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At least 1,063 records · Page 59Linked to original sources

PubMed1986

Long-term follow-up of patients with geomedic prostheses.

Of 122 Geomedic arthroplasties performed, 85 were possible to follow up. The mean observation period was 58 months. The original position of the prosthesis was analyzed with respect to its effect on the clinical condition. A score system was used for this purpose. A normal alignment was obtained in 51%. No statistically significant correlation could be shown between a high radiographic score and a high clinical score. A resorption zone of 2mm or more, considered a sign of loosening, arose in 37% and a coexisting change of position in 12%. There is no difference in radiographic score between the prostheses which were judged as loose and the other prostheses. Twelve percent of the patients were reoperated because of loosening. The patients consider their condition to be very good or good in 93% of cases. Pain at rest and pain on weight bearing were totally absent in 87% and 72% of cases respectively.

Adult↗

PubMed1980

Cochlear prostheses in use: recent speech comprehension results.

Speech-comprehension tests were performed with several deaf volunteers who were equipped with different cochlear prostheses. These prostheses work with inductive transcutaneous signal transmission and contain a multi-channel scala tympani electrode or, in two cases, a disc electrode situated external to the cochlea in the round window niche. The external portable single-channel speech-processor/transmitter used is the same in all cases. The comprehension (stimulation only, no lip reading) of numbers between 1 and 99 on first contact with the stimulator and therefore without any training was around 38% showing that through well designed single-channel stimulation of the auditory nerve it is possible to generate hearing sensations sounding very much like nature hearing impressions. Some open speech comprehension was reached: Through the help of the stimulator, without lip reading, between 60 and 100% of sentences unknown to the completely deaf volunteer, spoken only a little more slowly than normal, are correctly understood. The percentage for isolated unknown words is 60%. Also an important improvement of word comprehension can be achieved through additional stimulation as compared to unaided lip reading. It appears that the most recent design of our cochlear prosthesis can already be regarded as a useful aid for the deaf.

Adult↗

PubMed1987

[Complications following heart valve replacement by mechanical and biologic prostheses].

From 1973 to 1985 2394 mechanical valve prostheses (MVP) (follow-up time 110,653 months) and 186 biological valve prostheses (BVP) (follow-up time 5887 months) were implanted. There were only small differences according to the cumulative incidence of prosthetic malfunctions, for reoperations after 10 years: MVP 5.4 +/- 0.4%; BVP 7.7 +/- 0.9%. The total reoperation incidence/100 patient-years was for MVP 1.14, for BVP 2.65. Further complications resulted from anticoagulation therapy (thrombemboli, bleeding), and prosthetic valve endocarditis. The cumulative freedom of any complications after 10 years was 73.1% for Björk-Shiley-AVR, 54.2% for BS-MVR, and only 31.2% for BS AVR + MVR. These results indicate regular controls for all patients postoperatively.

Bioprosthesis↗

PubMed1994

Kinematics of successful knee prostheses during weight-bearing: three-dimensional movements and positions of screw axes in the Tricon-M and Miller-Galante designs.

Using roentgen stereophotogrammetric analysis we recorded the three-dimensional movements in six knees with implanted Tricon-M prostheses and ten knees with Miller-Galante prostheses as the patients ascended a platform. Fourteen patients with normal knees were used as controls. The two prosthetic designs displayed decreased internal tibial rotation and the Tricon-M increased valgus rotation. A central point on the tibial articular surface had a more lateral position in the Tricon-M design and a more distal one in the Miller-Galante design compared to normal knees. Increased posterior displacement with increasing flexion was observed in both designs. When the normal knees were extended at full weight-bearing the helical axes mainly shifted inclination in the frontal plane. In the prosthetic knees there was a tendency to anterior-posterior displacement of the axes as extension proceeded, especially in the Miller-Galante design. Translations along the helical axes were larger than normal in the Miller-Galante and smaller in the Tricon-M knees, reflecting differences in constraint of the two designs.

Aged↗

PubMed1977

[The ultrastructure of the neointima of arterial prostheses made of lyophilized human dura. Long-term results in dogs (author's transl)].

Five arterial prostheses made of lyophilized human dura (LHD) were inserted into dogs and removed after 4, 5 1/2, 13, 43, and 46 months to be studied with the electron microscope. The neointima of all grafts consisted of pseudo-endothelial cells, fibrocytes, and collagen fibrils. Additionally, 43 and 46 months after implantation smooth muscle cells and elastic microfibrils were present. Thus, the composition of the neointima was substantially identical with that of the neointima of synthetic arterial grafts and collagen-fabric ones. The clinical application of arterial prostheses of LHD, however, seems at present too early because of degenerative changes in the walls of those grafts which remained nearly 4 years in the dogs.

Animals↗

PubMed2002

Kinematic analysis of mobile-bearing and fixed-bearing knee prostheses by simulation.

The object of the study was to model fixed-bearing knee prostheses (FBKs) and mobile-bearing knee prostheses (MBKs) during weight-bearing deep knee bends and to analyse and compare the kinematics of the two prosthesis types. To obtain quantitative data, an overall model of a leg was constructed, and this included a three-dimensional model of the tibiofemoral joint and simplified two-dimensional models of the ankle and patellofemoral joint. The simulated movement pattern of the tibiofemoral contact point in the FBK was analysed to show the posterior contact position on the tibia at full extension and anterior translation as the knee was flexed from 30 degrees to 90 degrees. The simulated maximum displacements of the medial and lateral contact positions of the FBK were 5.6 and 6.2 mm, respectively. These results were almost in agreement with experimental studies. Compared with the FBK, the movement pattern of the tibiofemoral contact point in the MBK for the anterior contact position on the tibia at full extension and posterior translation, with respect to the tibia as the knee was flexed, gave results closer to those of the normal knee. The simulated displacements of the medial and lateral contact positions of the MBK with respect to the tibia were 9.0 and 13.0 mm from full extension to 90 degrees flexion, respectively. The difference in the kinematic results between the FBK and the MBK could be accounted for by movement of the insert and the larger force of the posterior cruciate ligament on the MBK.

Biomechanical Phenomena↗

PubMed1986

New polyester arterial prostheses from Great Britain: an in vitro and in vivo evaluation.

Two models of knitted velour polyester prostheses have been developed in Great Britain, i.e. the VP1200K and the VP50K Triaxial. The evaluation of these new devices in vitro and in vivo in dogs has demonstrated that, while the first model has similar surgical, mechanical and healing characteristics in the short term to other commercial knitted velour prostheses, the second model has lower water permeability and superior strength and dimensional stability. On the basis of these results, clinical investigations can be undertaken.

Animals↗

PubMed1990

The necessity of reoperation for patients with Bjork-Shiley, St Jude Medical, Hancock and Carpentier-Edwards prostheses.

The purpose of this study was to determine the criteria of valve selection from the long-term results of Hancock, Carpentier-Edwards, St Jude Medical and Bjork-Shiley prostheses, taking into special account the frequency of reoperation. Reoperations on the Hancock bioprosthesis were performed on six patients for tissue leaflet disruption with an incidence of 2.2 per cent/patient-year. Reoperations on the Carpentier-Edwards bioprosthesis were performed on 24 patients for tissue leaflet disruption in 23 patients and prosthetic valve endocarditis (PVE) in one, with an incidence of 3.8 per cent/patient-year. Reoperations on the Bjork-Shiley prosthesis were performed in two patients for severe hemolysis, with an incidence of 0.32 per cent/patient-year. Reoperations on the St Jude Medical prosthesis were performed on 3 patients, for valve thrombosis in one patient, PVE in one, and hemolysis in one, with an incidence of 0.23 per cent/patient-year. The overall mortality rate was 20 per cent, or 7 patients, and the indications for reoperation affected this. Patients with primary tissue failure had a mortality rate of 10.3 per cent; those with a thrombosed valve, 0 per cent; those with hemolysis, 66.7 per cent; and those with valve infection, 100 per cent. A good chance of survival may be achieved in patients facing prosthetic valve complications by performing reoperation as soon as possible after early detection, since mortality is high following emergency reoperation and in patients with severe symptoms. Currently, we recommend mechanical prostheses for valve replacement except in patients over 70 years old and in younger patients with absolute contraindications to anticoagulative therapy.

