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At least 73 records · Page 4Linked to original sources
PubMed1998

Prosthodontic problems and limitations associated with osseointegration.

When compared with any other surgical or prosthodontic procedure, osseointegration has offered the greatest improvement in quality of life for patients who suffer with the effects of an edentulous condition. Results have been dramatic both functionally and from the aspect of patient satisfaction. However, a level of complication and compromise remains that limits overall patient and practitioner satisfaction. This article critically analyzes the existing literature relative to prosthodontic problems and complications of osseointegration for the edentulous patient. An attempt is made to compare the documented frequency of complication versus the perceived potential for complications, including implant failure, prosthesis misfit, component fracture, and screw loosening.

Alveolar Bone Loss↗
PubMed1986

Failure of the Jonas prosthesis.

A total of 27 patients received the standard Jonas silicone-silver penile prosthesis. The procedure was done at 3 separate hospitals by 2 surgical teams. Four patients who were reported on previously presented consecutively to our clinic with failed penile rigidity and complete multiple wire fractures were found at reoperation. Therefore, the remaining 23 patients were reviewed and 7 had positive findings suggesting fracture, including decreased penile rigidity, crackling that was audible or palpable and/or evidence of fracture on an x-ray. Seven patients had completely negative evaluations and 9 were lost to followup. Two patients with suspicious x-ray findings and 1 with negative x-ray findings but who reported less rigidity have since had the prostheses removed, and all had multiple wire fractures. Radiographs of fractured prostheses, both in the penis and explanted, attest to the limited reliability of x-ray in the diagnosis of wire fracture.

Humans↗
PubMed1997

The value of postmortem retrievals in the analysis of long-term, well-functioning cemented femoral stems.

Multiple sections from long-term, low-friction bilateral Charnley prostheses harvested from two patients who died 20 and 22 years after the primary implantation were studied. All sections showed generally sound mechanical integrity at both the cement-bone and cement-metal interfaces, in spite of localized evidence of cement fracture and debonding. The host tissues showed no clear evidence of an adverse biologic response toward the implant. These findings aided in the delineation of the sequence of biologic and mechanical events that lead to prosthesis failure. They suggest that if the apparently unavoidable mechanical deterioration of cemented implants can be limited by good fixation between the host and prosthesis, then disastrous biologic events, such as osteolysis, may be avoided, and long-term function, preserved.

Autopsy↗
PubMed1985

Bioprostheses for cardiac valve replacement.

Biologic tissue has been used successfully for cardiac valve substitutes since the introduction of glutaraldehyde preservation in 1969. Assessment of the clinical performance of prosthetic valves requires consideration of thromboembolism, anticoagulant-related hemorrhage, prosthetic valve endocarditis, periprosthetic leak and prosthesis failure. Two methods of assessment of valve performance, linearized occurrence rates and multiple decrement analysis of valve-related complications, are illustrated in evaluation of previous and new-generation Carpentier-Edwards porcine bioprostheses. The standard valve has a valve-related complication rate of 2.9% per patient-year over 5 years, while the rate for the new-generation supra-annular prosthesis is 4.3% per patient-year in the 2-year interval. Thromboembolism has been 1.6% and 1.7% per patient-year, respectively, for the previous and new-generation prostheses. Primary tissue failure has occurred only in the standard prosthesis, 0.6% per patient-year. The freedom from all valve-related complications is 93.1% at 2 years and 87.5% at 6 years with the standard valve and 95.1% at 2 years with the new-generation prosthesis. Standardized assessment of prosthetic performance should provide physicians and surgeons with the knowledge to optimize patient management. The new-generation biologic prostheses with improved preservation should reduce calcification and fatigue lesions. Tissue valves have afforded patients an excellent quality of life with a low incidence of valve-related complications.

Bioprosthesis↗
PubMed2000

The design of a finger wear simulator and preliminary results.

