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PubMed1994

Silicone breakdown and capsular synovial metaplasia in textured-wall saline breast prostheses.

Saline-filled prostheses are currently the only type of prostheses available for cosmetic use in the United States because of concerns raised about the possibility of systemic toxicity of silicone-filled artificial mammary implants. Although the approved implants are saline-filled, their potential to release silicone particles from the shells has not been systematically evaluated. We performed microscopic examination of the pericapsular tissue of 54 patients with textured-surface implants and compared these with 51 patients with smooth-walled implants over a 2-year period. The capsules that had formed around virtually all textured-surface implants had silicone fragments present either in extracellular spaces, in vacuolated histiocytes, or in the form of foreign-body granulomas in surrounding fibroadipose tissue but not in capsules associated with smooth-walled implants. In 87 percent of samples of pericapsular tissue from textured saline implants, the contact surface displayed exuberant reactive synovial metaplasia, a histologic pattern not previously described with these devices. Our findings suggest that smooth-walled prostheses are associated with less silicone fragmentation than textured devices in the peri-implant tissue capsules that tend to form around artificial surfaces used for this purpose.

Breast↗
PubMed1994

Incus interposition and ossiculoplasty with hydroxyapatite prostheses.

This article traces the evolution of transplant material in ossicular reconstruction of the middle ear. The first transplant consisted of the body and short process of the homograft incus. It was repositioned or wedged between the stapes head and the manubrium of the malleus. Further modification consisted of the sculpture of prostheses from homograft incudes; these were known as the notched incus with short or long process. By means of a notch in the short process, they were locked in place. The final phase is the use of hydroxyapatite as a biocompatible material from which similar prostheses may be precisely manufactured. These hydroxyapatite prostheses, known as the incus and incus-stapes replacement prosthesis, appear to be well tolerated and to produce excellent hearing results.

Biocompatible Materials↗
PubMed1994

Autologous fibrin glue for sealing vascular prostheses of high porosity.

Thirty high-porosity double-Velour vascular prostheses were sealed with fibrin glue, the fibrinogen in the glue being prepared from citrated plasma by ethanol precipitation. After such preparation the prostheses were blood-tight at a pressure > 300 mmHg. Using a fibrin concentration of 13 mg/ml (obtained by dilution of the fibrinogen solution) the prostheses were blood-tight at a minimum pressure of 150 mmHg, which is suitable for clinical use. Sufficient fibrin glue can be prepared from 44-88 ml of the patient's blood to seal most types of high-porosity vascular prosthesis used clinically. The fibrin-sealed grafts have good handling characteristics because they are soft, pliable and non-sticky. The use of autologous fibrin glue has obvious safety advantages by preventing both transmission of viral diseases and immunological reactions.

Biomechanical Phenomena↗
PubMed1994

Predisposing factors in fixation failure of femoral prostheses following primary Charnley low friction arthroplasty. A 10- to 20-year followup study.

To identify factors affecting radiologically detected loosening of the Charnley femoral prosthesis, 326 femoral prostheses with 10- to 20-year followup were studied. After observation of postoperative radiological changes, the criteria for fixation failure detected radiologically, of femoral prostheses were defined as progression or accompanying occurrences of subsidence, demarcation, separation of the prosthesis from cement, cement fracture, or endosteal cavitation. Sixteen femoral prostheses (4.9%) developed radiologically detected fixation failure. Male gender, low canal flare index, low femoral score, large medullary canal width, low implant (cement and stem)/canal ratio, low stem/canal ratio, and varus orientation of the stem affected fixation failure. Inadequate cementing techniques such as low implant/canal and stem/canal ratios and varus stem orientation might be within the surgeon's control and should be avoided. An unfavorable canal geometry (stovepipe canal) and osteopenia of the femur, indicated by a low femoral score, are risk factors that might be out of the surgeon's control, and require future research.

Activities of Daily Living↗
PubMed1993

[A study of restoration of seriously damaged posterior teeth by cast metal prostheses].

A total of 38 seriously damaged posterior teeth were restored by cast metal prostheses, including onlays (with pulp chamber retainer and radicular retainer), cast dowelcore, two-piece dowel-core or cast dowel crown. As followed up for 6-48 months, 37 prostheses remained firm and sound, with perfect periphery seal, no secondary caries and pathological changes of peridontium were observed, The clinical consummate rate was 97%, The occlusal force of the restored teeth measured in 14 cases was 13.6-30.2 kg, which can satisfy the needs of masticatory function. The selection of retainers should be in accordance with the position and degree of crown damage of the posterior teeth. The key links guaranteeing smooth insertion and perfect periphery seal of cast metal prostheses were also pointed out.

