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PubMed1982

Arterial regeneration over absorbable prostheses.

Small-vessel arterial replacement by a prosthetic material elicits inflammatory and regenerative reactions that alter the patency rate of the resultant prosthesis-tissue complex. Woven absorbable polyglycolic acid prostheses, 24 mm in length, were implanted into adult rabbit aortas and followed for 7 1/2 months. At the time the animals were killed, 45 specimens were studied grossly and by arteriography, light and electron microscopy, immunohistology, and bursting-strength determinations. No rabbit died of aortic-related complications. Mild dilation occurred in 11% (five specimens), and intimal hyperplasia occurred in 13% (six specimens), with 76% (34 specimens) displaying parallel walls at the original 3- to 4-mm diameter. Microscopy showed that the prostheses were replaced by regenerating endothelialized vessels containing smooth musclelike myofibroblasts and dense fibroplasia, without thrombosis or infection. All withstood saline solution infusion at three to five times the systolic pressure. Results of these studies demonstrate conditions that permit arterial regeneration over absorbable scaffolds.

Animals↗

PubMed1987

Arterial regeneration over polydioxanone prostheses in the rabbit.

We analyzed histologic, ultrastructural, and functional characteristics of rabbit aortic conduits regenerated over absorbable polydioxanone prostheses. Twenty-eight polydioxanone-elicited prosthesis/tissue complexes harvested two weeks to 12 months following implantation were analyzed grossly; photographed; sectioned for light, scanning, and transmission electron microscopy; and studied for compliance, bursting strength, and prostacyclin and thromboxane metabolite contents. No aortic-related deaths or hemorrhages occurred. Smooth regenerated conduits without stenoses were seen in 27 of 28 specimens, with one small aneurysm. Transprosthetic myofibroblast migration and proliferation paralleled the kinetics of macrophage-mediated prosthetic dissolution, which was consequently delayed compared with polyglycolic acid prostheses. Confluent endothelial-like luminal surfaces were present after two weeks. Progressive inner capsular thickening ended after three months at 420 micron. Ex vivo compliance curves resembled arterial elasticity. Regenerated tissue withstood 1200 mm Hg of systolic pressure, and 6-keto-prostaglandin F1 alpha to thromboxane B2 ratios did not differ from normal control specimens.

6-Ketoprostaglandin F1 alpha↗

PubMed1989

Plasma polymerized tetrafluoroethylene/polyethylene terephthalate vascular prostheses.

Tetrafluoroethylene (TFE) was discharged onto woven polyethylene terephthalate (PET) prostheses, and the PET prostheses (50 mm long) with or without TFE were implanted into canine carotid arteries and aortas. Additional controls included polytetrafluoroethylene and Dacron. Specimens were explanted after one to 12 months, photographed, and sectioned for light and scanning and transmission electron microscopy, and thrombus-free surface areas calculated by computerized planimetry. Results showed no significant patency differences among carotid or aortic groups. However, both PET carotid groups had significantly greater thrombus-free surface areas. Histologically, both PET groups appeared identical. An endothelialized neointima covered PET carotid specimens by six months, compared with three months in the aortic position, with greater pannus ingrowth in both PET groups. Plasma polymerized TFE offered no additional advantage in these long-term experiments.

Animals↗

PubMed1999

Cancer risk among patients with finger and hand joint and temporo-mandibular joint prostheses in Denmark.

The use of artificial joint implants has risen greatly over the past years. However, few investigations of the cancer risk associated with implants have been performed. We investigated cancer risk in patients with finger and hand joint and temporo-mandibular (TMJ) joint implants. A nationwide cohort in Denmark of patients with finger and hand joint prostheses (n = 858) or TMJ implants (n = 389) was followed from January 1, 1977, to December 31, 1995, to evaluate any potential cancer risks subsequent to receiving these implants. Standardized incidence ratios (SIRs) for all cancers were 1.0 (95% CI = 0.8-1.2) for the finger and hand joint cohort and 1.1 (95% CI = 0.8-1.7) for the TMJ cohort. A significant risk for non-Hodgkin's lymphoma was found in the finger and hand joint cohort (SIR = 3.8, 95% CI = 1.5-7.8). When the finger and hand joint cohort was stratified by diagnosis of rheumatoid arthritis, the excess risk was seen only in the group with rheumatoid arthritis. This is consistent with past studies, which have found an association between rheumatoid arthritis and non-Hodgkin's lymphoma. Our results provide evidence that the cancer risk for patients with finger and hand joint prostheses and TMJ implants is similar to that for the general population.

