HIPed Material Research Articles

Elementary Study of Modifying UHMWPE with Schiff Base Copper Complex for the Use as an Artificial Hip Joint Material

Elementary micro-tribological test for UHMWPE modified with 15 wt% of Schiff base copper complex (Cu(II) chelate of bissalicylaldehyde-ethylenediamine rubbed by titanium alloy showed that a reduction of 20% friction coefficient when compared with the pure UHMWPE/titanium alloy pair under the condition of dry friction. Under a simulating loading level of an artificial hip joint, the highest frication coefficient of the modified UHMWPE pairing with steel was 15% lower than its pure UHMWPE/steel pairing counterpart. Furthermore, wear of the modified UHMWPE was very mild almost without any sign of worn debris even being run for a sufficiently long period, while the pure UHMWPE could run only for a very short period. Test results confirmed that the Cu(II) chelate of bissalicylaldehyde-ethylenediamine modifying UHMWPE was able to reduce friction, wear and debris during application. Besides excellent tribological characteristics, good biocompatibility of the modified UHMWPE was also demonstrated by a cell toxicity test in vitro. T Consequently, attempts to develop this modified UHMWPE for artificial joint is obviously beneficial.

The adsorption and lubrication behavior of synovial fluid proteins and glycoproteins on the bearing-surface materials of hip replacements

The selectivity of synovial fluid protein adsorption onto ultra-high molecular weight polyethylene (UHMWPE) and alumina (Al 2O 3), and in particular the ability of glycoproteins to adsorb in the presence of all the other synovial fluid proteins, was investigated by means of fluorescence microscopy and gel electrophoresis (SDS-PAGE). The non-specific nature of protein adsorption from synovial fluid indicated that the lubrication of artificial hip-joint materials may not be attributable to a single protein as has been frequently suggested. The friction behavior of polyethylene (PE) sliding against Al 2O 3 in solutions of bovine serum albumin (BSA), alpha-1-acid glycoprotein (AGP) and alpha-1-antitrypsin (A1AT) was investigated by means of colloidal probe atomic force microscopy. BSA was shown to be a poorer boundary lubricant than the phosphate buffered saline used as a control. This was attributed to denaturation of the BSA upon adsorption, which provided a high-shear-strength layer at the interface, impairing the lubrication. Interestingly, both the glycoproteins AGP and A1AT, despite their low concentrations, improved lubrication. The lubricating properties of AGP and A1AT were attributed to adsorption via the hydrophobic backbone, allowing the hydrophilic carbohydrate moieties to be exposed to the aqueous solution, thus providing a low-shear-strength fluid film that lubricated the system. The amount of glycoprotein adsorbed on hydrophobic surfaces was determined by means of optical waveguide lightmode spectroscopy (OWLS), allowing conclusions to be drawn about the conformation of the glycan residues following adsorption.

Wear of the artificial hip joint material under lubrication

AbstractA study of wear properties of hip‐replacement materials, namely high‐nitrogen stainless‐steel femoral heads and ultra‐high molecular weight polyethylene (UHMWPE), was conducted in a non‐conforming apparatus using various liquid lubricants. The liquids used were normal saline solution, sodium azide solution, pure ethanol, aqueous hyaluronic acid and aqueous hyaluronic acid/cholesterol and cholesterol palmitate liquid crystal lubricant. Saline solution proved to be unsuitable as a lubricant while sodium azide that was used as a bactericide provided some evidence of mixed lubrication. A bactericide was included to overcome degradation. The aqueous hyaluronic acid exhibited cushion form lubrication as evidenced by retention of the original polymer surface features within the wear indent. Cholesterol addition showed little improvement on the wear properties but massively increased the bacterial activity. Again, inclusion of a bactericide was necessary. Liquid crystal lubricant significantly reduced wear and the atomic force microscope (AFM) showed that the liquid crystal formed protective layers on the counter face surfaces. The sub‐surface of the polymer possessed plastic creep under load but low adhesive wear was present. There also was an absence of sub‐micron polymer debris. It was concluded that a dramatic reduction in wear could be achieved by incorporation of liquid crystal lubricant in hip‐replacement elements. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.

A New Simulator for Bio-Tribological Study

A new bio-tribological simulator system was designed and built for basic wear tests on artificial hip joint materials and for common tribological studies applications. The module of hip joint simulator is consisted of Flexion and Extension (FE), Abduction and Adduction (AA) and Internal and External Rotation (IER). Preliminary tests were done with a 28 mm CoCrMo femoral head and a Ultra High Molecular Weight Polyethylene (UHMWPE) cup. Results showed that the wear rate was close to the clinical one. A frequency control system and a heating system were developed to offer a wide range of rotation frequency and temperature so as to provide proper experiments. In the Pin-on-Disk (POD) part, eight precision-made pins were generated and an advanced computer system was built up to measure the friction coefficient of the tests samples.

4105 変動荷重型3自由度シミュレータを用いた人工股関節用材料の摩擦特性評価(J30-2 人機能支援の工学(2),ジョイントセッション,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

Total joint arthoroplasties are done for the elderly persons who have difficulty at their daily lives because of their disease of joint, and so on. We developed the simulator of artificial hip joint which can generate alternating load, and 3 degrees of freedom with simple construction, and change the pattern of load and the maximum load for the purpose of evaluating the frictional properties of Artificial hip joint materials Ti-6A1-4V, and ultra high molecular weight polyethylene (UHMWPE) used for them. By sliding which was added the constant load and the alternating load, as for the wear of UHMWPE, latter was greater than former. But, as for the frictional coefficients, both of them were nearly equal. And it was shown that, at the beginning of sliding, the frictional coefficients were inclined to be reduced, and that, at the end of sliding, the frictional coefficients were inclined to be stable.

