Biomaterials.info - Resources for Engineers

Record 221 to 240

[Microrough surface and its bio-effects of metallic biomaterials (II)--bio-effects of microrough surface of metallic biomaterials]
Wen, X. (1997), Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 14(2): 164-9.
Abstract: As for bio-effect of microrough surface of metallic biomaterials, seven aspects are reviewed in this article: i.e., the relationship between microrough surface (MRS) and corrosion resistance, ion release rate; the relationship between MRS and inflammation; the relationship between MRS and epithelium cells, fibroblast cells; the relationship between MRS and soft tissue; the relationship between MRS and bone; the relationship between MRS and blood tissue; the relationship between MRS and microorganism, contamination, decontamination. To sum up, MRS has its advantages in biocompatibility.

[Model for immunologic testing of biomaterials]
Thull, R., K. Trautner, et al. (1992), Biomed Tech (Berl) 37(7-8): 162-9.
Abstract: Corrosion products and electric fields are capable of changing proteins to antigens, thus permitting the immunological system to identify the biomaterial as foreign. The reaction between corrosion products and a macro-molecule also leads to an antigen (carrier antigen), such as conformational changes of a macro-molecule, e.g. a protein, caused by the electric field at the implant surface (modified macro-molecule antigen). While the sensitivity to corrosion and the effectiveness of galvanic elements is measurable by electrochemical methods, suitable methods of determining the field strength in the vicinity of biomaterial surfaces are still unavailable. The influence of the double layer of uncoated and coated titanium surfaces on the conformation of proteins and their conversion to antigens are investigated with polyclonal antibodies capable of identifying the unchanged protein despite adsorption to the surface. 14C-marked Bovine Serum Albumin serves as a model protein. Determination of the total number of protein molecules adsorbed is effected via the detection of the emitted electrons. The quotient of the concentration of natural proteins to the concentration of adsorbed molecules gives the biocompatibility index, which is independent of the surface area, and gives an indication of the expected biocompatibility of the material. The results of the biological tests of titanium and two coating materials on titanium were confirmed in an animal experiment. It is possible that in the future immunological tests may replace experiments in animals.

[Morphology of isolated bone resorbing cells on different biomaterials]
Lambrecht, J. T. and R. Ewers (1988), Dtsch Zahnarztl Z 43(1): 113-5.

[Natural coral used as a replacement biomaterial in bone grafts]
Patat, J. L. and G. Guillemin (1989), Ann Chir Plast Esthet 34(3): 221-5.
Abstract: Natural coral, submitted to rigorous protocols of preparation and purification, can be used as a replacement biomaterial for bone grafts both in orthopaedic surgery and maxillo-cranio-facial surgery and neurosurgery. Experimental studies commenced in 1977 and human clinical applications, commenced in 1979, have largely demonstrated the biocompatibility of the material and its entirely original nature. This biomaterial is progressively and totally replaced by newly formed bone with, after completion of the restoration process, has the characteristics of the recipient bone.

[Necessity and validity of standard models for experimental preclinical evaluation of biomaterials. An example of biologic characterization of a hydroxyapatite-based implant material]
Caropreso, S., L. Cerroni, et al. (1997), Minerva Stomatol 46(1-2): 45-50.
Abstract: A large number of methods are now available for the preclinical screening of implantable materials concerning their biocompatibility and their ability to stimulate tissue formation. In vitro techniques represent a very useful tool, since this way we can realistically simulate the biological events which occur in vivo at the bone-implant interface. In the present study scanning electron microscopy and light microscopy observations were performed in order to assess the effect of an hydroxyapatite granulate on cell behaviour and morphology. Uptake of proteins to hydroxyapatite surface has been also investigated by comparing the amounts adsorbed after incubation with bovine serum albumin and bovine pancreaticamilase. According to our preliminary observation cells do not show signs of toxicity or inhibition of cell growth even after 14 days of co-culture with hydroxyapatite. Granules were covered by an uninterrupted cell layer by day seven. Even after two days micrographs show cells anchored and spread over the surface of the underlying granules, with a flattened and stellate shape. Such a morphology indicates a very high cellular activity, suggesting that the interaction with hydroxyapatite seriously increased metabolism. Measurements of protein adsorption on the hydroxyapatite surface show that changes in the size of particles affect the binding of proteins, while, in the case of granular hydroxyapatite, despite changes in size of granules, variations of protein adsorption were not observed, neither in relation to their different isoelectric point. Our preliminary results represent a good example of the opportunities presented by an experimental in vitro model.