Aged↗

PubMed1996

Heterogeneity in cellular and cytokine profiles from multiple samples of tissue surrounding revised hip prostheses.

Previous studies have attempted to define the biologic properties of the bone-implant interface using a single specimen harvested from the periprosthetic tissues. The purpose of this study was to examine the heterogeneity in cellular and cytokine profiles of multiple samples taken from the tissues surrounding revised hip prostheses. Clinical and radiographic data for nine patients undergoing surgical revision was gathered prospectively. Three tissue samples were taken systematically from the acetabular and/or femoral bed. Morphologic characteristics of the tissues were assessed using hematoxylin and eosin-stained sections. Immunohistochemical staining was performed using monoclonal antibodies to identify macrophages (EMB11 and CD68); activated macrophages (Leu M3); total T lymphocytes (Leu 4 and T11); T-helper lymphocytes (Leu 3A and CD4); cytotoxic/suppressor T lymphocytes (Leu 2A and CD3); and fibroblasts (5B5). In situ hybridization was used to identify the mRNA for specific proteins: interleukin (IL)1 alpha and -beta, IL-2, IL-6, transforming growth factor beta, tumor necrosis factor alpha (TNF alpha), platelet-derived growth factor alpha (PDGF alpha), and interferon gamma. A quantitative assessment was performed for each section by calculating the percentage of positively staining cells using a light microscope and grid-counting technique. A random effect analysis of variance was calculated to determine both the variance between samples within each patient and the variance between different patients. Standard deviations contributed by sampling variance and patient variance were calculated and an F test was applied. Tissue samples taken from different regions of the bone-prosthesis interface showed marked heterogeneity in cellular and cytokine profiles. Critical F values indicating a statistically significant degree of variance between different tissue samples were exceeded for macrophages, cytotoxic/suppressor T lymphocytes, and T-helper lymphocytes. The cytokine profile was significantly different for IL-2, PDGF alpha, and TNF alpha. This tissue heterogeneity may be due to different mechanical and biologic environments along the bone-prosthesis interface. Thus, caution must be exercised in defining the biologic properties of the tissue surrounding revised prostheses according to a single biopsy.

Adult↗

PubMed1997

Adhesion to silicone rubber of yeasts and bacteria isolated from voice prostheses: influence of salivary conditioning films.

Adhesion of yeasts and bacteria to silicone rubber is one of the first steps in the biodeterioration of silicone rubber voice prostheses. In this paper, adhesion of two streptococcal, staphylococcal, Candida albicans and Candida tropicalis strains, isolated from explanted voice prostheses was investigated to silicone rubber with and without a salivary conditioning film in a parallel-plate flow chamber. Within each microbial pair of one species, the strain with the most negative zeta potential adhered most slowly to negatively charged silicone rubber. No other clear relationships were obvious between adhesion to silicone rubber and microbial zeta potentials of cell-surface hydrophobicities, as by water contact angles. A 1.5-h adsorbed salivary conditioning film appeared to possess components, presumably albumin and lysozyme, slowing down the deposition of the yeasts and some of the streptococcal and staphylococcal isolates. In addition, microbial adhesion in a stationary end point was generally lower to silicone rubber with an adsorbed salivary conditioning film than without one. Nearly all microorganisms adhering to an adsorbed salivary conditioning film, yeasts as well as bacteria, were stimulated to detach by the passage of an air bubble through the chamber, but microorganisms adhering directly to the silicone rubber, especially C tropicalis strains, detached in far lower numbers under the influence of a passing air bubble. The present observations are in agreement with clinical in vivo findings that in patients with reduced saliva production after radiotherapy, the device life of the voice prosthesis is significantly shortened and suggests that isolated salivary components might be used as an anti-adhesive.

Bacteria↗

PubMed1997

Failure mechanisms of anterior cruciate ligament prostheses: in vitro wear study.

