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  • 101
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    Journal of Applied Biomaterials 1 (1990), S. 329-329 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 102
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    Journal of Applied Biomaterials 1 (1990), S. 333-333 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 103
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    Journal of Applied Biomaterials 1 (1990), S. 331-332 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The purpose of my column is to provide readers with current information on biomaterialsrelated standards produced by both private groups and government agencies, and standards-related activities. Standards are descriptive documents given official status by their producers, and in the case of biomaterials, they are generally intended to provide formalized descriptions of (a) materials used in the construction of medical devices, (b) materials used directly in surgical repairs, (c) test methods to evaluate materials for such applications, and (d) methods for handling or processing such materials.Please consider this column not only a place to obtain biomaterials standards information, but also a place to submit news of biomaterials standards developments in order to get the information before the public. This inviation extends to members of all professional organizations and government agencies in the United States and abroad who are active in standards development and would like specific activities or standards publicized. I will present the information in this column to the extent that allotted space allows.And last, a caveat-since this is a column, it contains both factual information and opinions. I will make every effort to make it clear which is which. Also, as a frame of reference, please note that this column was written and submitted in September 1990.
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  • 104
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    Journal of Applied Biomaterials 4 (1993) 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 105
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    Journal of Applied Biomaterials 1 (1990), S. 335-338 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The patent literature can be a morass of confusion. It is complicated by legalese, often uncommunicative titles, and difficult, as well as cryptic, categorization. To keep current with the broad arena of patents on biomaterials and medical devices is much more difficult than keeping current with the scientific literature of the international journals.It is the goal of my column to provide readers with techiques and tools to better utilize this rich source of scientific information. Also, I intend to provide focused surveys of recent patents in specific areas relating to biomaterials and medical devices. Finally, I will try to include discussion of what constitutes patentable material and educate those of us who are new to patent literature and new to the requirements of applying for patents for our discoveries.I appeal to the readership to submit request for specific areas to be addressed in this column. The interaction will enrich us all.
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  • 106
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    Journal of Applied Biomaterials 2 (1991), S. 1-12 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The purpose of this study was to evaluate a biodegradable poly(L-lactide) (P—L—LA) screw for osteosynthesis under a load-bearing condition. A proximal tibial osteotomy on 25 rabbits was fixed with a biodegradable screw made of P—L—LA. A follow-up study was done at 1, 2, 4, 8, and 16 weeks. In another 25 rabbits, the tibial osteotomy was fixed with stainless steel (SUS) screws of the same size as the P—L—LA screws with a similar follow-up period. Radiographic, histological, microradiographic, and oxytetracycline-labeling studies showed healing of the osteotomy within 4 to 8 weeks. The displacement of frag-ments and the mass of newly formed bone around the screws were measured by histomorphometric analysis. There was no significant difference in the displacement of the fragments in these two groups and new bone was more abundantly detected in the P—L—LA group than in the SUS group. Histologically, no inflammatory lesion was detected in either group. All osteotomies united without delay and the displacement was minimal, although no external support was applied and the rabbits were allowed to move freely after the operation. The results of this study suggest a possible use for a P—L—LA screw in the clinical treatment of human bone fractures.
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  • 107
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    Journal of Applied Biomaterials 2 (1991), S. 13-22 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A test methodology was developed for exposing degradable polymer test specimens to a simulated chemical and mechanical body environment and then testing them periodically to detect changes in stress-strain behavior. Poly(ortho ester) specimens were exposed to cyclic loading in aerated tris-buffered saline (pH = 7.4) at 37°C. Specimens were removed at various time periods and the mechanical properties determined. To determine the effects of cyclic loading alone, additional specimens were cycled in air for the same cyclic periods and tested in the same manner. To determine the effects of a constant load on degradation rate, other specimens were subjected to a static load while exposed to trisbuffered saline. Additional specimens were subjected to immersion in tris-buffered saline without loading.Exposure to tris-buffered saline alone had a small effect on the rate of change of the mechanical properties of the poly(ortho ester) specimens while cyclic loading in air alone had no effect. However a combination of both exposure to tris-buffered saline and a static load decreased the flexural yield strength by 29% and the modulus of elasticity by 20% after 40 days, and a combination of both exposure to tris-buffered saline and cyclic loading decreased both the flexural strength and modulus by 75% after 40 days.
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  • 108
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    Journal of Applied Biomaterials 2 (1991), S. 23-28 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: As-polymerized poly(L-lactide) test rods were sterilized by seven different specially designed computer-operated autoclaving programs. As a control, common hospital sterilization was performed. In all cases, the molecular weight decreased after sterilization. A short time high-temperature sterilization lead to less molecular weight decrease than a low sterilization temperature cycle with a longer sterilization time. Regular hospital sterilization significantly reduced the elongation at break and also resulted in a decrease of 35% in tensile strength. The program causing minimal damage to the material properties was studied in detail. This program, with a steriliztioan period of 60 s and 129°C, was effective for PLLA steriliztation and also looks very promising for sterilization of other thermo- and moisture-labile polymers.
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  • 109
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    Journal of Applied Biomaterials 2 (1991), S. 37-40 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Previous studies have shown that synthetic calcium phosphate ceramics are biocompatible materials capable of providing scaffolding for new bone growth as well as osteogenesis. In particular, hydroxylapatite (HA) is less soluble than β-tricalcium phosphate (β-TCP) which has a higher degree of bioactivity. An implant made of dense hydroxylapatite shows substantially less bone growth than an implant made of a suitable HA/TCP ratio.1 Therefore, since biological response to the two materials is different, it is essential to have some means of determining the ratio of hydroxylapatite to β-tricalcium phosphate to ensure quality control of the synthetic ceramic as well as optimum biological response. In this study, a calibration curve was developed for x-ray diffractometer examination of mixtures of HA and β-TCP. The accuracy of using the diffractometer was compared to the accuracy of a powder camera, and it was determined that the diffractometer correctly identified the ratio within a range of 3% while the powder camera was accurate within a 20% range. This study showed that with an appropriate calibration curve, the HA/TCP ratio can be determined to a greater degree of accuracy using an x-ray diffractometer than by powder camera methods.
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  • 110
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    Journal of Applied Biomaterials 2 (1991), S. 29-35 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Anteior cruciate ligament (ACL) grafts made from expanded polytetrafluorethylene (ePTFE) were examined after failure (n = 7; 3 instabilities, 2 partial and 2 complete ruptures) to provide information about secondary fixation mechanisms via ingrowth of the different tissues. The ultrastructural evaluation clearly evidenced the existence of two main interface areas of ePTFE ACL-replacement: First, in areas without a dense cellular infiltrate there was interdigitating collagen producing a dense ePTFE-collagen network. Additionally, in a few areas of the graft/bone-tunnel interface a fibrous cartilage or bone regenerate could be demonstrated to be in contact with the prosthesis. Second, there was a dense infiltration of macrophages and multinuclear giant cells, partially containing birefringent material of implant origin, with and without a neosynovia-like reaction product, indicating a disturbance of tissue integration of the prosthesis. In areas of inflammation there was no bone development and only few collagen interdigitation with the graft material. This study provides further knowledge about mechanisms of secondary graft fixation due to tissue ingrowth. The interdigitation of collagen fibers and ePTFE filaments provides interfaces which should be at least partially resistant against load.
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  • 111
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    Journal of Applied Biomaterials 2 (1991), S. 55-56 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 112
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    Journal of Applied Biomaterials 2 (1991), S. 57-58 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
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  • 113
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    Journal of Applied Biomaterials 2 (1991), S. 63-65 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
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  • 114
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    Journal of Applied Biomaterials 2 (1991), S. 61-62 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
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  • 115
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    Journal of Applied Biomaterials 2 (1991) 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
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  • 116
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Numerous carrier systems have been developed for the controlled delivery of biologically active molecules such as drugs and diagnostic agents. The biophysical interactions between the biologically active molecules and their carriers, however, may denature the former and lead to reduced biological activity. In this study, a model nondenaturing carrier comprised of a nanocrystalline (10-7 m) tin oxide core and a surface-charge-reducing organic bonding layer (GF292) was synthesized. A subsequently bound protein (human transferrin) showed significant retained conformation by immunoelectron microscopy. In the synthesis of targeted drug systems and vaccines, nanocrystalline cores treated with appropriate surface-modifying agents may be suitable carriers.
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  • 117
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    Journal of Applied Biomaterials 4 (1993), S. 13-27 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study focuses on examining the biological response of intramedullary bone to poly-L-lactic acid (PLLA), particularly during the PLLA degradation phase. To study the influence of spherical crystals (spherulites) of PLLA on intramedullary bone response, two different types of PLLA coupon, with and without spherulites but with the same molecular weight, were used. Chambers containing PLLA coupons were implanted into the right femur of eight dogs, four with and four without spherulites; chambers containing stainless steel (SS) coupons (as a control) were implanted in the left femurs of all eight. Two dogs, one with and one without spherulites, were sacrificed at 3, 6, 12, and 24 weeks postoperatively. Histomorphometric evaluation and histophathological assessment were used to compare the response to PLLA and SS. Scanning electron micrographs showed that there were minimal changes in the surface of PLLA coupons at 3 and 6 weeks. But at 12 and 24 weeks, there were many cracks and holes on the surfaces of the coupons, and some parts of the surface were scaling off. The cross-sectional area of PLLA coupons showed no change at 3 and 6 weeks, but started to decrease by 12 weeks. The amount of ingrown bone between PLLA coupons was significantly greater than that between SS coupons at 3 and 6 weeks, but had decreased dramatically by 12 weeks. Extensive bone resorption around PLLA coupons occurred by 12 weeks accompanied by infiltration of inflammatory cells. An abundance of histiocytes, giant cells, and leucocytes were seen, along with a few histiocytes that had phagocytized PLLA particles of less than 2 μm. By contrast, no inflammatory reaction was seen in SS samples at any period up to and including 24 weeks. PLLA demonstrated excellent biocompatibility with intramedullary bone for the first 6 weeks in this model. Once degradation commenced, however, biocompatibility decreased dramatically. Our study detected no difference between coupons with and without spherulites. It thus appears that the existence of relatively large PLLA particles did not influence the response of intramedullary bone to PLLA, but rather that it was the smaller particles (〈 2 μm) released from the PLLA that induced foreign-body inflammatory reactions and bone resorption. It is also possible that a local decrease in pH occurred around PLLA coupons, which could have influenced vital kinetics. © 1993 John Wiley & Sons, Inc.