[New biomaterials and cataract surgery]
Aron-Rosa, D. (1995), Bull Acad Natl Med 179(3): 557-66; discussion 566-7.
Abstract: In 1949, Harold Ridley implanted the first intraocular lens, after cataract surgery, he had chosen as the best available material Polymethyl Metacrylate noticing during the war in the injured eyes of the R.A.F. Pilots that the material was perfectly tolerated inside the eye as a foreign body. It took 10 years for intraocular lenses to take off, due to the necessary improvement of both surgery and manufacturing, since then all the intraocular lenses are made of the same material and perfectly tolerated. However the material is hard and not foldable. The improvement of Phakoemulsification have made small incision (3.2 mm) surgery possible, however there is a need for new foldable implants that can be inserted into the eye through a small incision, so rather new bio material are now being used. A variety of silicone foldable lenses have been proposed, their advantages are: easy foldability, solidity and injectability through an injector. Their disadvantages are, as compared to the 40 years standing solid PMMA lenses; less biocompatibility changes in color and apparition of crystal precipitates. Also reports on induced polyarthritis, lupus and paraneoplasic syndromes with other silicone prosthesis, these complications appear after 5 or 6 years. Although new silicone lenses are being brought on the market, there is some hesitation in implanting these lenses on patients less than 80 years of age. Polyhema lenses appeared in 1985, with 38% water content. The material is perfectly biocompatible even more than PMMA, however their initial design was not adequate until 1992. Their advantages are perfect biocompatibility over the years, autoclavability. Their only disadvantage a certain fragility during folding. Our 7 years experience with silicone and hydrogel has shown that 20% of the first silicone lenses had to be exchanged between 3 to 4 years after surgery and 0% of the polyhema. Posterior capsule opacification at 1 year was twice more frequent with silicone than with PMMA or hydrogels and that mild chronic uveitis occurs 3 times frequently with silicone lenses.

[New biomaterials in orthopedics]
Langlais, F. (1985), Presse Med 14(26): 1424-8.
Abstract: To develop new materials for articular prostheses seems particularly desirable since at present these do not appear to last for more than 1 or 2 decades. Improvements in our knowledge of prosthesis degradation has resulted in new, so-called "biomaterials" being proposed to cope with the various factors involved in disinsertion of artificial joints, viz, body tolerance to debris from wear or corrosion (biocompatibility), mechanical properties of the material, such as resistance to fatigue and wear and elasticity (biocompetence) and mechanical principles underlying arthroplasties (biomechanics). Current trends therefore are towards titanium alloys which are both resistant and similar to bone in elasticity, towards friction torques producing fewer or better tolerated debris (aluminium-coated polyethylene) and towards better means of fixation. Owing to the great complexity of tolerance mechanisms and to the functional character of orthopaedic surgery, very stringent testing is required before new products are in clinical use. While these products are slowly made available to surgeons, many significant improvements in existing materials (polyethylene and cements) are being achieved.

[New methods for the prevention of posterior capsule opacification]
Auffarth, G. U., T. M. Rabsilber, et al. (2005), Ophthalmologe 102(6): 579-86.
Abstract: Even though tremendous advances have been made especially during the last 10-15 years in terms of surgical techniques and improvement of implant technology, posterior capsule opacification (PCO) still remains a serious long-term complication. New clinical and laboratory studies (especially of autopsy eyes) have improved our understanding of how IOL design and material influence PCO. Sharp edge optic designs of IOLs of various materials have been shown to significantly reduce secondary cataract. The application of pharmacological substances selectively into the capsular bag is now possible due to the development of the PerfectCapsule System for vacuum-sealed capsule irrigation. Major advances in other areas of biotechnology and immunology including gene therapeutic methods offer totally new approaches for the future in the elimination of lens epithelium cells from the capsular bag. This survey gives an update on current and future means and trends to reduce or prevent PCO formation.

[New-bone formation by osteogenic protein-1 and autogenic bone marrow in a critical tibial defect model in sheep]
Regauer, M., I. Jurgens, et al. (2005), Zentralbl Chir 130(4): 338-45.
Abstract: AIM: Osteogenic Protein-1 (OP-1) is known to be a very potent osteoinductive growth factor. However, experimental studies using critical-size defect models in the weight-bearing lower extremity show non-uniform results. Therefore, we studied the osteoinductivity of OP-1 in a tibial worst-case defect model in sheep. Potential improvement of OP-1 induced new bone formation using a composite graft with autogenous bone marrow was to be investigated. METHOD: In 19 sheep a 5 cm segmental defect of the tibial diaphysis was treated by intramedullary nailing and filled with the following implants: 5 mg OP-1 + inactivated demineralized bone matrix (group 1; n = 6); 5 mg OP-1 + inactivated demineralized bone matrix + 5 ml autogenous bone marrow (group 2; n = 5); autogenous cancellous bone (group 3; n = 4), or inactivated demineralized bone matrix + 5 ml autogenous bone marrow (group 4; n = 4). RESULTS: In total, 3 out of 10 defect sites treated with OP-1 were completely bridged radiographically by 12 weeks. Initially, x-rays showed accelerated new bone formation by use of the composite grafts containing OP-1 and autogenous bone marrow. However, 12 weeks post surgery 3D-CT-volumetry could not detect significant differences of new bone formation within the defect sites treated by OP-1 with or without bone marrow, while new bone formation by autogenous cancellous bone was better than by OP-1. CONCLUSION: In our worst case defect model, the osteoinductive potential of OP-1 is initially accelerated but 12 weeks post surgery not increased when combined with autogenous bone marrow transplantation. So far, critical segmental bone defects of the weight-bearing lower extremity can not be bridged regularly in our model by use of OP-1. Therefore, for the treatment of such critical defects with rotational instability the examined application device of OP-1 can not yet be recommended.

[Nude stents, coated stents]
Puel, J. (2005), Bull Acad Natl Med 189(2): 237-47.
Abstract: By making safe the act and decreasing the restenosis risk, the stent had contributed to the development of coronary artery angioplasty which fill nowadays the whole of clinical and coronarographical field of coronary artery disease. The new stent, coated with substances amenable to minimise the best the restenosis risk, holds the hope of the interventional cardiology. The first results are promising. If the coated stent is effectively efficient in preventing restenosis, it has to prove his efficacy on the strong criterion of mortality and myocardial infarct recurences.

[One hundred years of orthopedics in the Netherlands. VII. biomaterials]
Heyligers, I. C., W. J. Dhert, et al. (1998), Ned Tijdschr Geneeskd 142(19): 1079-84.
Abstract: The use of biomaterials in orthopaedics is becoming increasingly important. They are widely used in artificial joints, as bone replacement material and as resorbable material. Also (recombinant) bone morphogenetic proteins are used. Classification of biomaterials is based on composition (animal or human tissue, metals, polymers, ceramics or composites) or on biological reactions after implantation (bio-inert, bio-tolerant or bio-active). Depending on location and function biomaterials have to meet requirements with respect to durability (artificial joints), fixation (total hip prosthesis), flexibility (artificial ligaments), solubility (suture wire) and stiffness (plates and screws). The development of biomaterials is in full swing, focussing on the decrease of wear and the increase of durable fixation of artificial joints, and the induction of cells to form bone and cartilage tissue.

[Ophthalmological applications for biomaterials]
Uusitalo, H. (2004), Duodecim 120(16): 2015-9.