Adolescent↗
PubMedDate not supplied

Loose gold screws frequently occur in full-arch fixed prostheses supported by osseointegrated implants after 5 years.

The possible occurrence of loose gold and abutment screws retaining full-arch osseointegrated prostheses has been investigated. The prostheses had been in use for at least 5 years. The findings were related to clinical parameters such as accuracy of the superstructure, operator dependence, and clinical and radiological diagnosis of implant status after 5 years. The principles of the California Dental Association's (CDA) quality evaluation criteria were modified and applied in the study. Gold screw loosening was found to be related to framework misfit and was considered to be operator dependent to some extent. It is recommended that full-arch fixed prostheses be retightened after 5 years.

Aged↗
PubMedDate not supplied

Complications and maintenance requirements for fixed prostheses and overdentures in the edentulous mandible: a 5-year report.

Overdentures and fixed prostheses were consecutively placed into 50 edentulous mandibles and were followed for 5 years. During this period of follow-up, 25 overdentures were supported by 68 implants with a success rate of 92.65%, and 25 fixed restorations were supported by 132 implants with a success rate of 90.15%. Postinsertion adjustment in the first year was more common for the overdentures. Thereafter, fixed prostheses had more complications and required more maintenance than overdentures, the average number of recalls per year being 2.27 and 1.57 respectively. The main complications were associated with the peri-implant mucosa, abutment and gold screws, acrylic-resin components, and retentive clips. Overdentures offer an attractive alternative to fixed prostheses in the treatment of the edentulous mandible.

Adult↗
PubMedDate not supplied

Anterior approach to total hip replacement: surgical technique and clinical results of our first one thousand cases using non-cemented prostheses.

Total hip replacement has evolved into one of the most frequently performed reconstructive procedures in orthopaedic surgery today. A modified anterior approach developed by the senior surgeon has been utilized in performing over 3,000 operations in the past two decades. It is a unique and facile exposure. It can be easily applied to primary and revision surgery. Noncemented prostheses have been used in over 1,000 of these operations. This article details the surgical exposure, acetabular and femoral preparation for both non-cemented and cemented prostheses, special considerations for revision surgery, and the clinical results of the experience with noncemented prostheses to date.

Bone Cements↗
PubMed1993

Occlusal force and mandibular movements in patients with removable overdentures and fixed prostheses supported by implants in the maxilla.

Thirteen patients with complete dentures in the maxilla were treated with implants to support a removable bar-retained overdenture for 1 year. Thereafter, the patients were provided with fixed prostheses and were followed up for another year. Maximal occlusal force and mandibular movements were recorded with and without the bar supporting the denture and then during the subsequent year with fixed prostheses. Significant changes in occlusal force capacity and mandibular movements were observed when the bar was removed. Less obvious functional changes were found when the fixed prostheses were placed, with the exception of occlusal force levels, which increased significantly over time.

Aged↗
PubMed1993

Mid-term follow-up after heart valve replacement with CarboMedics bileaflet prostheses.

The CarboMedics cardiac prosthesis (CarboMedics, Inc., Austin, Tex.) is a relatively new, low-profile bileaflet prosthesis. We report the results of a prospective mid-term evaluation of 426 CarboMedics prostheses implanted at our institution. Three hundred fifty patients had CarboMedics prostheses implanted in the mitral (n = 125), aortic (n = 149), or aortic and mitral positions (n = 76). Hospital mortality was 5.2%. Follow-up was 98% complete, with 478 patient/years and a mean follow-up of 19 months (range 1 to 42 months). Actuarial freedom from complications were calculated as follows (linearized rates in parentheses): late mortality 97% +/- 0.77% (2.7%), thromboembolism 98% +/- 0.4% (0.5%), anticoagulation-related hemorrhage 98.6% +/- 0.4% (0.4%), nonstructural dysfunction 98.5% +/- 0.6 (0.2%), valve-related mortality 91.5% +/- 0.7 (0.5%), valve failure 90.9% +/- 1% (0.7%), treatment failure 92.8% +/- 0.8% (0.7%), and all valve-related morbidity and mortality 90% +/- 2% (2.6%). According to our results, the CarboMedics valve has a low rate of complications that further improves the quality of life in patients with heart valve prostheses.

Adolescent↗
PubMed1993

Effect of age on progression through temporary prostheses after below-knee amputation.