Previous retrieval studies analyzing the cause of failure of anterior cruciate ligament (ACL) prostheses identified a wear mechanism. However, the relative importance of yarn on bone compared to yarn on yarn wear has not been clearly understood. Therefore, the objective of this study was to elucidate which type of wear is the dominant cause of clinical failure. A variety of ACL prosthetic structures were exposed to two in vitro tests: one for yarn on yarn and the other for a novel yarn on bone wear test system. The latter included the use of both smooth (uncut) and rough (cut) bone surfaces to simulate the conditions around the condyle and at the exit of the tibial tunnel, respectively. The damaged textile structures were viewed by SEM. The various fiber fracture morphologies were identified and classified for the two types of wear tests; for the smooth and rough bone surfaces; for the braided, knitted, woven, and twisted textile structures; and for the three types of fibers that were included: polyethylene terephthalate, polypropylene, and ultrahigh molecular weight polyethylene. The results confirmed that yarn on bone and yarn on yarn wear phenomena are associated with significantly different failure mechanisms. While the more aggressive rough (or cut) bone causes more rapid and intense fiber damage and faster ACL failure than the smooth (uncut) osseous surface, both abradants cause the same type of abrasive wear phenomenon. Differences in failure mechanisms were identified between the different textile structures and the different fiber types. By interpreting the damaged fiber images from clinically failed and retrieved ACL prostheses, we are now able to confirm that the predominant cause of synthetic ACL failure is yarn on bone abrasion. Improvements in future ACL prosthesis designs will only be possible by eliminating or minimizing the effect of this type of abrasive wear.

Anterior Cruciate Ligament↗

PubMed1979

A study of arterial prostheses by scanning electron microscopy.

Scanning electron micrographs were taken of ten different vascular prostheses. The micrographs showed that some prostheses were damaged and some had traces of chemicals on their surface. The application of standard vascular clamps damaged most grafts and some showed remarkable changes on resterilization.

Arteries↗

PubMed1988

Effects of autologous mesothelial cell seeding on prostacyclin production within Dacron arterial prostheses.

Canine abdominal aortas have been replaced with Dacron arterial prostheses to assess the effects of mesothelial cell seeding on graft prostacyclin and thromboxane A2 release. At both 2 weeks and 6 weeks after surgery, three seeded and two unseeded control grafts were examined for prostacyclin release. In addition, thromboxane release was assessed in one seeded and one unseeded graft. Sections of aorta and graft were removed and incubated in PBS containing either 10 microM calcium ionophore A23187 or 20 microM arachidonic acid. The incubation mixture was sub-sampled at 5 min intervals over a 20 min period to assess the progressive release of prostacyclin and thromboxane A2 using a radioimmunoassay for 6-keto-prostaglandin F1 alpha and thromboxane B2 respectively. In seeded grafts, 6-keto-prostaglandin F1 alpha release averaged 15 per cent compared with aorta at 2 weeks and 45 per cent compared with aorta at 6 weeks. By contrast, release from unseeded grafts was undetectable at 2 weeks; however, by 6 weeks there was some release amounting to 15 per cent compared with aorta. There was a statistically significant increase in the release of 6-keto-prostaglandin F1 alpha from mesothelial cell seeded grafts at 6 weeks compared with unseeded grafts (P less than 0.01). Thromboxane release from the graft sections was variable and unrelated to whether the grafts had been seeded or not. These preliminary results, showing that grafts seeded with autologous peritoneal mesothelial cells release more prostacyclin than unseeded grafts, further highlight the role of the mesothelial cell as an alternative to the endothelial cell for improving the patency of arterial Dacron prostheses in the early postoperative days.

Animals↗

PubMed1991

Randomized study on the effect of collagen impregnation of knitted Dacron velour aortoiliac prostheses on blood loss during aortic reconstruction.

Intraoperative blood loss is an important factor in reconstructive surgery for aortoiliac disease because it is clearly associated with an increase in the operative morbidity and mortality rates. To minimize intraoperative blood loss, a blood-tight vascular prosthesis has been developed by impregnating a knitted Dacron prosthesis with bovine collagen. To study a potential reduction of intraoperative blood loss using these collagen-impregnated prostheses, we conducted a prospective randomized trial involving the collagen-impregnated prosthesis and its non-impregnated substrate, the Dacron knitted non-impregnated prosthesis. During a 2.5-year period, 123 consecutive patients (undergoing 81 procedures for aneurysmal disease and 43 procedures for occlusive disease) were admitted for elective aortic reconstructive surgery. Equal numbers of the two prostheses were randomly implanted. Various parameters were monitored: intraoperative blood loss before aortic cross-clamping (phase 1), during implantation of the prosthesis (phase 2) and after release of aorta cross-clamping (phase 3); the number of intraoperative and postoperative blood transfusions; and, finally, all preoperative and intraoperative factors that might contribute to intraoperative blood loss. A significant overall difference in intraoperative blood loss between the collagen-impregnated (1907 ml) and the non-impregnated (2425 ml) group was found (P = 0.003) [corrected]. However, this difference could not be attributed to collagen impregnation because no statistically significant difference in blood loss was found in the relevant period of operation (phase 3). Similar results were observed in patients operated on for both aneurysmal and occlusive disease (2600 versus 2195 ml and 2105 versus 1344 ml respectively).