A dual-cycle finger wear simulator has been designed, manufactured and commissioned. The simulator interspersed dynamic flexion-extension motion under light load with a heavier static 'pinch' load to a test prosthesis immersed in a lubricant heated to 37 degrees C. A validation test was undertaken on a size 2 Swanson prosthesis, leading to prosthesis failure in less than 1 million cycles. A second test was carried out on a Durham metacarpophalangeal prosthesis. After 4.8 million cycles a total wear factor for the joint of 0.60 x 10(-6) mm3/N m was calculated, with no cracks or damage visible. Both test results compare well with earlier tests undertaken on the Stokoe finger wear simulator.

Artificial Limbs↗
PubMed2001

Statistical analysis of failure times in total joint replacement.

Time to revision is an important criterion describing the quality of implants in total joint surgery. Estimates of failure probabilities are required to inform a patient about the risk of suffering a reoperation. Also, regression models are used for comparing different prosthesis designs. Typically, patients dying before a revision are considered as censored for time to prosthesis failure. We argue that this technique is inadequate for estimation of failure probabilities and insufficient for comparison of different designs. We propose a new approach based on a competing risk model to account for concurrent mortality. We describe differences in the estimation of failure probabilities and in the interpretation of regression models for implant failure. Additionally, we introduce a random effects term in the regression model to account for potential dependencies in the failure times of bilaterally treated patients. The new approach is illustrated with fictitious data and data from an observational study conducted at a specialized hospital in Switzerland.

Aged↗
PubMed1984

Hemi-replacement arthroplasty of the proximal humerus. A case report.

A ten-year-old girl underwent excision of a chondrosarcoma of the right proximal humerus with subsequent insertion of a prosthesis. Failure of the device occurred six years after operation, requiring revision to an identical but shorter prosthesis. This device failed 1 1/2 years later and was replaced by a fibular graft inserted in the humeral medullary canal. The fibular graft was removed 18 months later, resulting in a flail right shoulder. The mode of failure in each instance was anterior and superior dislocation of the hemiarthroplasties. Currently, ten years after the initial procedure, the patient is tumor free with a shortened functional right upper extremity.

Bone Neoplasms↗
PubMedDate not supplied

[St. Georg knee endoprosthesis system (slide and hinge principle). Observations and results following 10 years' experience with over 3,700 operations].

Some 2000 total knee endoprostheses were inserted from 1970-1978 and about 1700 of these have been followed two different types of knee replacement were used, a surface replacement of a non-constrained design and a total hinge prosthesis. Serious complications, such as infection, loosening and fracture of the components were regarded as significant determinants in the evaluation of the durability of total and partial knee replacement. The highest and lowest incidence of complication were recorded. The longevity of knee arthroplasty and the survival rates were estimated by constructing survivorship tables. Patients with knee replacement having no complications were designated "survivals" while patients with an established complication were treated as "deaths". The success rates of total hinge prosthesis were compared with those of the sledge prosthesis. Failure rates of aseptic complications were assessed and compared with failure rates due to septic complications. A differentiation was also made between the sledge prosthesis and the total hinge prosthesis. Furthermore, significant differences in the indication for the insertion of the sledge or the total hinge were determined by group assessment (log-rank-test). Unlike the general trend to use a semiconstrained knee replacement the evaluation of this clinical trial has induced us to improve our hitherto used total knee prosthesis model rather than to develop a new surface replacement.

Follow-Up Studies↗
PubMed1996

Elevated circulating levels of von Willebrand factor and D-dimer in patients with heart failure and mechanical prosthesis.

To test the hypothesis of association between heart failure and altered haemostatic balance in patients with a mechanical valve prosthesis, comparisons were made between 20 patients with mitral valve replacement and stable chronic heart failure (group A), 20 with the same prosthesis but satisfactory haemodynamics (group B) and 20 age-matched controls (group C). The left ventricular ejection fraction was significantly highest (p < 0.001) in group A. The pulmonary artery systolic pressure was also highest in group A (p < 0.001), without significant difference between groups B and C. Two group A patients had a transient ischaemic attack. The D-dimer plasma concentrations and the antigenic and biologic von Willebrand factor activities were significantly greatest in group A. Significant correlation was found between the plasma concentrations of these activities and pulmonary artery systolic pressure and between D-dimer and ejection fraction. Platelet-activating factor was detected only in six group A patients. The observed relationship between haemostatic factors and heart failure in patients with mechanical heart-valve prosthesis advocates careful evaluation of von Willebrand factor and D-dimer in order to prevent embolic events in such cases.