Forty six patients that underwent below knee amputation for diabetes, trauma/osteomyelitis or peripheral vascular disease were studied. Healing was estimated by the rate of progression through temporary prostheses as determined weekly by the amputee rehabilitation team (physiatrist, orthopedist, physical therapist, nurse, and prosthetist). For all groups combined, mean days +/- standard error from amputation to above knee cast with pylon and foot (AKPy) were 22.9 +/- 1.9, to below knee cast with pylon and foot (BKPy) 41.6 +/- 2.8 and to laminated temporary prostheses 66.5 +/- 4.5. A regression analysis of these variables on age (range: 29 to 84 yr) showed significant positive correlations for AKPy (r = 0.34, P = 0.0214) and BKPy (r = 0.40, P = 0.0056). An analysis of variance with contrasts (Tukey's protected t) showed significant lower values (P < 0.05) for amputation to BKPy in the trauma/osteomyelitis group when compared to diabetes or peripheral vascular disease and no difference among the last two groups. However, when variables were adjusted for age (analysis of covariance with age as a covariate), the differences among groups disappeared (covariance F(2,44) = 0.9, P > 0.4). In conclusion, age, not the cause of the amputation, correlated with healing after below knee amputation as estimated by the rate of progression through temporary prostheses.

Adult↗
PubMed1993

Are total hip prostheses implanted with the use of methylmethacrylate biocompatible?

OBJECTIVES: The biocompatibility of total hip replacement prostheses and methylmethacrylate cement which is used for fixation of the prosthetic components has been subject to debate for three decades. METHODS: We have studied the host response to total hip replacement prostheses in a number of clinical and experimental investigations. RESULTS: Methylmethacrylate cement is immunologically relatively inert while it causes, in in vitro experiments and in vivo, a foreign body type of reaction. In cementless prostheses, the wear of polyethylene which is used for lining of the acetabular component causes a similar foreign body type of reaction. CONCLUSION: Ultimately, the total hip prosthesis cannot be made invisible to the host system. The host response can be controlled and reduced, but not eliminated by technical improvement and development of more biocompatible materials.

Biocompatible Materials↗
PubMedDate not supplied

Acid-etched, resin bonded cast metal prostheses: a retrospective study of 5- to 15-year-old restorations.

Eighty-five resin bonded prostheses were evaluated in a retrospective study over a 15-year period. All had been in function for at least 4.5 years. Multifactorial variables were studied to ascertain their effect on debonding and the health of the oral tissues. The results showed: (1) the caries rate of the retainer teeth was 6%, (2) the mean gingival indices for the prostheses were significantly higher (P > .0001) than those of the remaining dentition, (3) 61% of the restorations had not debonded (if failure resulting from trauma was not included, the incidence of debonding dropped to 19%), and (4) all patients liked their prostheses.

Analysis of Variance↗
PubMed1993

Mechanical prostheses: old and new.

The four mechanical valve prostheses currently available on the U.S. market have evolved from a field of more than 50 valves produced for human implantation since the early 1950s (Tables 11-1 to 11-4). This literature establishes that good results can be achieved with a number of cardiac prostheses if properly used and monitored after implant. The current generation of valves have demonstrated ease of implantation, improved durability, good hemodynamic performance, and reduced thromboembolism and thrombosis with proper anticoagulation. The cost and complexity of completing PMA by the FDA, concern over product liability, and patent rights on design and raw materials have narrowed the choice of devices for surgeons in the United States and slowed the pace of new market entries. The evolution of mechanical valves has been reviewed and modes of valve failure reviewed when pertinent. Clinical expectations for earlier generation devices and present valves also are reviewed. Prostheses under evaluation are discussed along with considerations for valve implantation, surveillance, and anticoagulation. We have employed the SJM valve since about 1985. The proven good hemodynamic performance in small sizes and low profile have made its application well suited to the pediatric population and for smaller aortic roots. The well-guarded hinge mechanism and low probability for disc entrapment have facilitated its use in chordal sparing mitral replacements in our experience. Application in the tricuspid position also has been successful but requires close attention to anticoagulation.

Heart Valve Diseases↗
PubMed1993

Gastrocnemius muscle flap coverage of exposed or infected knee prostheses.

A retrospective analysis was performed of 12 patients who required soft-tissue coverage of an exposed or infected total knee prosthesis between 1982 and 1989. All knees had skin closure with medial gastrocnemius muscle flaps. At a mean follow-up period of 41 months, all patients who were treated for infected prostheses with removal of the implant, intravenous antibiotics, and muscle flap closure had an excellent clinical result with complete skin coverage and no infection. Five of the six patients went on to successful reimplantation. Of the patients with an exposed prosthesis, five of six had an excellent outcome with retention of the prosthesis. Thus, 11 of 12 patients (92%) who had medial gastrocnemius flap coverage of an exposed or infected knee prosthesis had an excellent outcome, with ten of 12 patients (82%) retaining their prostheses or having a successful reimplantation. No medial gastrocnemius flap failed after standard primary or revision total knee arthroplasty. Gastrocnemius muscle flaps provide excellent soft-tissue coverage of exposed or infected knee prostheses and facilitate surgical care of this difficult problem.

