Wear of conventional and cross-linked ultra-high-molecular-weight polyethylene acetabular cups against polished and roughened CoCr femoral heads in a biaxial hip simulator.

The wear of acetabular cups made from conventional gamma-sterilized, and electron-beam cross-linked ultra-high-molecular-weight polyethylene was studied with a biaxial hip wear simulator. The femoral heads were either polished or roughened so that they represented the type of roughening and the value of surface roughness (R(a) = 0.14-0.18 micro m) observed in the roughest explanted femoral heads. The lubricant was diluted calf serum, and the test length 3 million cycles. The mean wear rate and standard deviation of conventional polyethylene cups against polished and against roughened heads was 11.6 +/- 0.07 and 64.4 +/- 10.1 mg per 1 million cycles, respectively. The latter value closely corresponds to that measured from explanted Charnley prostheses. Against polished heads, cross-linked polyethylene cups showed net weight gain, whereas against roughened heads, their mean wear rate was 2.4 +/- 0.3 mg per 1 million cycles. The mean equivalent circle diameters of polyethylene wear particles produced in the above four categories were: conventional/roughened 0.32 micro m, cross-linked/roughened 0.29 micro m, conventional/polished 0.28 micro m, cross-linked/polished 0.23 micro m. The size ranges and shapes were close to those seen in particles isolated from tissue samples. In conclusion, the tests indicated that electron-beam irradiation effectively reduces the harmful polyethylene wear particle production in total hip arthroplasty.

被引量：13 发表：2002

Response of normal female human osteoblasts (NHOst) to 17beta-estradiol is modulated by implant surface morphology.

Titanium (Ti) surfaces with rough microtopographies enhance osteogenic differentiation, local factor production, and response to osteogenic agents in vitro and increase pullout strength of dental implants in vivo. Estrogens regulate bone formation, resorption, and remodeling in females and may be important in implant success. Here, we tested the hypothesis that estrogen modulates osteoblast response to implant surface morphology. Primary female human osteoblasts were cultured to confluence on three Ti surfaces (pretreatment, PT - R(a) 0.60 microm; sandblasted and acid-etched, SLA - R(a) 3.97 microm; and Ti plasma-sprayed, TPS - R(a) 5.21 microm) and treated for 24 h with 10(-7) or 10(-8) M 17beta-estradiol (E(2)). Cell number decreased with increasing surface roughness, but was not sensitive to E(2). Alkaline phosphatase specific activity of isolated cells and cell layer lysates was lower on rough surfaces. E(2) increased both parameters on smooth surfaces, whereas on rough surfaces, the stimulatory effect of E(2) on alkaline phosphatase was evident only when measuring cell layer lysates. Osteocalcin levels were higher in the conditioned media of cells grown on rough surfaces; E(2) had no effect in cultures on the plastic surfaces, but increased osteocalcin production on all Ti surfaces. TGF-beta1 and PGE(2) production was increased on rough surfaces, and E(2) augmented this effect in a synergistic manner; on smooth surfaces, there was no change in production with E(2). The response of osteoblasts to surface topography was modulated by E(2). On smooth surfaces, E(2) affected only alkaline phosphatase, but on rough surfaces, E(2) increased levels of osteocalcin, TGF-beta1, and PGE(2). These results show that normal adult human female osteoblasts are sensitive to surface microtopography and that E(2) can alter this response.

被引量：23 发表：2002

Bioethics and applied biomaterials.

被引量：1 发表：1987

Protein adsorption and platelet attachment and activation, on TiN, TiC, and DLC coatings on titanium for cardiovascular applications.

The hemocompatibility of a TiN/TiC/diamond-like carbon (DLC) multilayer structure, deposited on titanium substrates for use as coatings for a heart valve prosthesis, has been studied through the adsorption of blood proteins and the adhesion and attachment of blood platelets. All of the surfaces were characterized by stylus profilometry and water contact angles. The adsorption of albumin and fibrinogen to the surfaces was assessed using the Amido Black assay, whereas platelet attachment was studied by scanning electron microscopy and quantified using stereological techniques. The degree of platelet spreading on the surfaces was seen to correlate with differences in surface energy, indicated from contact angle measurements. The greatest spreading was seen on the more hydrophilic surfaces. When studying protein adsorption to the surfaces, no correlation could be determined between contact angle results and levels of adsorption, although the most hydrophilic surfaces did appear to promote greater amounts of fibrinogen adsorption. Thrombus formation was observed to some degree on all of the surfaces, with the exception of the DLC coating. This coating also promoted less spreading of platelets than the other surfaces. The good hemocompatibility of the DLC coating is attributed to its hydrophobicity and smooth surface, resulting in a higher ratio of albumin to fibrinogen than any of the other surfaces.

被引量：21 发表：2000

The fallacy of evaluating biomaterial wear-rates with water as lubricant: a hip simulator study of alumina-PTFE nd CoCr-PTFE combinations.

被引量：1 发表：1998