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  • 118
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    Journal of Applied Biomaterials 4 (1993), S. 39-46 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An in vivo investigation of a new high molybdenum and nitrogen duplex stainless steel (25Cr—7Ni—4Mo—0.3N) has been performed. Cylindrical pins and specially developed devices, to test in static conditions the in vivo localized corrosion resistance, made of this new duplex steel and of a common austenitic stainless steel were implanted in rabbit's femurs for 6 and 12 months. After sacrifice, SEM observations and EDS microanalyses to detect metallic ion release were carried out on the femur sections surrounding the pins. Morphologic observations with stereoscope and SEM were performed on the metallic surfaces of the special devices in order to detect the presence of localized corrosion. Both ion release and localized corrosion were observed for the specimens made of austentic stainless steel, but not for those made of 25Cr—7Ni—4Mo—0.3N duplex stainless steel. © 1993 John Wiley & Sons, Inc.
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  • 119
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    Journal of Applied Biomaterials 4 (1993), S. 47-54 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The static general corrosion behavior of Ti-6Al-4V alloy specimens in three lactated Ringer's-based solutions was investigated using d.c. potentiodynamic, d.c. linear polarization resistance, and a.c. impedance techniques. A critical appraisal of the use of these techniques for the estimation of the corrosion rate of the material is presented. Whence it was shown that the presence of bovine serum in or decreasing the pH level of (to about 1) lactated Ringer's solution leads to an increase in the corrosion rate of the alloy (relative to that in lactated Ringer's solution, pH 6.25). © 1993 John Wiley ' Sons, Inc.
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  • 120
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    Journal of Applied Biomaterials 2 (1991), S. 127-131 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: National population-based estimates on the magnitude and distribution of orthopedic implant devices in the United States have not been available to date. The Food and Drug Administration's Center for Devices and Radiological Health (FDA/CDRH) collaborated with the Centers for Disease Control's National Center for Health Statistics (CDC/NCHS) in the design and conduct of a nationwide medical device implant survey to generate the first national population-based prevalence estimates of orthopedic implant devices. A Medical Device Implant Supplement to the 1988 National Health Interview Survey was administered in personal household interviews to a national sample of 47,485 households, which included 122,310 individuals.An estimated 6.5 million orthopedic implants were in use in the general US population in 1988, including 1.6 million artificial joints and 4.9 million fixation devices. As a group, orthopedic implants comprised nearly half of all medical device implants in use, 43.4%. The majority of artificial joint recipients were 65 years of age or older, white, and male. the majority of fixation device recipients were less than 45 years of age, white, and male. The limitations and strengths of these population-based estimates are discussed.
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  • 121
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    Journal of Applied Biomaterials 2 (1991), S. 133-139 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The field of biomaterials has grown rapidly over the last three decades in the academic, industrial, and regulatory sectors. Beginning as a research thrust, which led to courses at a few universities, biomaterials education has evolved into distinct curriculum in over 60 institutions in the United States and Canada alone.Rapid growth, however, can cause problems. In an effort to determine the present status and future needs in each sector, as well as begin to assess if the needs of industry are being met by present academic programs, two surveys were sent out.As shown by the two surveys, academic programs have been increasing in both size and quality while industry has also been expanding, as indicated by the many small companies involved in biomaterials. The shift toward graduate programs is in keeping with the perceived educational needs of potential employers. The majority of academic programs appear to be providing the training and coursework desired by employers. Further information, however, is needed to determine if the number of graduates trained in biomaterials is adequate, or in fact excessive.It is, therefore, recommended that a more comprehensive survey, sent to the biomaterials companies listed in the FDA registry, be undertaken. In addition, a survey to each academic program that addresses hiring of recent graduates would also be beneficial. It does appear that certain standards for curricula could be agreed upon, although the field has probably not evolved sufficiently for accreditation or professional registration to be addressed yet.
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  • 122
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    Journal of Applied Biomaterials 1 (1990), S. 3-12 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Porous coated Ti-6Al-4V has a high-cycle fatigue strength that is approximately one-third the strength of the uncoated material. Stress concentrations at the interface between the porous coating and the substrate contribute to this fatigue strength reduction. Modification of the interfacial geometry may reduce the severity of the stress concentrations. The interface between the porous coating and substrate was modeled using two-dimensional finite element analysis. This analysis identified geometric parameters that affect the value of the stress concentration factor, Kt. The effect of five geometric parameters onKt was determined: contact area between porous coating and substrate (CA), sinterneck radius (r), porous coating particle radius (R), interparticle distance (d), and interparticle sintering. Increased contact areas, decreased sinterneck radii, and decreased interparticle distances increased Kt, while porous coating particle size had a small effect on Kt. Sintering between neighboring porous coating particles increased Kt at the outermost sinternecks, but decreased Kt at inner sinternecks. The results can help predict how varying these coating parameters can reduce stress concentrations in a porous coated material.
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  • 123
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 124
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 125
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    Journal of Applied Biomaterials 4 (1993), S. 103-105 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 126
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Two new cardiovascular monofilament sutures attached to taper point needles have been developed for use in expanded polytetrafluoroethylene (PTFE) grafts. One monofilament suture made of PTFE has a microporous structure that allows it to be channel swaged to a needle that closely approximates its suture diameter. The other suture is a monofilament polypropylene suture that has been extruded to produce a tapered swage end, which was significantly smaller than that of the remainder of the suture in order to be channel swaged to smaller diameter needles. On the basis of comprehensive biomechanical performances, the performance of the new needle suture products with needle/suture diameter ratios approaching 1:1 was superior to needle suture products with 2:1 needle/suture diameter ratios for use in PTFE vascular grafts, regardless of the suture material. © 1993 John Wiley & Sons, Inc.
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  • 127
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    Journal of Applied Biomaterials 4 (1993), S. 109-111 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 128
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    Journal of Applied Biomaterials 4 (1993), S. 97-101 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study evaluated the biocompatibility of an unfilled, fluoride-releasing acrylic resin by subcutaneous implantation in guinea pigs. The experimental fluoride resin was compared to a nonfluoride, dental pit and fissure sealant (DELTON) of similar composition. Thirty-four male albino guinea pigs received four Teflon® tubes each, implanted in the dorsal area. The tubes were open at both ends, three contained the experimental fluoride resin and one held the nonfluoride resin. The tubes and surrounding tissue were excised in 1-2 cm blocks, by necropsy, at 14 and 84 days. Histological evaluation showed that inflammatory response was none-to-slight at 14 days for 95% of the fluoride and 100% of the nonfluoride specimens. Five percent of the fluoride specimens produced a moderate tissue response. At 84 days, inflammatory response was none-to-slight for 82.5% of the fluoride and 61.5% of the commercial nonfluoride specimens, while 17.5% of the fluoride and 38.5% of the nonfluoride specimens produced moderate tissue responses. Chi-squared analysis and Fisher's Exact test revealed no statistically significant difference (p ≤ 0.05) in tissue response between the two resins at either 14 or 84 days. Hence it is concluded that the experimental, fluoride-releasing resin produces a very mild subcutaneous tissue response and that its biocompatibility is comparable to that of a widely used nonfluoride dental resin. It can, therefore, be considered as having a high potential for biological safety as a dental restorative resin or adhesive, or for other biomedical applications. © 1993 John Wiley & Sons, Inc.
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  • 129
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    Journal of Applied Biomaterials 1 (1990), S. 91-92 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
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  • 130
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    Journal of Applied Biomaterials 1 (1990), S. 79-90 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Calcium phosphate materials are being extensively investigated for orthopaedic and dental applications. Bone grafts and bone substitutes are being developed using many forms of these materials. Numerous medical devices are being coated with them. Because of the many forms that calcium phosphate materials take, characterization of the material under investigation is essential. Aworkshop sponsored by the Society For Biomaterials on characterization of calcium phosphate materials was held on June 14 and 15, 1989. Sessions discussing the historical development, in vitro characterization, in vitro coating characterization, in vivo coating characterization, the FDA perspective, and the manufacturers perspective were held. A summary of the workshop with references is presented.
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  • 131
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    Journal of Applied Biomaterials 1 (1990), S. 95-97 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 132
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    Journal of Applied Biomaterials 1 (1990), S. 93-94 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The purpose of my column is to provide readers with current information on biomaterialsrelated standards produced by both private groups and government agencies, and standardsrelated activities. Standards are descriptive documents given official status by their producers, and in the case of biomaterials, they are generally intended to provide formalized descriptions of (a) materials used in the construction of medical devices, (b) materials used directly in surgical repairs, (c) test methods to evaluate materials for such applications, and (d) methods for handling or processing such materials.Please consider this column not only a place to obtain biomaterials standards informations but also a place to submit news of biomaterials standards developments in order to get the information before the public. This invitation extends to all members of any and all professional organizations and government agencies in the United States and abroad who are active in standards development and would like specific activities or standards publicized. I will present the information in this column to the extent that allotted space allows.And last, a caveat - since this is a column, it contains both factual information and opinions. I will make every effort to make it clear which is which. Also, as a frame of reference, please note that this column was written and submitted in November 1989.
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    Journal of Applied Biomaterials 1 (1990), S. 57-78 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The mechanical properties of biodegradable polymers and composites proposed for use in internal fixation (in place of stainless steel) are crucial to the performance of devices made from them for support of healing bone. To assess the reported range of properties and degradation rates. we searched and reviewed papers and abstracts published in English from 1980 through 1988. Mechanical property data were found for poly(lactic acid), poly (glycolic acid), poly(∊-caprolactone), polydioxanone, poly(ortho ester), poly(ethylene oxide), and/or their copolymers. Reports of composites based on several of these materials, reinforced with nondegradable and degradable fibers, were also found. The largest group of studies involved poly(lactic acid). Mechanical test methods varied widely, and studies of the degradation of mechanical properties were performed under a variety of conditions, mostly in vitro rather than in vivo.Compared to annealed stainless steel, unreinforced biodegradable polymers were initially up to 36% as strong in tension and 54% in bending, but only about 3% as stiff in either test mode. With fiber reinforcement, reported highest initial strengths exceeded that of stainless steel. Stiffness reached 62% of stainless steel wiht nondegradable carbon fibers, 15% with degradable inorganic fibers, but only 5% with degradable polymeric fibers.The slowest-degrading unreinforced biodegradable polymers were poly(L-lactic acid) and poly(ortho ester). Biodegradable composites with carbon or inorganic fibers generally lost strength rapidly, with a slower loss of stiffness, suggesting the difficulty of fiber-matrix coupling in these system. The strength of composites reinforced wiht (lower modulus) degradable polymeric fibers decreased more slowly.Low implant stiffness might be expected to allow too much bone motion for satisfactory healing. However, unreinforced or degradable polymeric fiber reinforced materials have been used successfully clinically. The key has been careful selection of applications, plus use of designs and fixation methods distinctly different from those appropriate for stainless steel devices.
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    Journal of Applied Biomaterials 1 (1990) 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
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  • 135
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A quantitative method of reporting surface degradation of the ultra-high molecular weight polyethylene (UHMWPE) tibial component from retrieved total knee replacements (TKR) was developed. Specific features include a qualitative assessment expressing the patterns in which the damage was detected as well as a quantitative summary of the observed degradation mechanisms. In addition, a method of measuring lower limb alignment changes with time is described and related to the observed damage patterns. Two case studies are presented. One case illustrated that changes in alignment resulted from factors other than wear. The damage observed on the tibial plateau appeared to occur subsequent to the changes in alignment. The second case illustrated that the wear of the UHMWPE tibial insert lead to the changes in the overall lower limb alignment. The methods described provide additional information regarding TKR failure mechanisms compared to reporting methods currently available. In particular, the collection of temporal alignment data at clinical follow-up visits enhanced the assessment of the retrieved TKR. © 1995 John Wiley & Sons, Inc.
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  • 136
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The purpose of this study was to determine whether small, phagocytosable particles of titanium alloy (Ti) and high-density polyethylene (HDPE) have an adverse effect on bone ingrowth. The bone harvest chamber (BHC) was implanted bilaterally in the proximal tibial metaphysis of six mature rabbits. The BHC has a transverse 1-mm wide pore providing a continuous canal through the chamber for tissue ingrowth. After an initial 6-week period for osseointegration of the BHC, the contents of the canal were harvested repeatedly at 3 weekly intervals. This could be done with the chamber in place, without disturbing its exterior surface or the surrounding bone. The carrier solution, 1% sodium hyaluronate (Healon) was implanted first. In subsequent implantations, Healon was mixed with particles of HDPE or Ti averaging 4.7 ± 2.1 and 3.0 ± 2.6 μm, respectively. The contralateral chamber was left empty and served as a control. The chambers were harvested repeatedly, alternating experimental and control sides. The sections from the control side, and those containing Healon alone demonstrated extensive trabecular bone in a fibrovascular stroma. The sections containing Ti alloy particles were qualitatively and quantitatively similar to the control sections and those containing Healon, except for the presence of small black granules of Ti alloy, dispersed in the fibrovascular stroma or phagocytosed by scattered macrophages. The sections containing HDPE particles were infiltrated and engulfed by mononuclear and multinuclear histiocytic cells in a highly fibrous stroma. The majority of the multinucleated cells present were interpreted as being foreign body giant cells. Less trabecular bone was seen in the HDPE group compared to the other groups. Using the parameters chosen for this experiment, it would appear that small, phagocytosable HDPE particles are more deleterious to net formation of bone compared to particles of Ti alloy. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 55-64 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study deals with a three-point flexure test for the metal-ceramic bond involving geometrically simple specimens (alloy strips partly coated with ceramic) that can be fabricated with reasonable expenditure and sufficient reproducibility. The calculation of the stress distribution in such specimens with the aid of the finite-element method (FEM) is presented. The aim of this numerical analysis is: to investigate the stress distribution in a ceramometallic specimen with dimensions that, in a large number of experiments, have proven to lead to debonding at one end of the ceramic veneer instead of a crack in the middle of the veneer; and to assign a bond strength to the measured critical bending force that takes into account the influence of the Young's modulus of the alloy as well as a possible deviation of the thickness of the metal substrate from the standard value. Bond strength values of a variety of metal-ceramic combinations are demonstrated. These experimental results demonstrate the reproducibility of the test method as well as its sensitivity to diverse parameters. The presented method is proposed as an alternative to another flexure bond test nominated for international standard. In this test ceramometallic strips are bent over a rod to a 90° angle of the specimen ends, subsequently flattened, and the fracture surface visually inspected for adherence of the ceramic to the alloy substrate along the predominant part of the middle third of the specimen. It is clear that such a test can at most deliver qualitative results. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 87-87 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 139
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    Journal of Applied Biomaterials 6 (1995), S. 105-108 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Four different brands of bone cement (Palacos R, Simplex P, Sulfix, CMW 1) were tested for exothermic changes during polymerization at atmospheric pressure and under partial vacuum of 0.2 bar. Palacos R was also mixed at four pressure levels (1.0, 0.2, 0.12, and 0.05 bar). The peak temperature in the bone cement was 46 to 124 °C, depending on the measuring point. There was no difference in peak temperature or duration of temperature increase above 50 °C during the curing of cement whether mixed at atmospheric pressure or under partial vacuum at different pressure levels. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 99-104 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A major problem in fracture treatment by external fixation is screw loosening, which often results in reduced stability and can lead to prolonged treatment. A load-carrying experiment was conducted to determine whether coating implants with bioactive hyroxyapatite (HA) increases screw stability. Twelve HA-coated ASIF screws with 3 different macroporosities were inserted in 12 sheep that had already been fitted with a 6-pin external fixator for the treatment of a tibial osteotomy. The same number of uncoated polished steel screws served as controls. Although initial stability was not different for HA-coated screws, average removal torque after a 9-week implantation period increased with increasing macroporosity of the HA coating (p 〈.002). Instability of some screws was accompanied by histologic findings of cartilagenous tissue and proliferation of periosteal callus. Near the threads in the tibial cortex and in the shaft area of the screw were seen large numbers of HA particles that had been sheared off during implantation as well as during screw removal because of high contract forces between the HA coating and bone. Particulate debris of HA particles as well as the release of small bone fragments during explantation is likely to be unavoidable since HA adherence to bone is greater than adherence to steel after several weeks of implantation. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 125-128 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Porous polyurethane foams were prepared from Daro foam components with a range of mechanical properties to simulate human trabecular bone. Ratios of 10.0:5.0, 10.0:7.9, and 10.0:10.0 isocyanate to resin were mixed, cured, and cut into cubes. Properties were determined from uniaxial compression to 50% of the original cube height at a strain rate of 1.2 mm/s. Electron microscopy was used to characterize the foam structure. Average compressive yield stress values, ultimate compressive stresses, and elastic moduli ranged from 4.44 to 2.79, 5.61 to 3.28, and 134.0 to 110.1 MPa, respectively, for the three formulations. The foam materials showed a similar morphology of spherical bubbles, and the average bubble size tended to decrease as the ratio of isocyanate to resin increased even though the bubble size differences were not statistically significant. The results indicate that large blocks of foam can be prepared with consistent mechanical properties simulating a range of trabecular bone properties so that implants can be tested for various patient populations. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 129-135 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bioabsorbable films show promise in preventing postoperative interfacial tissue adhesion. Absorbable polymers in film form are generally more sensitive to chemical environments, due to their large surface area to volume ratio. The in vivo environment contains lipids such as cholesterol, triglycerides, and phospholipids, which are known to affect the degradation of permanent and absorbable polymeric biomateials. Preliminary investigations of in vitro lipid exposure of bioabsorbable poly(ortho ester) (POE) films for implant use are described. POE has been studied previously for use in controlled drug delivery and fracture fixation. Six-week in vitro exposure of 65:35 POE films to a cholesterol emulsion (1 g/L) showed no apparent difference in hydrolytic degradation rates of mechanical properties or mass loss compared to deionized water exposed films. Decreases of 28 and 6% in inherent viscosity were observed after 5 weeks for cholesterol and deionized water exposed films, respectively, suggesting cholesterol may have some effect. Further examination of the data, due to sample variation, revealed that clear, uniform films showed only minor changes in mass loss and mechanical properties after 6 weeks in either of the in vitro media. But slightly cloudy films possessing microscopic bubbles showed accelerated degradation in both media, indicating the effect of cholesterol was inconclusive due to sample variation. Control of the microbubble formation process could have utility in controlling hydrolytic degradation of POE films. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 171-174 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Grit blasting is a common procedure of roughening surfaces to promote physical attachment of porous coatings, but it has been shown to reduce fatigue strength. Shot peening is known to increase fatigue strength by inducing compressive surface stresses; however, it is not known how subsequent grit blasting affects these benefits. This study examines the endurance limits, Se, of ELI grade Ti-6A1-4V specimens under rotating cyclic bending, including polished (control); belted and beaded; belted, beaded, and grit blasted; and belted, beaded, shot peened, and grit blasted. Belting and beading resulted in a slight increase in Se; grit blasting caused a 15% reduction in Se from polished. Fifty percent of this reduction was recovered when shot peening preceded grit blasting, suggesting that residual compressive surface stresses, induced by peening, were not eliminated by the blast process. Roughness averages and RMS values did not correlate with Se trends. SEM results showed classical fatigue fractures, consistent with surface crack initiation. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 175-183 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Concentrated fibrinogen was prepared from whole blood by cryoprecipitation or chemical precipitation and combined with thrombin to make fibrin glue (FG). Surgical application of FG include control of bleeding, adhesion of tissues, and sealing of tissue defects. The purpose of this study was to compare cryoprecipitation (cryo) of fibrinogen to precipitation using ethanol, ammonium sulfate (AS), and poly(ethylene glycol) (PEG). Our results suggest that AS precipitation is as effective as cryo in yielding fibrin glues with high bond strengths and is more effective than ethanol and PEG precipitation. In addition, the volume of FG per milliliter of plasma is greater after AS precipitation than after a single freeze-thaw cycle. It is concluded that AS is an efficient means for preparing FG from autologous blood. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 185-190 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biological materials have been used as prosthetic devices such as heart valves, vascular grafts, and pericardial patches. These biological materials have to be fixed with crosslinking reagents and sterilized subsequently before they can be implanted in humans. Recently, a new crosslinking reagent, epoxy compound, has been used to fix bioprostheses. In this fixation technique, heparin may be ionically bound on the tissue surface. It has been shown that the amount of heparin bound to the tissue surface is proportional to the quantity of protamine impregnated in the biological tissues. However, it is not known if the impregnation of protamine will affect the crosslinking density of the biological tissues. This study was designed to compare the crosslinking densities of the epoxy compound fixed biological tissues with or without heparinization. Fresh porcine aortic valves procured from a slaughter house were first impregnated in various concentrations of protamine sulfate (0, 0.5, 1.0, or 1.5%) for about 30 min. The porcine aortic valves were then crosslinked in a 4% epoxy compound solution (Denacol® EX-313). The porcine samples were taken out at various elapsed fixation periods: 18, 25, 48, 72, 96, and 120 h. Finally, the crosslinked porcine aortic valves were heparinized in a 0.5% sodium heparin solution for about 1 h. The crosslinking densities of the porcine leaflet and the aortic wall of each sample were determined by measuring their shrinkage temperatures. It was revealed that the impregnation of various concentrations of protamine did not seem to significantly alter the shrinkage temperatures of the porcine leaflet and the aortic wall throughout the entire fixation process (p 〉 0.05). This indicated that the impregnation of protamine did not significantly change the crosslinking density of the biological tissues. However, it was found that protamine tended to discolor the tissue and to stiffen the porcine leaflet and the aortic wall. Although the impregnation of protamine did not seem to significantly alter the crosslinking density of the epoxy compound fixed biological tissues, the increase of the stiffness of the heparinized tissues may cause concerns in some clinical applications. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 209-211 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Reducing the porosity of bone cement substantially strengthens the cement in fatigue. However, concern has been raised that reducing the porosity of the cement would increase the shrinkage of the cement and thus compromise the cement-bone interface. We measured diametral shrinkage of cement mantles prepared with and without centrifugation of the cement. Four cement preparations (centrifuged and uncentrifuged mixed with monomer at either room temperature or 0°C) were used to form cement mantles of four different thicknesses (2, 4, 6, and 8 mm) around a stainless steel rod. We conclude that porosity reduction dramatically increases the fatigue strength of bone cement without substantially changing the diametral dimensions of the polymerized cement when studied in the shape and volume of a cement mantle that would be used for total hip replacement. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 6 (1995), S. 225-230 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The distal migration of polyethylene wear debris appears to be a major cause of loosening and osteolysis of cementless total hip arthroplasties. The use of modern cementing techniques, circumferential porous or hydroxyapatite (HA) coating has been advocated as a means of preventing access of the particles to the bone-implant interface. The purpose of this study was to compare the ability of different methods of implant fixation to prevent wear debris migration. Three each of smooth, porous-coated, HA-coated, and cemented hemiarthroplasties were implanted in the right hip of 12 dogs. Polyethylene particles were injected into the hip once a month for 4 months and then the femurs were sectioned. The percentage bone ingrowth was 8% for the smooth, 38% for the porous, and 83% for the HA-coated sections. Infiltration of the interface membrane by histiocytes containing polyethylene particles, and endosteal scalloping or osteolysis were found on all sections of the smooth prostheses. No particles or osteolysis were found on any sections of the other three types of prostheses. Capsular and lymph node sections from all dogs revealed histiocytic infiltration with numerous polyethylene particles present. It is concluded that the use of cement, porous, or HA coating prevents or delays access of the polyethylene wear debris to the bone-implant interface. No one of these methods of fixation proved more advantageous in the 5-month limit of this study. © 1995 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 3 (1992), S. 245-249 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Extensive acetabular defects produced surgically in 25 dogs were repaired using A - W glass-ceramic blocks. No dislocation of the femoral head, and no displacement or breakdown of the blocks was seen 1 year after surgery. All dogs were able to run normally shortly after surgery, except for one that limped for a short time. The failure load between the blocks and the bone had increased markedly 2 months after implantation. The failure load/unit area was 33.2 kgw/cm2 1 year after implantation. We conclude that glass-ceramic supplementation of the acetabulum is successful experimentally, and that this may be a promising method for repair of large acetabular bone defects. © 1992 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 3 (1992), S. 251-258 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Osteochondral defects in the rabbit knee were filled with a TCP-collagen mixture. In the femoral condyles a fibrous tissue was formed in the defects similar to that seen in control defects. In the tibial plateau defects were made with penetration of the underlying epiphysis. Repair tissue was formed resembling articular cartilage. © 1992 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 3 (1992), S. 269-273 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Medicine , Technology
    Notes: Hydroxyapatite (HAP) has been used in orthopedics as an aid in bone grafts following surgery of bone tumors and osteoarthrosis, often promoting osteoconduction. The incorporation of antibiotics into HAP beads to prevent local infection would seem to be therapeutically effective. This report describes in vitro and in vivo release rate of cefotiam hydrochloride (CTM, 3.5 mg/bead) loaded into HAP beads (8.48 mm in diameter). Egg phosphatidylcholine (EPC) was also incorporated into HAP to control the rate of release of CTM. In vitro, 100% of CTM was released within 3 h from the EPC-free HAP beads. The rate of diffusion of CTM from HAP was prlonged with the incorporation of EPC. In vivo, 100% of CTM of the EPC-free CTM was released within 7 h but the rate of release of CTM from the EPC-CTM was extended. In vivo, the serum level of CTM reflected the rate of release of the antibiotics from the HAP bead. We conclude that EPC is useful in controlling the diffusion rate of CTM from HAP. © 1992 John Wiley & Sons, Inc.
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    Notes: Rats with experimental osteopenia, which was induced by resecting both ovaries and sciatic nerves (OVX + NX), were used to evaluate osteoconduction of an apatite and wollastonite-containing glass-ceramic (designated A-W.GC) and an alumina ceramic. The bone mineral densities (BMDs) of the femurs were measured by dural energy X-ray absorptiometry (DEXA) and determination of the ash weight. Twelve weeks after the first operation, when the BMDs in the OVX + NX groups were about 20% less than that in the sham-treated groups (Sham), the bioceramics were implanted into the proximal tibiae. The bone mineral masses around the implants in the proximal tibiae were evaluated by histological examination of undecalcified specimens and DEXA. Both types of implants in the OVX + NX groups showed less reactive bone than those in the Sham groups. However, a histomorphological study revealed that the direct contact area between bone and implant was larger with bioactive ceramic A-W.GC than with the bioinert alumina ceramic even under osteopenic conditions while two types of ceramic made no difference on the bone at distance from the implant. The direct contact area with A-W.GC did not show any difference between the Sham and the osteopenic OVX + NX groups. The bioactive ceramic A-W.GC appears to have good osteoconductivity solely on its surface even under osteopenic conditions.
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    Journal of Applied Biomaterials 3 (1992), S. 275-279 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An investigation of the surface by XPS photoelectron spectroscopy has shown that the process of production of cast contact lenses based on poly(2-hydroxyethyl methacrylateco-diethyleneglycol methacrylate) is accompanied by mass transfer at the lens-mold boundary. This phenomenon, which impairs the compatibility of the lens during its application, can be considerably suppressed by employing a suitable surface modification of polypropylene molds. The surface treatment consisting in the oxidation of the mold surface by an AC corona discharge in the oxygen atmosphere increased hydrophilicity of the material, thus facilitating separation of the lens from the mold. The results of the XPS study were also confirmed microscopically by employing the SEM method. © 1992 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 3 (1992), S. 313-313 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Applied Biomaterials 3 (1992), S. 281-286 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Alginate beads for immunoisolation of pancreatic islets by microencapsulation should be small, smooth, and spherical in order to ensure that around the islets a strong alginate-polylysine-alginate capsule will be formed with optimal biocompatibility and diffusion of nutrients and hormones. However, the preparation of small capsules around islets is difficult. Our newly designed air jet droplet generator allows for variations in the length and diameter of the alginate nozzle and the air jacket and is in this way adaptable to a required bead size. Alginate droplets are converted into rigid beads in a 100 mM CaCl2 solution. Their size depends upon the diameter of the jacket, the air flow rate, and the outer diameter of the nozzle, whereas the production rate depends upon the pressure on the alginate, and on the diameter and the length of the nozzle. When the air flow or the alginate flow surpasses a certain rate, the droplets are fragmented. Thus study describes the mutual relationship of these variables and defines their optimal range for reproducible production of smooth and spherical beads for microencapsulation of islets at an acceptable production rate. © 1992 John Wiley & Sons, Inc.
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    Notes: Thrombosis remains a significant and potentially catastrophic complication of polyethylene terephthalate (Dacron) prosthetic vascular graft implantation. Numerous attempts have been made to create a novel surface that reduces the adverse effects of blood interaction with the material. The purpose of this study was to create reactive groups on Dacron without significantly altering the chemical and physical properties of the biomaterial. These groups would then serve as “anchor sites” for covalent attachment of the blood protein albumin to the surface, thus creating a more biocompatible surface. Denier reduction, an established textile chemistry procedure that creates carboxyl groups on the fiber surface via hydrolysis of the material, was performed at 100°C using sodium hydroxide concentrations of 0.5, 1.0, 2.5, and 5.0% (treated materials referred to as 0.5% hydrolyzed etc.). Tensile strength determination of hydrolyzed materials revealed no statistically significant difference in material strength between control, 0.5, and 1.0% hydrolyzed materials; the 2.5 and 5.0% hydrolyzed materials had significant strength loss as compared to the controls. Significant fiber weight loss occurred in the 1.0, 2.5, and 5.0% hydrolyzed Dacron segments. The 0.5% hydrolyzed material did not have any significant weight loss. Covalent linkage of 125I-albumin to these modified materials using the crosslinker 1-ethyl-3-(3-dimethyl aminopropyl)-carbodiimide hydrochloride (EDC) resulted in the 0.5% hydrolyzed material having the greatest protein binding (330 ng/mg Dacron, 2.4-fold greater than control). Incubation of the 0.5% hydrolyzed material with EDC and various concentrations of 125I-albumin resulted in the 14.80 m̈M solution permitting the greatest binding per milligram Dacron (330 ng/mg Dacron). Scanning electron microscopy, performed blindly, revealed no change in the 0.5% hydrolyzed Dacron as compared to untreated Dacron. The 5.0% hydrolyzed Dacron, however, had noticeable structural damage on the outer periphery of the fiber surface. Observation of the untreated Dacron with nonspecifically bound albumin showed scattered areas of albumin adherent to the fiber surface whereas covalent linkage of albumin to the 0.5% hydrolyzed Dacron via EDC crosslinking showed numerous albumin moieties on each fiber. This study demonstrates that a clinically accepted biomaterial (Dacron) can be chemically modified, without significantly altering the physical and chemical characteristics of the biomaterial, in order to covalently bind albumin to the fiber surface. Thus, these results serve as foundation for creating potential novel biomaterials without significantly altering the properties of the original biomaterial. © 1995 John Wiley & Sons, Inc.
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  • 157
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    Journal of Applied Biomaterials 6 (1995), S. 19-26 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The use of multiple-component systems in orthopedic surgery gives the surgeon increased flexibility in choosing the optimal implant, but introduces the possibility of interfacial corrosion. Such corrosion could limit the longevity of prostheses due either to tissue reactions to corrosion products, or to device failure. The incidence and nature of corrosion of modular total hips was evaluated in a consecutive series of 79 retrieved implants from University Hospitals of Cleveland. Surfaces were examined with stereo- and scanning electron microscopy. Several laboratory studies were undertaken to examine mechanisms that might contribute to the initiation of corrosion. The first set of experiments investigated the effect of head neck extension; the second study looked at the effect of material combinations on fretting corrosion and crevice corrosion. Analysis of retrieved implants demonstrated that fretting corrosion played a major role in the initiation of interface corrosion, and that a correlation existed between corrosion and length of neck extensions. Laboratory studies showed that longer head neck extensions may be more susceptible to fretting corrosion because of an instability at the interface. Short-term mixedmetal corrosion studies demonstrated that the coupling of cobalt and titanium alloys did not render the interface more susceptible to corrosion. It is hypothesized that fretting corrosion contributes to the initiation of modular interface corrosion, and that the problem can be reduced by design changes that increase the stability of the interface. © 1995 John Wiley & Sons, Inc.
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  • 158
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    Journal of Applied Biomaterials 6 (1995), S. 35-41 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In ligament replacement cases where the artificial ligament has worn and partially or totally ruptured, the released wear particles have been associated with a chronic synovitis that inhibits integration of the ligament and contributes to the ultimate failure of the device. In this study, the biological response to ligament wear particles from nine different artificial ligaments was quantitatively evaluated in vivo. Wear particles, the majority of which were 〈7 μm, were generated in vitro. These particles were injected into rabbit knee joints, and the biological response as well as the systemic migration of the particles were evaluated histologically after 4 weeks. The extent of the inflammatory reaction to the ligament wear particles was found to be significantly (p 〈 0.05) influenced by the type of material implanted. No particles were found in the regional lymph nodes or in the spleen, liver, kidney, or lung. © 1995 John Wiley & Sons, Inc.
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  • 159
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    Journal of Applied Biomaterials 6 (1995), S. 43-53 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Two experimental methods for restoring flexor tendon sheath integrity and preventing adhesions around traumatized flexor tendons utilizing artificial tendon sheaths made of either hydroxyapatite (HAp) or alumina were studied in a flexor tendon-trauma model and compared to a standard tendon sheath repair and a control. Eighty toes were divided equally into a control group, a sheath repair group, an HAp group, and an alumina group. Profundus tendons in zone II were divided and repaired after sublimis excision in all groups. In the sheath repair group, the flexor sheath was also repaired after suturing the tendon. In artificial sheath groups, sheaths made of HAp and alumina were placed over the repair sites to protect them from the surrounding tissues. In the control group, after repairing the tendon, the flexor sheath was excised and no artificial sheaths were used. Each toe was immobilized in a plaster cast for 3 weeks. After three weeks, the plaster cast was removed followed by the removal of the sheaths in the artificial sheath groups through a small incision in the skin in zone II. Active mobilization was encouraged in each group. Postoperative adhesions were examined at 3, 6, 9, and 12 week intervals by using light microscopic techniques. To further explore the effects of artificial sheaths on tendon healing, transmission electron microscopy was done for the HAp and alumina groups at 3, 6, and 12 week intervals. Results demonstrated decreased severity of postoperative adhesions in the HAp as well as in the alumina groups in comparison with the sheath repair and controls. A space resembling the fibro-osseous canal was formed around the tendon after removing the sheaths. This space remained patent until 12 weeks, 9 weeks after removing the sheaths, and a newly formed tendon sheath-like structure lined by synovial cells and with a peritenon-like structure over the tendon surface was observed. In the sheath repair and control groups, the severity of adhesions was decreased with the passage of time, to some extent due to unrestricted mobility. However, a newly formed tendon sheath or peritenon-like structure was not observed. Electron microscopic studies confirmed good healing at the suture in the HAp and alumina groups with no evidence of necrosis. These results are qualitative in nature as no statistical tests were performed. From these results we conclude that if the tendon is separated from the surrounding granulation tissue by a barrier with good biocompatibility, the tendon can heal with fewer adhesions. Artificial sheaths may be used to reduce adhesions in severe injuries of the hand where postoperative immobilization is necessary due to fractures, vascular, or nerve injuries. © 1995 John Wiley & Sons, Inc.
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  • 160
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    Journal of Applied Biomaterials 6 (1995), S. 65-68 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A natural poly(hydroxybutyrate-co-9% hydroxyvalerate) copolyester was processed into a three-dimensional porous foam structure by salt leaching/solvent casting with previously sieved sodium chloride salts. Laboratory-built P(HB-9% HV) foams and commercial collagen sponges were cut into small rectangular specimens, sterilized, and prewetted using ethanol, rinsed with Dulbecco's minimum essential medium + 10% serum culture media, and seeded with fibroblasts isolated from canine anterior cruciate ligaments. The fibroblast cultures into such porous substrates were performed from 0 to 35 days by incubation (5% CO2) at 37°C. It demonstrated that the P(HB-HV) sustained a cell proliferation rate similar to that observed in collagen sponges, up to at least 35 days, with a maximal cell density on the day 28 in culture. On the other hand, the P(HB-HV) materials kept their structural integrity during the culture period while the collagen foams contracted greatly. Further, the total protein production after 4 weeks in culture was found to be twice as high (190 ± 10%) in the P(HB-9% HV) foam than in the collagen foam. Porous P(HB-HV) materials appear to be adequate polymeric substrates for cell cultures. However, further evaluations are still required to confirm such preliminary results. © 1995 John Wiley & Sons, Inc.
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  • 161
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    Journal of Applied Biomaterials 6 (1995), S. 69-74 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Neodymium-iron-boron magnets are being increasingly used in orthodontic and orthopedic appliances. The purpose of this study was to investigate the in vitro cytotoxicity of these new “super” magnets. A modified agar overlay technique was performed using both L929 mouse fibroblasts and adult human oral mucosal fibroblasts. The neodyium-iron-boron magnets were tested in the following forms: uncoated magnetized, uncoated demagnetized, parylene coated demagnetized, and parylene coated magnetized. Results revealed that uncoated magnetized, uncoated demagnetized, and parylene coated magnetized were cytotoxic to both L929 mouse fibroblasts and human oral mucosal fibroblasts. However the parylene coated demagnetized neodymium magnets were only cytotoxic to the human mucosal fibroblasts. This study supports the hypothesis that these are cytotoxic effects of possibly corrosion products and of magnetism. The specific toxic effects of parylene were not examined in this present study. Statistical analysis (Mann-Whitney U-test, p = 0.014) suggested that, in this experiment, the human oral mucosal fibroblasts were more sensitive to the effects of these rare earth magnets. With the evidence of a biological effect, the use of implanted magnets must at present be limited until the safety can be assured. © 1995 John Wiley & Sons, Inc.
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  • 162
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    Journal of Applied Biomaterials 6 (1995) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 163
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    Journal of Applied Biomaterials 6 (1995), S. 75-83 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new bone cement was developed with the purpose of reducing the adverse biological effects during cementation of implants. This bone cement is characterized by lower exotherm, low release of monomer, low residual content of monomer, and retained physical properties. The essential innovation was substitution of half of the methylmethacrylate (MMA) in the monomer with long chain, high molecular weight, less volatile, and less soluble methacrylates (n-decylmethacrylate, isobornyl-methacrylate), as well as alteration of the accelerator system to a mix of dihydroxypropyl-p-toluidine and N,N-dimethyl-p-toluidine. The powder contains butyl-methacrylate-MMA copolymers. These measures lower the glass-transition temperature, and permit more complete mixing in an integrated package, mixing, and delivery system consisting of a vacuum packed, double chamber pouch. The porosity was reduced to about 2% and the largest voids measured 0.1 mm. The polymerization exotherm was reduced to 58 °C. The compressive strength was 82 MPa, the four-point bending strength 55 MPa, the flexural modulus 2.24 GPa, the tensile strength 32 MPa, and the shear strength 36 MPa. The fracture toughness was 0.89 MPa √cm. These mechanical properties together with the fatigue life were on level with manually mixed, conventional PMMA bone cements. © 1995 John Wiley & Sons, Inc.
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  • 164
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A Synthetic composite bone graft material, composed of fibrillar collagen, hydroxyapatite, and tricalcium phosphate, was evaluated in canine femoral shaft defects and compared to ungrafted defects and defects grafted with autogenous bone. The results of mechanical testing of the grafted femora in torsion at 1 year postoperatively were previously reported. This report details the histological and microscopic features of the graft sites. The results of this study suggest that the healing of the graft site is not yet complete at 1 year and that healing may be more complete in defects that received the synthetic graft as compared to ungrafted sites and autogenous bone graft. The bone tissue appears to respond to the graft particles as if they were bone particles. © 1995 John Wiley & Sons, Inc.
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  • 165
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    Journal of Applied Biomaterials 6 (1995), S. 109-116 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effects of metal ions released from orthopedic implants on nearby bone cells remain largely unknown. The purpose of this study was to examine the acute toxicity of metal ions on osteogenic cells derived from bone marrow. Bone marrow stromalcells were cultured with metal ions found in commonly used orthopedic implants, that is, Ti-6Al-4V, Co-Cr-Mo, and 316L stainless steel. Solutions of individual ions and combinations representing the alloy composition were prepared from atomic absorption standards and added to the cultures to give concentrations ranging from 50 ppb to 5o ppm. After a 48-h period of exposure to ions, the bone marrow cultures were examined for effects of cytotoxicity by measuring total cell number, total cell protein, and mitochondrial activity. Cr6+ was grossly cytotoxic; Co2+, Mo6+, Fe3+, and Ni2+ were moderately cytotoxic; and Ti4+, Al3+, V5+, and Mn2+ were minimally toxic, as determined by the assays used. Ion solutions representing Co-Cr-Mo and 316L stainless steel were moderately toxic; solutions representing Ti-6Al-4V were toxic at only the highest concentrations used. The observed cytotoxicity was time-dependent, with irreversible toxic effects being initiated following as short as a 3- to 6-hour exposure. These results show that metal ions associated with Co-Cr-Mo and 316L stainless steel are toxic to osteogenic cells at concentrations approximating those measured in the fibrous membrane encapsulating orthopedic implants. © 1995 John Wiley & Sons, Inc.
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  • 166
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    Journal of Applied Biomaterials 6 (1995), S. 117-123 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The main function of the intervertebral disc is to transmit and attenuate compressive and torsional forces, and stabilize the intervertebral joint. Unfortunately, the disc may be displaced or damaged due to trauma or disease causing the nucleus to herniate and protrude into the vertebral canal or intervertebral foramen. Pressure on the spinal nerve may cause pain or paralysis in the area of its distribution. At present, the surgical procedures used to alleviate this condition include disc excision, and/or spinal fusion. A more desirable situation would involve removing the nucleus pulposus and part or all of the annulus fibrosis and implanting a suitable biofunctional equivalent. Such a prostheis should attenuate stresses and prevent abnormal stress at adjacent intervertebral joints. Maintenance of normal disc height would prevent impingement of the posterior facet joints and facet joint syndrome. In a previous companion paper (J. Applied Biomat. 5:125-132; 1994), the mechanical behavior of disc prostheses manufactured from fiber reinforced, elastomeric thermoset resins were examined. In order to develop devices which were more practical from a manufacturing standpoint and extremely reproducible, the fiber reinforced thermoset resins were replaced by multi-durometer thermoplastic elastomeric materials. In the present paper, the mechanical properties of thermoplastic multicomponent desings have been investigated. © 1995 John Wiley & Sons, Inc.
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  • 167
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The present study was conducted to compare the push-out strength of the treated and control samples obtained after implantation of intramedullary rod in canine femurs with bone cement to simulate the femoral stem implantation for 2 weeks, 3 and 6 months. Contralateral femur served as control. The result showed a significant decrease in push-out interfacial strength after shock wave treatment (average 48.4% decrease compared with control, p 〈 0.0001) which is similar to the in vitro results. There was no significant difference if the shock treatment was applied and left for 2 weeks or 4 weeks compared to the ones tested immediately after sacrifice. There were some soft tissue damage immediately following shock treatment in the focal area but this returned to normal in 2 weeks. Human cadaveric femoral bones and the canine bone (the dosage level was higher for the human bone than canine). The number of impacts used to extract the bone cement plug out of a human femur segment (5-cm long) decreased about 68% at 23 and 25 kV treatment power level. These preliminary studies indicate that the shock wave can be utilized to reduce the interfacial strength of the bone and bone cement although more studies are needed to assess its efficacy in terms of cost, long-term effect on patients and the exact mechanism of the loosening before this technique can be used clinically.
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  • 168
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    Journal of Applied Biomaterials 2 (1991), S. 269-271 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 169
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    Journal of Applied Biomaterials 2 (1991), S. 261-267 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A transparent poly(vinyl alcohol) hydrogel disc covalently immobilized with Type I collagen, fibronectin, and an adhesive oligopeptide and preseeded with corneal epithelial cells was implanted in rabbit cornea using a technique of lamellar keratoplasty, and the tissue response was studied by light and electron microscopy. Covalent immobilization of type I colagen on the surfaceof hydrogel was found to support growth and adhesion of the corneal epithelium in vitro. the in vivo experiment showed that cell seeding could prevant infection of the hydrogel. However, the implanted disc was rejected from the host cornea by epithelial downgrowth and the exchange between the seeded cells and host corneal epithelia was not observed until 14 days after surgery. The rejection might have occurred because of unsatisfactory fixation of the hydrogel to the host cornea.
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  • 170
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    Journal of Applied Biomaterials 2 (1991), S. 277-280 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 171
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    Journal of Applied Biomaterials 1 (1990), S. 127-136 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Traditional water permeability evaluation procedures developed for measurement of gross leakage rates of textile prostheses are not adequate for testing the permeability of low-porosity bio-impregnated vascular prostheses. Obtaining reliable water permeability data for these low porosity grafts requires a technique that can accurately assess minor water leakage under the applied pressure. This study proposes an automated method for graft permeability assessment which measures the pressure change inside the graft sample as a function of water loss. The new unit of water permeability defines the pressure gradient at the given initial conditions. The proposed method for evaluating the water permeability of bio-impregnated vascular prostheses provides highly reliable data, is accurate, and excludes human error.
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  • 172
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    Notes: Knot slippage continues to be a serious concern in surgery. This study explored the possibility of improving knot performance by exposing it to radiation from a CO2 laser. The specimens were mounted in a special device and exposed in a predetermined position for precisely controlled lengths of time. In the first set of experiments, the welding of ends was examined in nylon and polyester sutures. Although the welding was easily achieved, the joint was found brittle and its strength lower than that of a surgical knot. In the next set of experiments, the work was performed at a more fundamental level using oriented, high density, polyester films. The results showed that up to a certain level of exposure the tensile properties did not change, but beyond it a rapid decay took place. Shear tests on polyester sutures twisted together and then exposed to various levels of energy indicated that a bond of maximum strength developed at this exposure. Mersilene sutures of size 3/0 containing a two throw square knot when exposed to energy of this level produced optimal results. The knot strength increased by about 16% (from 13.4 N unexposed to 15.6 N exposed) and the slippage often known to occur in a two-throw knot was completely absent. This work performed under standard atmospheric conditions provided a direction for greatly enhancing the performance of a two-throw knot in terms of both the security and the strength. The investigation, however, must now be extended to other suture materials and sizes and to in vivo environments to realize the gain in actual surgery.
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  • 173
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    Journal of Applied Biomaterials 1 (1990), S. 295-305 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Two types of hydroxylapatite (HA) surface coatings were tested as a means for bone attachment to polysulfone implants. The first coating was a roughened surface that was created by imbedding particulate HA in a polysulfone (PS) rod. The second surface was a smooth surface where HA particles were imbedded in the PS rod and the surface of the composite machined smooth. The smooth surface permitted only bonding of bone to exposed HA: whereas, the rough surface permittted mechanical interdigitation and bone bonding to HA. Specimens were implanted transcortically in the distal femurs of 12 rabbits, and groups of 4 were sacrificed at 4, 12, and 26 weeks. The attachment strength between bone and the HA/PS implants was determined via a push-out test. The results showed a statistically significant increase in push-out force for the rough surfaced implant when compared to the smooth surfaced implant at each time period. Histological analysis of samples from the in vivo study showed what appeared to be direct bone attachment on both the rough and smooth HA/PS implants.
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  • 174
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Anodic polarization measurements of several orthopaedic implant alloys - AISI 316L stainless steel, Co—Cr—Mo alloy (ASTM F-75), nickel-titanium (NiTi) alloy, commercial pure titanium, and Ti—6Al—4V - were carried out in Ringer's solution containing 1% bovine serum albumin (BSA) and in simple Ringer's solution. Constituent metals in the medium were analyzed by inductively coupled plasma emission spectrophotometry after measurements. Pitting potentials and total anodic current of former two alloys were constant in the two mediums and not affected by the addition of bovine serum albumin. However, the amount of dissolved metals from pure nickel and AISI 316L stainless steel were increased by the addition of BSA; dissolved metals from Co—Cr—Mo alloy were decreased by it.
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  • 175
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Nylon monofilament sutures were tested in a straight pull as well as a conventional knot pull tensile test. In each test, sutures were evaluated following storage under prevailing atmospheric conditions or saturation in whole human blood. Blood saturation decreased the ultimate tensile strength by as much as 20%. The present investigation of sutures that were stored under prevailing atmospheric conditions substantiated the proposal previously made for polypropylene monofilaments-that 60% of the ultimate tensile strength could be established as a fundamental USP criterion for Class I monofilament sutures.
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    Journal of Applied Biomaterials 3 (1992), S. 59-62 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The methods usually employed for the histological processing of orthopaedic specimens of cemented joint arthroplasties involve treatment with methacrylate monomer and organic solvents which dissolve the polymethylmethacrylate cement. This may distort the intimate relationship of the cell layers along the surface of the interface between the bone and the cemented implant. The authors report on a technique for the processing and embedding of cemented orthopaedic implants which permits preservation of the polymethylmethacrylate cement. The method utilizes a modification of Spurr's low viscosity epoxy resin and avoids the use of solvents such as acetone. Undecalcified sections of cemented joint replacements from animal studies and human specimens have been prepared using this method. It is possible to use these sections for detailed histomorphologic and histomorphometric analysis of bone tissue and of the soft tissue membrane adjacent to the polymethylmethacrylate cement.
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    Journal of Applied Biomaterials 2 (1991) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 178
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    Journal of Applied Biomaterials 4 (1993), S. 195-209 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Organizing and accessing biomaterials-related information is problematic because of the interdisciplinary nature of the field. Relevant information appears in the literature of numerous science and technology subdisciplines and there is no one index or database that covers all of the related publications. An additional barrier to information retrieval is the lack of a thesaurus for the field. Multiple terms representing the same concepts are currently employed and it is not always readily apparent which terms to use in a literature search. As an aid for students and researchers in the discipline, the author provides an indexed bibliography of English language monographic works on biomaterials and biocompatibility published after 1973. © 1993 John Wiley & Sons, Inc.
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    Journal of Applied Biomaterials 4 (1993), S. 183-194 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The failure of most percutaneous devices (PD) is caused by infection initiated by a lack of a tight seal at the skin-device interface. This interface can be disrupted by both extrinsic and intrinsic forces. Many stress reduction methods have been proposed, the most common being the application of a subcutaneous flange. It is widely believed that the bending compliance of the flange plays a significant role in the success or failure of a PD.A study was conducted to observe the effect of flange compliance on local host response in both a functional and nonfunctional setting. Two PDs having flanges with different bending rigidities were implanted percutaneously in goats (n = 8). After a healing period of 2 weeks, half of these devices were externally stimulated with a random load. All the implants were retrieved after 4 weeks and evaluated histologically.The tissue capsule was significantly thicker and the incidence of severe fibrosis and/or necrosis was higher at the flange rim of the functional implants, irrespective of flange compliance. The more compliant devices were encapsulated with a thick fibrous capsule more frequently than the less compliant ones, irrespective of functional status. The more compliant devices also had a greater incidence of foreign body giant cells in the corner region and elicited severe acute inflammation at the corner and top of the flange more frequently than the less compliant implants. Numerous areas of degenerating foreign body giant cells accompanied with fibroblastic proliferation and dystrophic mineralization were identified in many of the capsules beneath the flanges.It was concluded that the rigid implants elicited a more desirable tissue response than the compliant implants while the functional implants elicited a less desirable response than the nonfunctional ones. There was no synergistic or antagonistic relationship between the functional status of the device and flange compliance. © 1993 John Wiley & Sons, Inc.
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  • 180
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    Journal of Applied Biomaterials 4 (1993), S. 213-219 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The aim of this study was to investigate the bone response to three different types of titanium (Ti) alloys and hydroxyapatite (HA) coated titanium alloy by histological and histomorphometrical analysis. Therefore, implants made of these materials were inserted into the tibia of rabbits. Implantation times were 6 and 16 weeks. The histological evaluation included measurement of the amount of bone apposition and analysis of the bone reaction and interface characteristics around the implants. The results demonstrated no marked differences in bony reaction to the different implant materials. In addition, the HA coatings showed loss of thickness. © 1993 John Wiley & Sons, Inc.
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  • 181
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Hydroxyapatite induction by a synthesized pure silica hydrogel was examined in various simulated body fluids (SBFs) having different magnesium, calcium, and phosphate ion concentrations as well as pH values. The silica hydrogel generated biologically active apatite on its surface by taking up calcium and phosphorous ionic groups from a surrounding SBF that was prepared to emulate the human plasma in inorganic composition. The induction period for apatite nucleation on the surface of the silica was largely decreased with the addition of a small amount of the calcium or phosphate ions to the SBF and with an increase in pH, but increased with the addition of magnesium ion. Bioactivity of bioactive materials like Bioglass® and glass-ceramic A-W was well interpreted in terms of the rate of apatite formation reflected in these results. Moreover, the results provide the basic knowledge for designing new bioactive materials. © 1993 John Wiley & Sons, Inc.
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  • 182
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    Journal of Applied Biomaterials 1 (1990), S. 249-251 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 183
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    Journal of Applied Biomaterials 1 (1990), S. 233-240 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The capability of ALCAP ceramic drug-delivery implantable devices to release testosterone for 12 months was investigated. A total of 120 Sprague-Dawley male albino rats were distributed equally into three groups. Two ALCAP capsules, one nonimpregnated and the other impregnated with polylactic acid (PLA) were implanted into each rat in Groups I and II. Capsules implanted into Group I rats were loaded with 40 mg testosterone (T) each. Group II rats were implanted with two empty capsules (sham group), and Group III animals served as unimplanted controls. Eight rats from each group were euthanized at the end of 1, 3, 6, 9, and 12 months following the implantation of the ceramics. No significant changes in the weights of vital organs of rats were observed between any of the three different groups. Vas deferens and epididymal fluid were devoid of normal spermatozoa within 3 months of implanting the steroid-containing ceramics. Testes and epididymis weights decreased significantly in the rats implanted with ALCAP ceramics containing steroid, and the seminiferous tubules became oligospermic after 1 month and azoospermic after 3 months. Circulating levels of both LH and FSH hormones were suppressed in experimental rats. Serum T level was lower than the control but showed no significant difference in comparison to control rats. The data collected in this study suggest that: (a) ALCAP ceramic capsules are capable of delivering T in a sustained manner for 12 months; (b) T delivered by ALCAP capsules can be used effectively to regulate spermatogenesis in rats.
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  • 184
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    Journal of Applied Biomaterials 1 (1990), S. 241-248 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Long-term in vivo strain sensing would provide information about deformation changes adjacent to implants during bone remodeling. Biodegradation of the cyanoacrylate adhesive commonly used to attach strain gauges to bone has generally limited in vivo strain sensing to time periods less than one month.Hydroxyapatite (HA) which has been used to attach implants to bone in vivo, was attached to strain gauges using a solvent-thinned polysulfone solution. Three HA-polysulfone surface morphologies were tested in a preliminary bench-top test. The single layer pressed surface morphology, which responded most accurately during bench-top testing, was modified slightly and applied to two gauges which were implanted on the femur of a greyhound.Strain measurements from the HA-backed gauges in place for four months in vivo were compared to strains measured from the contralateral femur. Comparison of the results indicated these gauges were well-bonded and that they were sensing strain accurately. After embedding in PMMA, the femur having the HA-backed gauge and the control femur were sectioned at the level of one of the HA-backed gauges, Microradiographs of these sections indicated no adverse tissue response to the HA-backed gauge on the endosteal or periosteal surface.
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  • 185
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    Journal of Applied Biomaterials 4 (1993), S. 277-277 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 186
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Median nerve regeneration was studied in 30 adult primates after repair by microsurgical suture or tubulization with a nonwoven, bioabsorbable, polyglycolic acid device. The two methods were compared electrophysiologically and histologically 6 and 12 months after repair. The electrophysiology included recording of electrically evoked compound action potentials and subsequent determination of threshold, conduction velocity, amplitude, and area above the baseline for each component. Measurements were obtained before nerve transection and at the time of biopsy by stimulating both proximal and distal to the transection site. Analysis of all electrophysiological parameters revealed no statistically significant differences (p 〈 0.05) between the two repair techniques. Histopathology included examination of cross sections proximal and distal to the repair sites and longitudinal sections through the coaptation site. End organs (Meissner's and Pacinian corpuscles and muscle) were sectioned to determine the degree of reinnervation. No significant differences between the repair techniques were observed by histological analysis of these sections. These evaluations indicated that the tubulization repair technique produced results comparable to that of the suture technique. © 1993 John Wiley & Sons, Inc.
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  • 187
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    Journal of Applied Biomaterials 1 (1990) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 188
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    Journal of Applied Biomaterials 1 (1990), S. 279-287 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Repeated needle trauma to grafts used for chronic hemodialysis may result in loss of graft integrity and aneurysmal formation. The gross and scanning electron microscope observations of the virgin expanded polytetrafluorethylene graft (ePTFE) material following repeated needle punctures are presented. Understanding how the normal structure of the ePTFE graft can be affected, particularly by larger diameter needles, underlines the effect and importance of needle puncture technique. In assuming that aneurysm related to needle punctures is the only evolutive complication of the vascular access, this analysis showed that the half life of an ePTFE prosthesis which was 6 mm in diameter and 25 cm in length was reached after about 1512 punctures using the 1.8-mm diameter hemodialysis needle, 1111 punctures with the 2.1-mm diameter needle or 784 punctures with the 2.5-mm diameter needle.
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  • 189
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    Journal of Applied Biomaterials 1 (1990) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 190
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    Journal of Applied Biomaterials 1 (1990), S. 1-1 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 191
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Medicine , Technology
    Notes: Adhesion formation associated with tendon surgery is a widespread problem in which a healing tendon becomes adherent via scar tissue to surrounding structures such as bone, muscle, skin, tendon sheath, or other tendons. A model is described in which adhesions were generated reproducibly between the plantaris and Achilles tendons of the rabbit using a partial tenotomy, a Bunnel suture, and immobilization. Using this model, the effect of an absorbable barrier, INTERCEED (TC7),INTERCEED (TC7) Absorbable Adhesion Barrier is a trademark of Johnson & Johnson Patient Care Inc. on adhesion formation was investigated. This material, which is a fabric comprised of oxidized regenerated cellulose, was found to diminish significantly the extent and severity of intertendinous adhesions, assessed both mechanically and histologically. No evidence of a foreign body reaction was observed.
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  • 192
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    Journal of Applied Biomaterials 2 (1991), S. 143-145 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 193
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    Journal of Applied Biomaterials 4 (1993), S. 77-85 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Stents are tubular devices that are used in cylindrical passages of the body following trauma or disease in order to keep the cross section of these passages open. A mathematical model of a self-expanding metallic stent has been developed with the aim of predicting various geometrical and mechanical properties of the stent. The model was developed with the main assumptions that the stent acts as a combination of a number of independent open-coiled helical springs with ends fixed against rotation, and that the springs undergo elastic deformations only. A series of experiments has been carried out in order to assess the validity of the model. The experimental results show good agreement with theory for the tests involving stent diameter and longitudinal force as a function of stent length and fair agreement, limited by frictional effects, for the tests involving radial pressure as a function of stent diameter. © 1993 John Wiley & Sons, Inc.
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  • 194
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    Journal of Applied Biomaterials 4 (1993), S. 67-72 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Fibroblast growth factor (FGF) is a polypeptide that has been shown to have a stimulatory effect on osseous tissues in vitro. This study characterized the release of FGF from plaster of Paris (PLP) and measured the dissolution of PLP in various solutions with the aim of developing a reliable carrier system for the release of FGF in vivo. The study consisted of five experiments: (I) FGF diffusion from PLP pellets, (II) FGF diffusion from PLP discs, (III) PLP dissolution in saline, (IV) PLP dissolution in serum, and (V) FGF adsorption by commercially pure titanium. FGF was observed to be released at a rate directly proportional to the rate of dissolution of the PLP carrier, suggesting that either the FGF binds to the PLP; or, alternatively, the FGF may be entrapped by the PLP. Dissolution rate, and thus release rate, could be varied by varying the mass of the carrier. Greater diffusion of FGF was observed in larger, more slowly dissolving PLP carriers. Dissolution of PLP was observed to be slower in serum than in saline, apparently due to stabilization by factors in the serum but not due to a concentration gradient effect. Titanium coupons did not adsorb significant amounts of FGF. These results indicate that PLP, which has been shown in the past neither to FGF. These results indicate that PLP, which has been shown in the past neither to aggravate inflammatory response nor to interfere with bone ingrowth, may serve as delivery vehicle for FGF to osseous tissues in vivo. © 1993 John Wiley & Sons, Inc.
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  • 195
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    Journal of Applied Biomaterials 1 (1990), S. 21-30 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Fatigue crack propagation in a notched specimen under cyclic loading was investigated for a series of experimental composite resins and six commercial composites. The fatigue resistance was measured as a function of filler content, water absorption, and post-curing temperature. Constants A and m of the Paris law have been obtained by linear regression analysis. The plot of fatigue resistance against volumetric filler content, V shows a sigmoidal relationship wiht a rapid increase in the range of V = 40-50% then tapering off at higher V. A substantial increase in the constant m of the Paris law was found for water-saturated commercial composite resins. Although increasing the post-curing temperature from 37°C to 70°C results in a 10% increase in fracture resistance, a high post-curing temperature is not favorable for highly filled composites (V 〉 60%) where more strained areas can be induced unless polymerization shrinkage is minimal. The ranking of fracture resistance for the commercial materials is: Occlusin 〉 P30 ≃ Adaptic II ≃ Ful-Fil 〉 Isomolar 〉 LC33. Based on the assumption that microcrack growth in the subsurface damage layer is the precursor of wear, fatigue resistance combined with fracture toughness satisfactorily predicted the clinical wear of commercial composites. Surface microfracture which amplifies the subsurface flaw size and creates undesirable stress concentrators can be subdued by high fracture toughness. In addition, high fatigue resistance retards the formation of wear particles, thereby reducing loss of material from the composite surface.
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  • 196
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Distortion of ceramometal restorations during porcelain application is often attributed to mismatch of thermal expansion coefficients. Little attention has been paid to treatment the metal receives after casting. Oxide formation, lattice parameter changes, and macroscopic distortion were studied for flat specimens of two ceramometal alloys, a high Pd alloy and a high Au alloy. SnO2 and In2O3 formed on the surface of the high Au alloy after the oxidation firing, while SnO2 and CuGa2O4 formed on the high Pd alloy. Lattice parameter changes reflected the loss of base metal elements in the formation of surface oxides. The edges of specimens distorted toward the ground side. Such distortion can be explained by the induction of residual stress in the metal surface during grinding and subsequent surface stress annealing accompanied with subsurface elastic recovery during firings. Oxide formation was not related to specimen distortion. This study suggests a relationship between surface preparation and specimen distortion during porcelain application procedures.
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  • 197
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    Journal of Applied Biomaterials 4 (1993), S. 107-107 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 198
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To assess new and existing materials for total joint arthroplasty, the authors performed a comprehensive histomorphologic and morphometric analysis of bone to cylinders implanted transversely in the proximal tibia of mature New Zealand white rabbits. Four sterile, cylindrical implants measuring 6.1 × 3.8mm were manually inserted through drill holes in both tibiae with a „line-to-line fit.“ The materials tested included: ASTM F-75 cast cobalt-chrome-molybdenum alloy, commercially pure titanium wrought zirconium-2.5 niobium alloy, zirconium oxide coated zirconium-2.5 niobium alloy, wrought titanium-13 niobium-13 zirconium alloy, and nitrogen diffusion hardened titanium-6 aluminum-4 vanadium alloy. Control animals with or without drill holes were included. The animals were killed by barbiturate overdose 6 months postoperatively. The upper tibiae were harvested and processed for undecalcified histologic sections that were stained with toluidine blue. The sections were examined by an investigator blind to the identity of the implanted materials. A full necropsy was also performed.A collar of lamellar bone, of variable length and thickness, continuous with the original cortex formed a buttress around the implants. There was no evidence of foreign body or inflammatory reaction. The marrow was slightly fatty, but cells of allthree hematopoietic lines were identifiable. The materials investigated had the following ranking in decreasing order of bone contact: Ti-13Nb-13Zr 〉 nitrogen hardened Ti-6Al-4V 〉 C.P. titanium 〉 Zr 2.5Nb 〉ZrO2 coated Zr-2.5Nb 〉 cast Co—Cr alloy. The difference between the groups was statistically significant (p = 0.05). For the variable „average bone layer thickness“ the ranking in decreasing order was: nitrogen hardened Ti-6Al-4V alloy = C.P. titanium 〉 Ti-13Nb-13Zr 〉 ZrO2/Zr-2.5Nb 〉 Zr-2.5Nb 〉 cast Co—Cr alloy (p = 0.19). For the variable „average bone layer thickness in bone contact regions,“ the ranking of the values, in decreasing order were: nitrogen hardened Ti-6Al-4V 〉 C.P. titanium 〉 ZrO2 coated Zr-2.5Nb 〉 Ti-13Nb-13Zr 〉Zr-2.5 Nb 〉 cast Co—Cr alloy (p = 0.02). The final necropsy reports of the animals identified no adverse findings that were concentrated to any particular implant group. The new, lower modulus materials Ti-13Nb-13Zr and Zr-2.5 Nb, and nitrogen hardened Ti-6Al-4V appear to have a similar or superior bone response to Co—Cr alloy when implanted in the rabbit tibia model. © 1993 John Wiley & Sons, Inc.
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  • 199
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    Journal of Applied Biomaterials 4 (1993), S. 127-134 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of pulsed electromagnetic fields (PEMFs) on the foreign body response to particulate debris, similar in morphology and quantity to wear debris present in the tissues around loose total joint prostheses, was investigated using a rabbit model. Cobalt chrome pins were inserted into the femurs along with particulate debris consisting of ultra high molecular weight polyethylene (UHMWPE), polymethylmethacrylate (PMMA), and cobalt chrome (CC). The particles induced a significant cellular response compared to the control animals that did not receive any debris. The application of PEMFs did not increase this foreign body response, nor did it have an effect on the number of resorption cavities, cortical area, or cortical thickness. © 1993 John Wiley & Sons, Inc.
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  • 200
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    Journal of Applied Biomaterials 4 (1993), S. 135-141 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We have developed a bioactive bone cement consisting of silane-treated CaO—SiO2—P2O5—CaF2 glass powder as the filling particles and bisphenol-a-glycidyl methacrylate (BIS-GMA) diluted with triethylene-glycol dimethacrylate (TEGDMA) as the organic matrix. Histological examination demonstrated direct bonding between the cement and bone along the circumference of the cement at 4 weeks after implantation in rat tibia. The compressive strength and toughness of the cement were two and four times greater than those of polymethylmethacrylate (PMMA) cement, respectively. The inflammatory reaction of the skin caused by the new cement was not as intense as that for PMMA 3 days after subcutaneous implantation. This new cement may be applicable as a bioactive bone cement with high mechanical strength. © 1993 John Wiley & Sons, Inc.
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