[Orthopedic biomaterials]
Sedel, L., R. Nizard, et al. (1995), Bull Acad Natl Med 179(3): 497-505; discussion 505-6.
Abstract: It is very challenging to insure long term security and effectiveness for joint arthroplasties, artificial ligaments, extensive bone replacement and some other orthopaedic biomaterials. How can we predict the long term security and efficacy of such an implant? Only an interdisciplinary approach can provide a satisfactory answer. The surgeon must define the needs, he must find the appropriate surgical techniques and conduct the clinical trial. The material scientist must elaborate safe and secure materials with regards to their biotolerance and mechanical resistance. This has to be performed in close connection with the biomechanics lab. Biomechanic Science must predict the expected stresses. It has to design special simulator to quantify in vitro material toughness, wear characteristics, lubrication, behaviour and surface deformation. Biological and mechanical standardized tests have to be carried on. Then it is possible to conduct a clinical trial, prospectively in comparison to another already developed material. Clinical studies could serve to measure efficacy and radiological modification. After failure, it is possible to analyse retrieved specimen, to measure the material degradation in real environment, to perform biological studies on retrieved tissues i.e.: macrophagic activities, tissue response, bone ingrowth, inflammatory or immunological reaction. For more than twenty years we worked on alumina against alumina total hips. The idea was to develop a low debris system to enhance long term longevity of the prosthesis. The Charnley design has proven its effectiveness for more than fifteen years, but polyethylene wear is responsible for late failures. This is specially crucial for young patients, male sex and high activity level patients. At the beginning, biological studies and mechanical tests were performed, it appeared that the biological tolerance of alumina ceramic was excellent, the fracture toughness was adequate, but there were some problems related to alumina fixation in the body and also alumina head fixation on metallic stem. Alumina material improved with time. It was possible to diminish the fracture risks and to increase the safety. Parallel information from the first period was used to increase the material quality, the surgical techniques and also to define indication in the use of such material. It is now clear and it also has been published that alumina against alumina system has proved to be as safe as Charnley total hips. It has been proved to give better results in the young age population. Then it is now possible to operate on very young patients, to allow these patients to perform heavy work, sports and regular daily activity for their demand.(ABSTRACT TRUNCATED AT 400 WORDS)

[Ossicular reconstruction with autograft in type III]
Desaulty, A., S. Shahsavari, et al. (2005), Rev Laryngol Otol Rhinol (Bord) 126(1): 19-23.
Abstract: OBJECTIVE: The prostheses known as biocompatible are usually proposed for columellar repair in absence of stapes but at which cost and which long-term tolerance? It appeared useful to study the possibilities of autograft ossicular reconstruction (incus and cortical bone) in absence of suprastructure of the stapes. MATERIAL AND METHODS: Retrospective study for 82 operated patients for cholesteatoma with lysis of the cruras of the stapes. Columellar repair was obtained by prosthesis, columella of cortical mastoid bone, and more often autograft of incus (54 cases). The technique of Autogreffe Tympanum-Cartilage-Os-Platinum (ATCOP) (Autograft Tympanum-Cartilage-Bone-Footplate is described: tympanic repair by fascia and cartilage from the concha is made at the first surgical step. Type III ossiculoplasty is performed at the second look. The distance tympanum-footplate is then lower than 6 mm and the body of the incus, preserved as a spare ossicle in the mastoid, has a sufficient length to be interposed in between new drum and footplate. RESULTS: 78% of the patients have final air bone gap less or equal than 30 decibels. The average post op air bone gap is 23 decibels with incus while it was 42 decibels before surgery. Average gain is 19 decibels. The cost of autograft is null and tolerance is excellent. CONCLUSION: Patient's incus is usable in type III ossiculoplasty thanks to a cartilage graft of the tympanic membrane. Patient's ossicle is a material of choice for columellar repair even in absence of the suprastructure of the stapes. Prostheses in biomaterial appear justified in case of absent or destroyed incus.

[Ossiculoplasty with KURZ titanium prosthesis]
Nguyen, D. Q., N. Morel, et al. (2005), Ann Otolaryngol Chir Cervicofac 122(4): 187-93.
Abstract: OBJECTIVES: Report the functional and anatomic results of ossicular reconstruction by titanium prosthesis. MATERIALS AND METHODS: Retrospective chart reviews were performed for 111 patients who had undergone titanium ossicular implants between November 1998 and 2002 (61 PORP, 50 TORP). The anatomical and audiometric data were analyzed on average at 3 and 20 months. RESULTS: At 20 months, the improvement of air-bone-gap mean was 12.7 dB with better results at low frequencies. The global success rate was 66% (PORP 77%, TORP 52%). It decreased significantly in the open techniques. Extrusion rate was low (2/111) and the labyrinthization rate was 3.6%. Twenty patients required a surgical revision (18%). In 9 patients, the prosthesis was too short. At long-term follow-up, the gains were stable in 60 patients, improved in 32 patients and worsened in 19 patients. CONCLUSION: The success rate is higher in the group of the PORP with the closed technique. The stability of the TORP in open technique still remains problematic. In all cases, the risk of extrusion requires a large cartilage graft recovering the plate of the prosthesis. The high rate of luxation (9/111 prosthesis too short) has led us to increase slightly the length of the prosthesis (+1.22 mm mean).

[Our experiences with nephrectomy with special emphasis on using biocompatible materials]
Szabo, Z., Z. Domjan, et al. (2005), Magy Seb 58(2): 125-8.
Abstract: We performed 43 open partial nephrectomies with different indications between 1996 and 2004, most of them (29) for renal cancer. We used different types of biocompatible materials for haemostasis. We describe our own recommendations and what is described in literature.

[Pathophysiology of infection on orthopedic biomaterials]
Ader, F. and L. Bernard (2005), Presse Med 34(7): 533-6.
Abstract: Orthopedic biomaterials are foreign bodies and the molecular architecture of their surfaces provides a point of attachment for bacteria. This adherence is made possible through the interaction of the protein interface and the bacterial adhesins. Bacterial colonies use slime and biofilm as means of protection. The development of bacteria towards a reversible state of stationary growth or microcolony variants permits their survival. Microparticles released by biomaterials cause the chronic inflammation associated with the aseptic loosening of prostheses. Some bacterial sub-populations develop transitory resistance to bactericidal antibiotics in the presence of these materials.

[Percutaneous injection of bone biomaterials]
Leclet, H. and G. Pasquier (1993), Rev Rhum Ed Fr 60(4): 299-304.

[Peri-implant enzyme activities and mineralization in bone tissue after implantation of bioactive vitroceramics--a method for biomaterial testing of hard-tissue substitutes. 1. Establishment and representation of the method]
Reichelt, H., S. Kohler, et al. (1987), Z Exp Chir Transplant Kunstliche Organe 20(2): 67-74.
Abstract: A method for testing the bioactivity of hard tissue implants is described by analysis of the periimplantary enzyme activities of the alkaline and the acid phosphatase in the femur of rats. Bioactive materials cause an increase of the activity of the alkaline phosphatase in the periimplantal bone tissue. An increase of the activity of the acid phosphatase is a measure for the biodepressive effect of the implant material.

[Peri-implantation enzymes and mineralization in bone tissue after implantation of bioactive vitroceramic material--a method for biomaterial testing for hard tissue substitutes. 2. Results of studies of vitroceramics and their modification by the admixture of metal oxides]
Reichelt, H., S. Kohler, et al. (1988), Z Exp Chir Transplant Kunstliche Organe 21(2): 71-84.
Abstract: The activities of the alkaline and the acid bone phosphatases as well as the concentrations of calcium and phosphorus were measured in the periimplantal tissue of the rat femur bone after implantation of the vitroceramic Ap 40, the metal oxide stabilized vitroceramics Ap 40 A and Ap 40 Z, as well titanium after 2, 10, and 15 weeks. The incorporation of the vitroceramic Ap 40 turns out like a primary bone fracture healing. The implants Ap 40 A and Ap 40 Z are a compromise with a higher stability and the osteogenesis induced effect is preserved, but is belated in contrast to Ap 40.

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