摘要:

AbstractPolymer composites are being recognized as important implant materials for fracture fixation plates. The use of a composite material is dependent upon the mechanical properties of the material and its biocompatibility. The primary objective of this project was to evaluate 30% chopped‐carbon‐fiber‐reinforced poly(etherether‐ ketone) (CFRPEEK) as a potential material for use as a fracture fixation plate. A two‐ phase study was conducted. The first phase analyzed the short‐term biocom‐patibility of CFRPEEK through rabbit muscle implant testing. CFRPEEK exhibited a nonspecific foreign body tissue reaction similar to the response observed with ultra‐high‐molecular‐weight polyethylene (UHMWPE). In the second phase, four‐hole CFRPEEK plates were implanted as internal fixation devices for transverse midshaft femoral osteotomies in beagles. The plates were effective in promoting fracture healing. A nonspecific foreign body reaction was observed to the plates and

ISSN:0021-9304    

DOI:10.1002/jbm.820260202

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe osteoconductive nature of calcium phosphate ceramics (CPC) follows from several proven effects, such as a direct bone attachment and enhanced bone tissue formation. Mechanisms leading to these phenomena are still largely undiscovered. Specifically, little is known about the CPC surface and cell‐driven reactions. These atomic and molecular level events are involved in tissue attachment and enhanced tissue formation. It is hypothesized that the zeta potential of these ceramics is directly related to the surface reactivity governing osteoconductivity. As a first step in our analysis, the zeta potential of stoichiometric and Ca‐deficient hydroxyapatite was determined as a function of immersion time. It is concluded that, under the conditions of the experiment, the observations support the hypothesis in a dual way. First, the absolute values of the zeta potential which were measured are related to electrokinetic potentials known to cause substantial effect on the cellular activities and bone tissue formation when applied exogenously. Second, the magnitude and duration of the changes in zeta potential are related to an ion exchange between the hydrated layer around the ceramic and the ceramic surface, and a net precipitation of new material. If these findings could be confirmed in other solutions, i.e., solutions with a substantially equivalent composition as the fluids in developing bone tissue, a basis would be provided to explain the bridging of the ceramic surface with the surrounding developing tis

ISSN:0021-9304    

DOI:10.1002/jbm.820260203

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractWe have synthesized a new family of materials we termed organoapatites which may be useful in the formulation of artificial bone. These materials are synthesized by nucleation and growth of apatite crystals in media containing poly(amino acids) or synthetic organic polyelectrolytes using strict atmospheric, temperature, and pH control. The macromolecules used to synthesize the organoapatites include poly(L‐lysine), poly(L‐glutamic acid), and poly(sodium acrylate). The products were characterized by x‐ray diffraction, scanning electron microscopy, surface area measurements, elemental analysis, and spectroscopic techniques. Organoapatites were found to contain large surface area morphologies with small crystallites which mature slowly based on analysis of Ca/P ratios. The organic macromolecules are thought to induce nucleation of crystals but also to quench their growth, thus becoming intimately dispersed in a mineral network. The organomineral particles harvested from the reaction medium contain polymernetted microcrystals, and for this reason the synthetic approach can be used to modulate crystal maturation and biological response. It is likely that the preparative approach mimics some aspects of natural bone matrix synthesis and could be specially useful in the preparation of mineral implants containing intimate dispersions of small amounts of biomolecules such as growth factors, special drugs, or bioadhe

ISSN:0021-9304    

DOI:10.1002/jbm.820260204

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe effect of biomaterials on the super‐oxide‐producing ability of neutrophils was studied. Human peripheral blood neutrophils were incubated with cobalt‐base alloy (F‐75) or polystyrene beads of nonphagocytosable size. Respiratory burst activity was studied by measuring super‐ oxide dismutase inhibitable reduction of cytochrome C. Neutrophils were found to release no more superoxide anion on incubation for up to 3 h with either material in a protein‐free medium than controls without foreign material. However, the ability of neutrophils incubated with either biomaterial to subsequently respond to phorbol myristate acetate challenge was decreased (p<0.05). Chemical analysis of supernatants for the F‐75 samples showed a high concentration of cobalt in the medium within 1 h of incubation. Minimal chromium and nickel was detected. No correlation could be demonstrated between metal in solution and the respiratory burst defect in neutrophils. Instead it appears that interaction of cells with either surface was the critical event in altering the response to phorbol myristate acetate. This observed functional defect may play an important role in rendering tissue around implanted biomaterials susceptible

ISSN:0021-9304    

DOI:10.1002/jbm.820260205

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractInfection remains a major complication following the use of implanted biomaterials. Often these infections are caused by low‐virulence organisms or by a mixture of organisms (polymicrobial). In this study two methods were used to quantitate the bacteria which had adhered to poly(methyl methacrylate) (PMMA) samples. The bacteria were eluted from the sample using an ultrasonic cleaner. The number eluted was then counted by colony counts, which determines viable organisms and by particle counting which counts both viable and nonviable organisms. A known adherent strain of Staphylococcus epidermidis and a strain of Proteus mirabilis were used. In general the adherence of S. epidermidis was greater than that of Proteus. When the two organisms were used together, there was an alteration in the adherence pattern which generally increased the adherence of Proteus and had no effect or decreased the adherence of S. epidermidis. The use of both quantitation techniques provided important information on the adherence of organisms to PMMA to which gentamicin had been added. It was evident that organisms did adhere to the PMMA plus gentamicin samples but were not viable when eluted. The amount of adherence to PMMA plus gentamicin was similar to that of PMMA alone at 30 min but was markedly decreased at 24 h. There was a considerable dead biofilm mass on the PMMA plus gentamicin samples which might be a significant promoter of late infections by providing a surface attractive to other strains of bacteri