Aged↗

PubMed2001

Hemolysis after mitral valve replacement with mechanical valve prostheses.

OBJECTIVE: We evaluated effects of type, size, and orientation of mechanical mitral valve prostheses on hemolysis. METHODS: Subjects were 84 patients who had undergone mitral valve replacement. Lactate dehydrogenase was mainly used as a marker of hemolysis and was measured before surgery, 1 month after surgery, and in the late postoperative period. RESULTS: Valves used included 16 Medtronic-Hall, 32 St. Jude Medical, and 36 CarboMedics valves. Medtronic-Hall valves caused less hemolysis than St. Jude Medical or CarboMedics valves in the late postoperative period. This resulted because hemolysis due to Medtronic-Hall valves was more severe 1 month after surgery than in the late postoperative period and because hemolysis due to St. Jude Medical or CarboMedics valves was more severe in the late postoperative period than 1 month after surgery. One reason for this finding is that cardiac output was greater in the late postoperative period than 1 month after surgery, making regurgitation through the pivots of bileaflet valves more severe. The orifice area and the orientation of prostheses did not affect hemolysis. CONCLUSION: St. Jude Medical or CarboMedics valves caused more severe hemolysis than Medtronic-Hall valves in the late postoperative period.

Aged↗

PubMed2000

Sarpogrelate reduces mechanical hemolysis in patients with heart valve prostheses.

OBJECTIVE: We evaluate the clinical efficacy of sarpogrelate, an antiplatelet drug that improves red blood cell deformability, to reduce the intravascular hemolysis problems suffered frequently by patients implanted with heart valve prostheses. SUBJECTS: Subjects were 34 patients undergoing mechanical heart valve replacement and having serum lactate dehydrogenase concentrations 20% above the maximum normal range. METHOD: Sarpogrelate was given daily, 100 mg orally for the first 6 months and 200 mg thereafter. RESULTS: Average serum lactate dehydrogenase decreased significantly from 423 +/- 108 IU/l, to 391 +/- 83 IU/l with the 100 mg dose, and to 361 +/- 86 IU/l with the 200 mg dose. The percentage of reticulocytes decreased from 15.5 +/- 5.3/1000 to 15.3 +/- 5.7/1000 at the 100 mg dose and 13.1 +/- 4.0/1000 at the 200 mg dose. Serum iron concentrations increased significantly from 63.2 +/- 24.8 micrograms/dl to 76.2 +/- 16.2 micrograms/dl at the 100 mg dose, and to 70.9 +/- 26.2 micrograms/dl with the 200 mg dose. CONCLUSION: Sarpogrelate is a useful drug for patients with implanted heart valve prostheses and subsequent high serum lactate dehydrogenase because it works as an antiplatelet drug and reduces mechanical hemolysis.

Adult↗

PubMed2003

[Constrained knee prostheses].

There is great controversy over constrained knee prostheses, both from a clinical and a theoretical point of view. Hinged prostheses show disadvantages such as the large implant volume, a potentially higher risk of infection, and long intramedullary stems, which are difficult to remove in cases of revision surgery. However, there are advantages as well such as simple operative procedure for implantation, primary stability without need for soft tissue balancing, and greater femorotibial congruency based on the monocentric axes for flexion/extension. Clinical long-term results remain contradictory. Implantation of a constrained prosthesis makes sense as a primary implant in elderly patients, for severe defects, deformities, and instabilities, or as a revision implant.

Age Factors↗

PubMedDate not supplied

Anatomic asymmetric prostheses: shaping the breast.

Over more than 50 years the manufacturers of mammary prostheses have offered implants of two basic shapes, sphere or teardrop, and always unilateral (symmetric). In the year 2001 Poly Implants Prothèse invited us to participate in the development of a device that, in our opinion, was going to change the conceptual design for mammary augmentation and reconstruction: the asymmetric anatomical prosthesis (AAP). On December 10, 2001 we performed, via the transareolaris inferior, the first breast augmentation using a prototype of anatomic, asymmetric, cohesive silicone implants. The result was pleasing in all aspects. The prostheses were capable to reproduce faithfully, in all dimensions, the anatomy of the female breasts, including the differences between each side. Since then, we have used the AAP with two different contents, silicone cohesive gel and Hidrogel, this last model in which we are currently experimenting. We utilized either a transareolar or submammary approach, according to the case (atrophy, ptosis, tuberous breast, etc.). We present in this paper the features of this new prosthesis, the procedures used for their implant, and a comparative analysis of our results.

Breast Implantation↗

PubMedDate not supplied

An improved method of removing polyurethane foam-covered gel prostheses.

One of the advantages of polyurethane foam-covered prostheses has been that in the first 5 to 10 years after their use, the amount of capsular contraction was found much less than when similar "slick" prostheses were used. Another advance was their fixation to the surrounding tissue thus giving a more natural appearance and movement with the muscles when the arms were moved in any direction. The formation of a thick capsule also acted as a protection against gel granuloma due to rupture of the prosthesis and has been thought to be a factor in the lower capsule contraction rate. The greatest disadvantage has been that its removal was extremely difficult and this has continued up until the technique described in this paper has been introduced.

Breast Implants↗

PubMed2001

Female-pitched sound-producing voice prostheses--initial experimental and clinical results.

In order to improve voice quality in female laryngectomees and/or laryngectomees with a hypotonic pharyngo-oesophageal segment, a sound-producing voice prosthesis was designed. The new source of voice consists of either one or two bent silicone lips which perform an oscillatory movement driven by the expired pulmonary air that flows along the outward-striking lips through the tracheo-oesophageal shunt valve. Four different prototypes of this pneumatic sound source were evaluated in vitro and in two female laryngectomees, testing the feasibility and characteristics of this new mechanism for alternative alaryngeal voice production. In vivo evaluation included acoustic analyses of both sustained vowels and read-aloud prose, videofluoroscopy, speech rate, and registration of tracheal phonatory pressure and vocal intensity. The mechanism proved feasible and did not result in unacceptable airflow resistance. The average pitch of voice increased and clarity improved in female laryngectomees. Pitch regulation of this prosthetic voice is possible with sufficient modulation to avoid monotony. The quality of voice attained through the sound-producing voice prostheses depends on a patient's ability to let pulmonary air flow easily through the pharyngo-oesophageal segment without evoking the low-frequency mucosal vibrations that form the regular tracheo-oesophageal shunt voice. These initial experimental and clinical results provide directions for the future development of sound-producing voice prostheses. A single relatively long lip in a container with a rectangular lumen that hardly protrudes from the voice prosthesis may have the most promising characteristics.

Aged↗

PubMed2004

Histological analysis and biological effects of granulation tissue around loosened hip prostheses in the development of osteolysis.

Although aseptic loosening of the prosthesis is a long-term complication after total joint replacement, the detailed mechanism of osteolysis remains unknown. We examined 82 samples from 40 patients with aseptic loosened hip prostheses histologically, and compared the distribution of particles, macrophages/histiocytes, and foreign body giant cells in the retrieved tissue from capsules and around prostheses. Furthermore, to investigate the mechanism of osteolysis, we cultured tissue from a patient with massive osteolysis and examined the effects of the conditioned medium on osteoblasts in vitro. Numerous multinucleated giant cells and histiocytes were present, and polyethylene particles ranging from medium to large were identified in the polarized light. However, the distribution was heterogeneous, and no particles were found microscopically in about 30%-40% of periprosthetic tissues, and in 60% of capsules. The amount of particles correlated with giant cells, but not with histiocytes. The conditioned medium of the granulation tissue culture stimulated osteoblasts to produce interleukin-6 in both protein and mRNA, and this was in part inhibited by anti-tumor necrosis factor-alpha or the interleukin-1beta antibody, suggesting that interleukin-6 production is mediated by several cytokines. These findings suggest that interleukin-6, which is produced not only by macrophages but also by osteoblasts, is a contributing factor to aseptic loosening.

Adult↗

PubMed2004

The safety and efficacy of a powered toothbrush on soft tissues in patients with implant-supported fixed prostheses.