Adolescent↗
PubMed1995

[Double valve replacement with mechanical prostheses--an operative results].

From January 1980 to December 1993, sixty eight patients underwent double valve replacement with mechanical prostheses. There were forty males and twenty-eight females with a mean age of 49.6 years (ranging from 30 to 68 years). They were classified 10 of NYHA class IV, 28 of class III. Twelve patients had previous cardiac operation. TR was identified in 20 patients. DVR was performed in 53 patients, DVR + TVR in one, DVR + TAP in 13. Twenty-two had St. Jude Medical (SJM) prostheses and 46 had Björk-Shiley (BS) prostheses. Early death before 30 postoperative days occurred in 6 patients (8.8%). MOF was the most frequent cause for early death. The risk factors for early death were the NYHA class IV, infective endocarditis, longer duration of cardiopulmonary bypass, necessity of postoperative IABP support. Other factors such as emergency operation, previous operation, tricuspid valve surgery, duration of aortic cross clamp time were not the predictors for early death. Cumulative follow-up was 284.0 patient years (PY). The rate of late survival was 74.1% (40 patients). Linearized rates of thromboembolism (TE), prosthetic valve endocarditis (PVE), hemolysis (H), reoperation (RO) were 2.8%/PY, 0.7%/PY, 0.4%/PY, 1.1/PY respectively. The free rates from TE, PVE, H, RO at nine years were 75.6%, 96.2%, 93.1%, and 89.8%, respectively. The cumulative survival rates at 14 years were 53.2% in over-all patients, and 64.3% in hospital survivors. We conclude that the early surgery is recommended for the patients with multiple valvular heart disease. The late outcomes of DVR with SJM or BS mechanical prosthesis is an acceptable one.

Adult↗
PubMed1996

Fluoroscopic functional evaluation of bileaflet prostheses: effect of different intraoperative valve orientation.

Fluoroscopy is a reliable, easy, and readily available technique to follow-up prosthesis functioning after heart valve surgery. The different orientation given to the prosthesis may represent a limitation of the technique accounting for unsatisfactory results in 10% to 40% of the cases. The aim of the study was to evaluate whether and to what extent different intraoperative valve orientation influence feasibility and accuracy of postoperative fluoroscopic evaluation of bileaflet prostheses. We prospectively evaluated 90 patients who had aortic, mitral, and/or tricuspid valve replacement with Sorin Bicarbon or CarboMedics bileaflet prostheses. Fifty percent of the patients in each group were randomly assigned to receive prostheses oriented in a perpendicular or a parallel position with respect to the ventricular septum. Fluoroscopic evaluation was considered appropriate when the prosthesis' "tilting disk" projection was obtained. The valve's hemodynamic performance was investigated through Doppler study. A proper fluoroscopic evaluation was rapidly (15 +/- 5 seconds) achieved in all patients with the former orientation, whereas it was impossible to obtain it in 8 of 20 (40%), 19 of 20 (95%), and 4 of 5 (80%) of patients with the latter orientation. In the remaining patients extremely angulated, uneasy projection was often required to get a correct fluoroscopic image. The Doppler study showed a similarly favorable hemodynamic performance regardless of valve orientation. Prosthesis orientation crucially affects the rate of success of the fluoroscopic evaluation. The orientation perpendicular to the ventricular septum greatly facilitates the postoperative feasibility and accuracy of fluoroscopy, and it is not detrimental to the valve's hemodynamic performance. This valve orientation may provide a better fluoroscopic window whenever a valve dysfunction is suspected.

Aortic Valve↗
PubMed1996

Combined vascular reconstruction and adjunctive tissue transfer in the treatment of infected arterial prostheses and tissue defects.

One of the most serious complications in vascular surgery is infection of the vascular arterial prosthesis (VAP) which might lead to loss of limb or even death. Very often infected prostheses are combined with infectious infiltration of the adjacent tissues or even necrosis and their loss. This paper deals with the experience in the management of 5 patients suffering from infection of vascular arterial prostheses in various locations, for by-passing abdominal aorta and distal arteries with loss or necrosis of the skin and tissues adjacent to the graft. Removal of the infected graft was performed in all of the cases, together with wide debridement of the infested area and placement of a new graft, coursing far from the infected area for revascularization of the affected limb. The cleaned infected area was covered at a first or second stage by applying plastic procedures utilizing musculocutaneous tissue transfer. The results were quite satisfactory. We conclude that the management of infected vascular arterial prostheses, when these are combined with loss of adjacent tissues, is a challenge for the Vascular Surgeon. Their removal, extended cleaning and covering of the area by means of plastic procedures with tissue transfer, proved to be effective in the management of this problem.

Blood Vessel Prosthesis↗