ISSN:0021-9304    

DOI:10.1002/jbm.820260206

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractSilicon elution from bioactive ceramic powders was measured using an in uitro solubility test, in which the powders were soaked in phosphate buffer solution. Silicon elution was highest in Bioglass (BG), followed by Ceravital (KGS), apatite‐ wollastonite‐containing glass ceramics (A‐W·GC), and hydroxyapatite (HA), respectively. Silicon elutions on this in uitro solubility test were correlated with the rates of rapid death in mice following intraperitoneal injection of each of these bioactive ceramic powders. Histopathological examination of the mice revealed nephropathy, which was considered to be the cause of death. The nephropathy was characterized by epithelial degeneration in the renal tubules and increased silicon content throughout the entire kidney, findings suggesting silicon nephropathy. It is considered that, because a large quantity of silicon eluted from the powder was absorbed from the peritoneum, concentration in the glomerular filtrate and urine increased until silicon polymerization occurred, after which the silicon polymer became deposited in the renal tubules. A single injection of furosemide prevented the acute nephrotoxicity of bioactive ceramic

ISSN:0021-9304    

DOI:10.1002/jbm.820260207

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe adhesion and detachment of platelets were studied on glass coatings of a series of copolymers of hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) with preadsorbed fibrinogen. Observations of the interactions of acridine‐orange‐labeled washed platelets with these surfaces from a flowing (500 s−1wall shear rate) suspension in Tyrode's solution containing albumin and red cells were made with epifluorescent video microscopy (EVM). In some cases preadsorbed materials were incubated for 24 h, during which little or no loss of protein occurred. Protein surface concentration, by itself, was a poor indicator of expected cell adhesion and morphology. Surface chemistry was a second important factor which must be considered. A third observation is that for the 100% EMA copolymer, 24 h of incubation led to a large reduction in platelet adhesion when compared to the 100% EMA material without incubation. For the 0% and 100% EMA polymers, the percentage of contacting platelets which adhere and detach is greater for the 24‐h incubation cases than for those not incubated. These results led to the conclusion that our most hydrophilic surface favors adhesion with detachment, transient cell contact, over long‐term adhesion, as does incubation of adsorbed protein. A brief discussion is presented of a possible connection between this behavior and platelet consumption in viuo for

ISSN:0021-9304    

DOI:10.1002/jbm.820260208

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe purpose of this study was to characterize the response of articular cartilage to weight bearing against a metallic personalized hemiarthroplasty prosthesis. Ten dogs each underwent surgery in which an elastomeric replica of the left femoral patellar groove was made. Using this replica, a 0.5‐mm‐thick prosthesis was cast in Co‐Cr alloy and subsequently the surface was polished to a mirror finish which had a center line average roughness value in the range of human hemiarthroplasty implants. A second surgery was performed to resurface the left trochlea with this prosthesis. Five animals were sacrificed at 3 months and 5 at 6 months. Cartilage damage occurred primarily in the distal region of the patella, and was especially evident at 6 months. Mechanical indentation tests conducted on patellar cartilage in a saline bath at 37°C indicated both increased deformation and residual deformation in the affected areas, indicative of degenerative change. Areas of fibrillation with a depletion of proteoglycans were identified histologically. These areas were only superficial at 3 months but became more extensive at 6 months. Rheological analysis of the synovial fluid of tests joints indicated that a decrease in viscosity occurred from 3 to 6 months, an additional indicator of progressive degeneration. This novel implant model showed that even if a metallic hemiarthroplasty implant had an identical geometry as the joint surface being replaced and had a reasonably smooth surface, cartilage degeneration inevitably re

ISSN:0021-9304    

DOI:10.1002/jbm.820260209

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe interface between bioactive ceramics and bone was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The materials were apatite‐wollastonite‐containing glass ceramic (A‐W · GC) as a representative surface‐active ceramic, and calcite and p‐tricalcium phosphate (p‐TCP) as resorbable ceramics. Particles of these materials, ranging between about 100 pm and 300 pm in diameter, were implanted into rat tibiae, and specimens were prepared for observation at 8 weeks after implantation. Both SEM and TEM demonstrated that A‐W · GC was bonded t o bone through a thin Ca‐P‐rich layer consisting of fine apatite crystals apparently different from those of bone in shape, size, and orientation. Collagen fibers of the bone reached the surface of this layer, and chemical bonding between A‐W · GC and the bone was speculated. Calcite and p‐ TCP, on the other hand, made direct contact with the bone, and no apatite layer was present at the interface. The surfaces of the implants became rough due to degradation, and bone grew into the finest surface irregularities. However, we were unable to demonstrate any continuity of crystals between the resorbable implants and bone by high‐resolution TEM. Ac‐ cordingly, the bonding strength was considered to be mainly attributabl

ISSN:0021-9304    

DOI:10.1002/jbm.820260210

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820260211

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY