditional stem-type prostheses in future clinical applications.

Biomechanical Phenomena↗
PubMed1996

Expandable prosthesis for sutureless anastomosis in thoracic aorta prosthetic substitution.

OBJECTIVE: Most complications of descending aorta prosthetic substitution seem mainly to be related directly (ischemia to distal organs, i.e. liver, kidney, spinal cord) or indirectly (extracorporeal circulation or shunts and systemic heparinization complications) to the duration of blood flow interruption. the purpose of this study is to report the results of animal experimentation of a new device for sutureless prosthetic substitution of the descending thoracic aorta, with a very short cross-clamping phase. METHODS: The device consists of expandable loops of stainless steel wires, sewn to the proximal end of a Dacron prosthesis. The stainless steel wire loops can be expanded and tightened by activating a removable guide in such a way that the prosthesis varies its diameter, while maintaining a regular cylindrical shape. The device was prepared in two different configurations, one for long segments (expandable prosthesis end) and the other to be used for very short segments or as an anastomotic ring between prosthetic or vascular stumps (quick anastomotic ring). The expandable prosthesis end was tested in swine experiments by performing the prosthetic substitution of the first 10 cm of descending cross-clamped aorta, the prosthesis being fixed with the device both at the proximal and the distal ends (six experiments). All animals survived the procedure, that was accomplished with a very short cross-clamping time. The quick anastomotic ring was used to anastomose two prosthesis ends, at the middle of the prosthetic segment used for descending aorta substitution (two swine), to perform the distal anastomosis in the same model of descending aorta substitution (one swine) and simply to re-anastomose a subtotally transected descending aorta (one swine). RESULTS: The present experience proved the reliability of the device to carry out a sutureless, accurate, simple and quick anastomosis. Its advantage over an intraluminal ringed prosthesis is much easier insertion of the retracted wired end into the vascular stumps, thus allowing for a prosthetic diameter appropriate to the substituted vessel. CONCLUSIONS: The reduced cross-clamping feature of the device would suggest its use mainly in thoracic aorta prosthetic substitution for the prevention of ischemic damage to distal organs; it can also be used to advantage wherever an end-to-end vascular or prosthetic anastomosis is indicated, providing an accurate, stented anastomosis.

Anastomosis, Surgical↗