Atrial Function↗
PubMed2006

Latissimus dorsi muscle flap and tissue expansion for breast reconstruction.

BACKGROUND: After mastectomy for breast cancer, especially when combined with radiation, inadequate wall thickness and insufficient elasticity of the skin are problems frequently encountered in breast reconstruction. We describe a reconstruction method using a latissimus dorsi muscle flap, followed by expansion, that creates no additional scar. METHODS: This retrospective study included 30 patients who underwent this 4-surgery reconstruction: the muscle flap was raised and drawn through the mastectomy scar; the expander was inserted; expander replacement with the definitive prosthesis and concomitant symmetrization of the contralateral breast; finally, reconstruction of the nipple-areola complex. RESULTS: Only 1 failure, prosthesis extrusion, was observed. A surgeon scored the outcomes as above average for 26 women, who were satisfied. DISCUSSION: We noted an overall lower complication rate and a lower reconstruction-failure rate compared with reported results. This approach obtained better tissue quality; the flap provided better covering thickness and expansion, yielding a larger muscle-skin pocket. CONCLUSIONS: This reconstruction procedure seems reliable and extends the indications of skin expansion, with satisfactory results.

Adult↗
PubMed1992

Use of penile prostheses to maintain external condom catheter drainage in spinal cord injury patients.

This is a retrospective analysis of 79 spinal cord injury patients who have had penile implants from one to 14 years. The primary indication for implants was the loss of condom catheter with a small retractile penis. Mean period after injury to when the implants were placed was 8.24 years (range 1-21 years). Mean total length of time the implants have been followed was 7.08 years (1-14 years). Sixty patients responded to our detailed questionnaire and they have been subjected to further analysis: prior to the implant 46 patients (77%) frequently lost their condoms. Fourteen of the patients (23%) had indwelling catheters, and 3 (5%) had a suprapubic cystostomy since they could not retain an external condom for urinary drainage because of retraction of a small penis. Post implant, 81% of patients had no accidents involving condom loss, while 19% still lost condoms. All indwelling catheters could be removed except for one patient who continued with a suprapubic catheter following transurethral sphincterotomy (TURS) and a penile implant. Sixty-eight percent used the implant for sex and felt their wives were satisfied. Patient satisfaction survey showed a markedly increased self esteem, increased mobility without fear of condom loss, and an improved sex life. Overall, the long term prosthesis failure rate was 8%. The specific infection complication rate was less than 2%. The Flexirod semirigid, hinged prosthesis proved ideal in meeting the requirements for these patients.

Adult↗
PubMed1999

[Middle ear ossicular replacement prostheses: cause of failure].

There are various prostheses used for ossiculoplasty in chronic middle ear disease. Plastipores are one of the most commonly used prostheses. We performed ossiculoplasty with plastipores in 237 ear operations in a five years period. The results of the operations were summarized and causes of prosthesis failure were discussed. In 55 (23.2%) patients, tympanic membrane perforation recurred. Cholesteatoma recurrence was encountered in 16 (6.8%) cases. The extrusion of prosthesis was observed in 10 (4.2%) cases. The underlying ear disease was cleaned in 156 (65.8%) patients. An air-bone gap to within 20 dB was achieved in 87 (55.8%) ou of 156 patients. In 69 (44.2%) the gap closure was more than 20 dB. The experience of the surgeon in otologic surgery, severity of the chronic ear disease, status of the eustachian tube, extention of the ossicular chain disruption, type of surgery and characteristics of the prosthesis are critical for ossiculoplasty.

Adolescent↗
PubMed2000

Early catastrophic failure of rotating hinge total knee prosthesis.

The mechanical failure of a prosthesis component is usually observed as a late complication of total knee arthroplasty (TKA). In knees with severe ligament instability and bone deficiency, either a true hinge prosthesis or a rotating hinge implant is commonly used. Failure of the polyethylene bearing bush in a hinge-type prosthesis is a complication that has not been reported to date. We report the cases of 2 rotating hinge TKA prostheses that dislocated as a result of mechanical failure of the prosthetic component within 5 months of initial implantation. Clinicians should be aware of this potential complication when selecting rotating hinge prostheses for certain patients.