Adult↗

PubMed2001

Computer-assisted implantation of total knee prostheses: a case-control comparative study with classical instrumentation.

A navigation system should improve the quality of a total knee prosthesis implantation in comparison to that obtained with the classical, surgeon-controlled operative technique. The authors implanted 30 total knee prostheses with an infrared navigation system (Orthopilot, Aesculap, Tuttlingen, Germany). The quality of implantation was studied on postoperative long-leg coronal and lateral X-rays, and compared to a control group of 30 matched-paired total knee prostheses of the same type (Search prosthesis, Aesculap, Tuttlingen, Germany) implanted with a classical, surgeon-controlled technique. An optimal mechanical femorotibial angle (177 to 183 degrees) was obtained in 25 cases in the study group and 21 cases in the control group (p > 0.05). Similar differences were seen for the coronal and sagittal orientations of both tibial and femoral components. Globally, 23 cases in the study group and 8 cases in the control group were implanted in an optimal manner for all studied criteria (p < 0.001). The navigation system used allows a significant improvement in the quality of implantation of a total knee prosthesis in comparison to that obtained with a classical, surgeon-controlled instrumentation, and long-term outcome could consequently be improved.

Aged↗

PubMed1994

Polyethylene wear debris and tissue reactions in knee as compared to hip replacement prostheses.

Differences in bearing surface conformity and wear mechanisms suggest that the polyethylene (PE) wear debris generated by total knee replacement (TKR) prostheses should be different than that in total hip replacement prostheses (THR). To address this issue, PE wear debris and the cellular response in periprosthetic tissues from 19 failed TKRs was compared to that from 24 failed THRs using polarized light microscopy and a semiquantitative grading system. The foreign-body inflammatory reaction in the THR case was characterized by plump macrophages with a diffuse cytoplasmic birefringence when examined under polarized light, indicating the presence of multiple submicron particles of PE. The majority of PE particles were less than 1 mum in size and only a small fraction of the total were greater than 10 mum. The foreign-body inflammatory reaction in the TKR cases was characterized by giant cells with fewer macrophages. In the TKR specimens, the size range of PE particles was broader than in the hips. PE particles between 2 and 20 mum were frequent in TKR specimens; particles less than 1 mum in length were less common than in the THR specimens. Diffuse cytoplasmic birefringence was not a characteristic of the TKR cases. These histologic differences were so consistently distinct that the source of the specimen (i.e., from a THR or TKR) could be blindly determined by light microscopy.(ABSTRACT TRUNCATED AT 250 WORDS)

Foreign-Body Reaction↗

PubMed2001

The wear pattern in metal-on-metal hip prostheses.

The accumulated data suggest that there is a strong correlation between polyethylene wear and osteolysis, which ultimately leads to prosthetic loosening. Second-generation metal-on-metal prostheses have been introduced, with an eye toward resolving this wear-induced osteolysis problem. The metal particles and ions are biologically active and can affect the cell homeostasis. Thus, defining the wear pattern and ratio of a given metal-on-metal prosthesis system is desirable. An early high-wear or run-in phase followed by a low-wear phase or steady state has been suggested for metal-on-metal hip prostheses. The aim of this study was to define the wear pattern of metal-on-metal bearings. The prosthesis systems were tested in a joint simulator. An early accelerated wear phase transformed to a slower wear phase after 700,000 cycles. The run-in and steady-state wear rates for combined head and liner averaged 2.22 mm(3)/Mc and 1.0 mm(3)/ million cycles, respectively. The metal-on-metal prosthesis featured a biphasic wear trend with the wear ratio in run in being more than twofold higher than the steady-state phase.

Biocompatible Materials↗

PubMed1977

Surface characteristics of the cardiac prostheses in vivo.