The safety, efficacy and acceptability of an oscillating/rotating powered toothbrush was assessed in patients rehabilitated with fixed prostheses on implants. One hundred consecutive patients (aged 18-80; mean 56.3; 51 females), who met the inclusion/exclusion criteria and who participated in a regular annual recall scheme, were enrolled. They were instructed on how to use the powered toothbrush, as well as on classical interdental plaque control. The electric toothbrush had to be used twice daily for 2 min. The following periodontal parameters were measured at baseline and at 3 months, 6 months and 12 months: presence/absence of gingival and/or mucosal ulceration/desquamation; sulcus bleeding index; probing pocket depth; periodontal pocket-bleeding index and gingival recession. At 3 months and at the end of the study, patients completed a questionnaire concerning the overall acceptability and convenience of the powered toothbrush, as compared with their habitual manual toothbrush. A total of 80 patients completed the study. No dropouts were related to the use of the powered toothbrush. All parameters improved over the course of the study. The mean overall pocket depth decreased from 3.3 mm at baseline to 3.0 mm at 12 months, while the mean decrease in recession was 0.1 mm at 12 months. During the 1-year observation, there was a slight gain in periodontal attachment level. Gingival ulcerations were not observed at any point in the study. High scores for convenience and comfort of the powered toothbrush were reported, and the majority (95%) said that they would continue to use it for habitual oral hygiene. It is concluded that the powered toothbrush investigated is effective, safe and comfortable for patients rehabilitated by means of oral implant-supported prostheses.

Adolescent↗

PubMed1997

The stereognostic ability of natural dentitions versus implant-supported fixed prostheses or overdentures.

A stereognostic ability test was performed in 60 patients. Forty patients were rehabilitated by means of osseointegrated implants. One group consisted of 20 patients with fixed prostheses on implants in both the upper and lower jaws. The other 20 patients had a maxillary denture while in the mandible an overdenture was retained by means of two implants connected by a bar. They were compared to a group of 20 subjects (controls) with a non-restored natural dentition. For the stereognostic ability test, subjects had to recognise ten different test pieces by manipulating them with two antagonistic incisor teeth, avoiding any contact with other oral structures. Both response time and percentage accuracy of recognition were evaluated. The present findings indicated that subjects with an overdenture on implants did not score significantly different from those with an implant-supported fixed prosthesis. In contrast, subjects with teeth had a significantly better stereognostic ability. The percentage of correct responses was 52% for overdentures, 56% for fixed prostheses on implants and 75% for natural dentitions. From these results, it could be concluded that the stereognostic ability is impaired in subjects rehabilitated with osseointegrated implants by about one-third to one-quarter compared to subjects with natural teeth.

Adult↗

PubMed2001

Optimization of the resistance of arterial allografts to infection: comparative study with synthetic prostheses.

Arterial allografts can be used for in situ treatment of prosthetic graft infection. The purpose of this in vitro study was to compare the resistance of allografts and synthetic prostheses to infection by five strains of bacteria and to study antibiotic treatments designed to reduce allograft infection. Fresh and cryopreserved allografts were compared with synthetic prostheses made of various biomaterials including PTFE, plain Dacron, gelatine-sealed Dacron, and gelatine-sealed, rifampicine-bonded Dacron. Allografts were used with or without treatment using an antibiotic containing gentamycine, lincomycine, and vancomycine. The bacterial strains tested were Escherichia coli, Staphylococcus aureus, slime-producing Staphylococcus epidermidis, non-slime-producing Staphylococcus epidermidis, and Pseudomonas aeruginosa. Infection was evaluated by counting the number of adherent bacteria on the allograft or synthetic material after rinsing and ultrasonication. Statistical analysis was achieved using nonparametric Mann-Whitney tests. Results showed that allografts not treated with antibiotics were highly susceptible to bacterial infection. Antibiotic treatment decreased infection. Application of antibiotic after thawing cryopreserved allografts led to a significant decrease. None of the biomaterials tested provided sufficient protection against bacteria resistant to the antibiotics used.

Anti-Bacterial Agents↗