Arthroplasty, Replacement, Knee↗
PubMed1992

Morphologic findings and causes of failure in 24 explanted Ionescu-Shiley low-profile pericardial heart valves.

From 1981 to 1987 just over 608 Ionescu-Shiley low-profile bovine pericardial bioprostheses were implanted at the Toronto Hospital. Twenty-four prostheses (11 aortic and 13 mitral) were surgically explanted from 1988 to 1990 from 20 adults (10 men and 10 women). Prosthesis failure was caused by primary tissue failure in 17 valves or by other mechanisms in seven valves. Variable degrees of tissue failure were also seen in four of the seven valves from the latter group. Primary tissue failure was characterized by fluid insudation between collagen bundles, para stent post tears (alignment stitch related, 20 valves), cusp perforation with prolapse, and calcification. The earliest cusp tears occurred at 28 months. Calcification (10 of 24 cases) was minimal in seven of 10 valves (occurring primarily at the margins of the torn cusp), moderate in two, and severe in one. Tissue overgrowth (pannus) was seen in all but three prostheses. Like its predecessor, the Ionescu-Shiley standard pericardial valve, this prosthesis failed at 2 to 5 years largely due to design-related (alignment stitch) causes and tissue degeneration. Calcification was less prominent, while tissue overgrowth (pannus) was more marked.

Adult↗
PubMed1986

THARIES resurfacing arthroplasty. Evolution and long-term results.

The unsatisfactory results of total hip arthroplasty in the young patient led to the development of the concept of hip resurfacing. Total hip articular replacement by internal eccentric shells (THARIES) resurfacing was introduced in 1975, with the primary goal of bone stock preservation and the hope of increased durability in the young patient. Major changes in design and technique include thicker and more uniform acrylic layers, metal-backed flanged acetabular component, and reduction in femoral size for preservation of acetabular bone stock. Of the 584 hips (average patient age, 48 years) with one- to ten-year follow-up study, there have been 72 failures (revision rate, 12.3%) with 66 cases of loosening (nearly all beginning in or limited to the acetabular side), two neck fractures, and four sepses. Survivorship analysis revealed that the single most important factor related to prosthesis failure is age followed by diagnosis and experience of the surgeon. Osteoarthritis and rheumatoid arthritis were favorable categories with congenital dysplastic hip (CDH), osteonecrosis, and previous failed resurfacing being unfavorable categories. Experience has taught the importance in preserving acetabular bone stock, providing bone graft for socket coverage in severe dysplasia, and removing dead bone in osteonecrosis. While resurfacing did not solve the problems of the young patient, even those patients who failed often gained time for application of the newer techniques and materials. The femoral component infrequently failed. The head remained vascular. This leads the authors to conclude that the surface arthroplasty concept is a viable alternative to total hip arthroplasty and seems to be ideal for the application of porous technology.

Adult↗
PubMed1990

Lipid accumulation in prosthetic vascular grafts. Experimental study.

The present study demonstrates that the endoprosthetic tissue, developed at the contact of Dacron and Gore-Tex vascular prostheses replacing the infrarenal aortae of healthy dogs, presents a particular lipidic pattern as compared with the adjacent intimal arterial layer. The modified lipidic pattern is characterized by a significant increase in the total amounts of cholesterol, phospholipids, and triglycerides, despite a normal lipidic plasma profile. Histochemical studies showed that lipid droplets are accumulated in the cytoplasm of deeply situated cells and in the extracellular matrix. These findings support the idea that lipids may be trapped within the pseudo-intima of synthetic vascular grafts, even in the absence of a major plasma lipid disorder, and contribute to the prosthesis failure.

Animals↗
PubMed1988

Mechanical failure of OmniPhase penile prosthesis.

We report a case of mechanical failure due to cable breakage in both cylinders of an OmniPhase penile prosthesis. The failure occurred six weeks after implantation and was manifested by inability to activate the device. X-ray films showed cable fracture at the point of insertion into the activator mechanism bilaterally. This failure appears to be an isolated episode, and the prosthesis has been successfully replaced with a similar device.

Erectile Dysfunction↗