The pseudoneointima (PNI) deposited onto a cardiac prosthesis surface reflects many factors of biocompatibility, surface morphology, flow distribution, design, animal's physiological condition, and duration. In the evaluation of any prosthesis, the PNI is one of the prime considerations from both material and functional standpoints. Historically, Dacron fabric has been used as an internal lining for cardiac prostheses. However, we have observed cracks on the Dacron fibers, fiber fracture, fiber protrusion, and poor attachment to the diaphragm, which can cause potentially disastrous complications. In addition, there are basic differences in the PNI formation on aldehyde-treated pericardium and natural aortic valves as compared to the Dacron fabric. 1) Minimal degeneration takes place on the chemically treated natural tissue compared with the fabtic surface. Intact cells on the tissue suggest a greater compatibility. In later specimens (13 and 24 days), there is active cell infiltration onto the pericardium structure with capillary formation. 2) The deposits on natural tissue are mostly fibrin, with minimum cellular involvement and a trend toward reduction in thickness. 3) Fibroblast cells are found on the natural tissue as early as 7 days but were not observed on the Dacron fabrics. Based on these findings, the Dacron fabric-covered diaphragm studied was not favorable for use in long-term implantation of cardiac prostheses.

Adsorption↗

PubMed1984

Healing pattern of small caliber dacron grafts in the baboon: an animal model for the study of vascular prostheses.

Although dogs have been used widely to study the healing of large caliber synthetic grafts, hypercoagulability probably makes the dog a poor model for studies of small caliber vascular prostheses. The baboon's coagulation system is similar to man's, but large caliber baboon grafts were reported to endothelialize rapidly. In this study the healing pattern of 4 mm internal diameter Dacron carotid interposition grafts in baboons was determined using specimens harvested at time points between 2 weeks and 18 months post-implantation and examined with light and scanning electron microscopy. The luminal surface of baboon grafts in the acute healing phase (less than 1 month) was comparable to that reported in the literature for dogs. Baboon grafts did not completely endothelialize until 10-12 weeks post-implantation. For work with small caliber vascular prostheses, the dog appears to have no advantage over the baboon as an animal model on the basis of graft healing.

Animals↗

PubMedDate not supplied

Materials, clinical and morphological evaluation of custom-made bioreactive-glass-coated canine hip prostheses.

Bioreactive-glass-coated hip prostheses were implanted in dogs for periods of time ranging from 3 to 17 months. The prostheses were tailor-made for each animal through the use of standard radiographs. However, such a procedure does not necessarily yield a close apposition between the glass layer and bone. As a result, the initial stability of the component can be lost before bone bonding is established. Secondary to this phenomenon, the micromotion can lead to a continuous disruption of the top film on the glass despite the evidence of various reaction layers on the glass surface.

Animals↗

PubMedDate not supplied

Polyester prostheses as substitutes in the thoracic aorta of dogs. II. Evaluation of albuminated polyester grafts stored in ethanol.

In an attempt to find an alternative procedure to the preclotting of porous textile vascular prostheses, the feasibility of an albumin coating and ethanol preservation technique has been evaluated by implanting albuminated polyester prostheses as substitutes in the thoracic aorta of dogs. Nine different grafts representing woven, knitted, and velour constructions were implanted for periods ranging from 4 h to 6 months. At the sacrifice, the grafts were excized for measurement of the thrombogenicity of the flow surface, for pathological examination by light microscopy and SEM, and for quantifying the changes in the textile structure during implantation. Also the kidneys were removed and examined for infarcts caused by trapped circulating emboli. The healing characteristics of the nine different grafts proved similar and followed the same sequence of events as preclotted control grafts. The albumin coating and ethanol preservation resulted in a somewhat slower rate of healing. Yet, given sufficient time, a more completely healed graft was achieved as evidenced by the presence of endothelial-like cells throughout the length of the graft. In addition, the albumin is believed to reinforce the textile structure by reducing the tendency to stretch and dilate in vivo.

Albumins↗

PubMed1987

Textile arterial prostheses: is water permeability equivalent to porosity?

Porosity and water permeability are two distinct terms that describe different characteristics of vascular prostheses. The porosity is a measure of the void fraction within the prosthesis wall and is believed to give a rough prediction of the capacity of the graft to anchor newly formed surrounding tissue after implantation, whereas the water permeability indicates the rate at which water can flow through the prosthesis wall and, when measured under physiological pressure conditions, provides the surgeon with information about the need for preclotting prior to implantation. The literature has not always clearly distinguished between these two terms, and some authors in fact have suggested that they both refer to the same property of a prosthesis. In an attempt to clarify the issue, porosity and water permeability measurements were made on 34 commercial vascular prostheses having different textile constructions. Linear regression analysis demonstrated that these two characteristics are only weakly related (r = 0.59). It is therefore recommended that the current draft standards for such devices reference both properties: porosity and water permeability.

Blood Vessel Prosthesis↗