Papers by Keyword: Hip Prostheses

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Authors: Mohd Bin Sulaiman Hafis, R.N. Farahana, Mohd Jamir Mohd Ridzuan, S. Siti Mahani
Abstract: Wear generated by the presence of friction on hip joint contact surfaces can cause debris, which may lead to loosening and failure of the hip prostheses. The objective of this study is to examine the limiting friction coefficient of the hip joint using Finite Element (FE) method. The hip joint model was developed to represent the contact surfaces between femoral head and inner socket, and the contact surfaces between inner socket and acetabular cup. The measured angle from 0° to 15° was applied to the inner socket for normal walking condition. The maximum contact pressure on the acetabular cup surface was found at the position angle of 10°. Therefore, further examination was carried out and the results showed that the highest friction coefficient of 0.4 was determined.
Authors: P.A.S. Wrege, C.A. Fortulan, B. de M. Purquerio
Authors: Nere Garmendia, Leire Bilbao, Roberto Muñoz, L. Goikoetxea, Ainara García, Izaskun Bustero, Beatriz Olalde, Nerea Garagorri, Isabel Obieta
Abstract: Carbon nanotubes could avoid the crack propagation and enhance the toughness of the ceramic material used for prostheses applications. So nanozirconia partially coated carbon nanotubes have been obtained via hydrothermal synthesis of zirconia nanoparticles in presence of multiwall carbon nanotubes. The as covered nanotubes should have a better wettability in the ceramic matrix and improve the dispersion of the CNTs in the nanocomposite, which results in a new ceramic biomaterial with a longer lifetime and better reliability. The obtained product has been structurally characterized by several techniques such as FTIR, XRD, SEM, AFM, EELS, XPS and TGA. The citotoxicity of the sintered product was studied by the change in the pH and ICP-AES in in-vitro biocompatibility tests.
Authors: Liliana Laura Badita, Gheorghe Ion Gheorghe
Abstract: The main purpose of this project was to study and improve the tribological characteristics of hip and knee prostheses in order to use them for a longer period of time. We conducted a thorough investigation of components of hip and knee prostheses. We started with the study of hip prostheses obtained after revision surgery. In this paper we present some experimental results about the scratch resistance of Ti6Al4V alloy and Co-Cr alloy femoral heads coated by physical vapor deposition (PVD) with TiN and Co-Cr-Mo, respectively. Visual analysis and optical microscopy analysis of prosthetic components revealed numerous multi-directional scratches, deeper or less deep, frosted the surface in the geometric place of action of the resultant force application point, microcorossion and peeling of the coating on the prosthetic femoral heads made of CoCr coated with CoCrMo by PVD method. Scratches, corrosion, peeling and bio-tribo-corrosion of titanium nitride (TiN) coating from the Ti6Al4V femoral heads surface were also observed. Using atomic force microscopy (AFM), topographic characterization at nanometric scale of these surfaces was realized. Surface topography parameters such as minimum and maximum height, average roughness, and surface asymmetry were derived. It resulted that under the deposition there is a more veiled area. Roughness was used as an indicator of damage to the femoral head to obtain information on the variation in height from one point to another. AFM analysis revealed a dramatic increase in average roughness (Ra) of femoral heads compared to the maximum value of 0.05 μm provided under ISO 7206-2. From all these studies it was noted the need for a resistant prostheses, with anticorrosive composition and high mechanical properties. Among the numerous methods to reduce wear we realized thin films (biocompatible nanomaterials) deposition of TiN on 316L SS steel substrates by pulsed laser deposition method (PLD), to improve overall performance and, in particular, mechanical prosthesis of hip prostheses structures. The results obtained leads to the conclusion that PLD technique is a good method to make amorphous and crystalline films, dense and porous by controlling the laser system conditions. All parameters can be controlled and varied to identify the optimum structures and to obtain thin layers.
Authors: Yen Shuo Liao, Mark Hanes, J.Craig Fryman, Mark DiSilvestro
Abstract: This study evaluated the wear performance of cobalt-chromium, zirconia and alumina/zirconia composite heads against moderately crosslinked ultra-high-molecular-weight polyethylene liners under different temperature conditions. A temperature control unit was utilized to allow direct cooling/heating the head components at 4, 20, 37 and 45 °C in addition to the conventional no temperature control method. Results showed that the polyethylene wear was affected by the coolant temperature. The CoCrMo and the alumina/zirconia groups had similar wear rate without temperature control, however, the CoCrMo group generated 50% more wear than the alumina/zirconia group did when the coolant temperatures were above 20 °C. The zirconia group had the lowest wear rate of the three groups in all temperature conditions. The monoclinic phase content of the zirconia heads were about 0.2 M% before the test and 6.0 M% after the test, while the X-ray diffraction remained similar before and after the test in alumina/zirconia composite heads. The current study was able to reproduce the phase transformation of zirconia ceramics as reported in some clinical retrieval reports. A temperature control feature is recommended in a wear study in order to better simulate implant wear performance under the physiological condition in human body.
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