Erratum to “Wear of artificial hip joint material” [Chem. Eng. J. 112 (2005) 137–144

Erratum to “Wear of artificial hip joint material” [Chem. Eng. J. 112 (2005) 137–144

Neutron irradiation effect on mechanical properties of SS/SS hip joint materials for ITER shielding blankets

In support of the ITER blanket fabrication, this study clarified the neutron irradiation effect on the tensile properties of HIP joints using stainless steels and the effect of surface roughness (Ry) at the joint boundary on tensile properties of HIP joints. Three different types of joints (type-A: Ry = 1 μm, type-B: Ry = 10 μm and type-C: Ry = 30 μm) were prepared and irradiated up to 1.5 dpa at 240–250 °C. It was determined that the tensile properties of HIP joints were almost the same as those of stainless-steel base material irrespective of neutron irradiation. The difference in surface roughness condition and total elongation of irradiated type-C joints was smaller than that of the other types of joints, but the tensile strength of HIP joints was not changed by the surface roughness condition. This study confirmed that the tensile strength of HIP joints by the standard HIP condition was almost the same as that of the base material after neutron irradiation, and that it is possible to alleviate the requirement on surface roughness condition for HIP joining as part of the ITER blanket fabrication.

Tribological Properties of Artificial Hip Joint Material Coated with DLC Thin Film in the Simulated Body Environment

Tribological Properties of Artificial Hip Joint Material Coated with DLC Thin Film in the Simulated Body Environment

Wear of artificial hip joint material

A non-conforming apparatus was devised to study the wear properties of hip replacement materials (stainless steel femoral head and mainly ultra-high molecular weight polyethylene, UHMWPE). The analysis was by wear depth and various types of microscope examination of the worn surfaces. The importance of proper femoral head surface conditions is emphasized. The dry worn debris matched that retrieved from revision surgery indicating the in vivo wear was without fluid lubrication. A qualitative model is presented to explain the observed wear and wear rate profiles. The long-term wear was within a narrow range that matched in vivo results. Tests on polyetherether ketone (PEEK) polymer indicated that it had superior wear properties to UHMWPE.

Wear Simulation of Alumina-on-Alumina Prosthetic Hip Joints Using a Multidirectional Motion Pin-on-Disk Device

The wear of a state-of-the-art implant alumina against itself was studied with a circularly translating pin-on-disk (CTPOD) device, a wear simulator for prosthetic hip joint materials. The direction of sliding changed continually relative to the pin, preventing erroneous uniaxial grooving typical of ordinary pin-on-disk devices. The dominating wear mechanism was mild abrasion manifested as a relieflike surface, which agreed with clinical findings. The wear factor ranged from 1 × 10−8 to 6 × 10−8 mm3/(N·m). The CTPOD device, validated earlier for ultrahigh molecular weight polyethylene, was shown to be the first simple wear test device to produce wear similar to that known to occur clinically in alumina-on-alumina total hip prostheses.

Effect of standard heat treatment on the microstructure and mechanical properties of hot isostatically pressed superalloy inconel 718

Ni–Fe base superalloy, Inconel 718, was processed through powder metallurgy (P/M) hot isostatic pressing (HIP) route. In order to balance the strength and ductility, the HIPed material was given the standard heat treatment, viz. solution treatment at 980 °C for 1 h/water quenched (WQ) to room temperature and a two-step ageing treatment consisting of 720 °C for 8 h/furnace cooling (FC) at 55 °C h −1 to 620 °C and holding at 620 °C for 8 h before air cooling (AC) to room temperature. Optical microscopy and scanning electron microscopy (SEM) studies on the heat treated alloy have shown a homogeneous microstructure with fine grain size (25 μm) along with the presence of prior particle boundary (PPB) networks. Transmission electron microscopy (TEM) on the heat treated material has revealed the presence of oxides, MC carbides and δ-precipitates at the grain boundaries and a uniform precipitation of fine γ″ and γ′ strengthening phases in the matrix. Tensile and stress rupture tests were performed on the heat treated material. While the yield strength (YS) and ultimate tensile strength (UTS) of the HIPed and heat treated alloy at room temperature and 650 °C were comparable to those of conventionally processed wrought IN 718, its ductility was lower. The stress rupture life of the HIPed alloy improved marginally due to heat treatment and met the minimum specification requirement of life hours but the rupture ductility was found to be inferior to that of the wrought material. The fractography of the failed samples has revealed the transgranular ductile mode of fracture in the as-solution treated alloy, while intergranular mode of failure with the decohesion of PPBs occurred more predominantly in the aged condition. This change of fracture mode with ageing treatment shows the ductility dependence on the relative strength of the matrix and PPBs. The TEM studies on the deformed alloy have revealed that the brittle oxides and carbides at the prior particle boundaries coupled with the fine γ″ and γ′-precipitates in the matrix are responsible for low ductility at 650 °C. The investigations of the present study have led to better understanding of the structure–property relationships in HIP+heat treated alloy 718 and suggest that the standard heat treatment recommended for wrought IN 718 is not suitable for HIPed alloy and has to be modified to realise optimum properties.

1214 DLC 薄膜を被覆した人工股関節材料の擬似生体環境における摩擦摩耗特性に関する研究

A study has been carried out to examine the feasibility of diamond-like carbon (DLC) film prepared on Co-Cr alloy by the hot filament method, as an enhanced wear resistant coating for artificial joints made of Co-Cr alloy/UHMWPE sliding pairs. The wear resistance of DLC coated Co-Cr alloy/UHMWPE sliding pair shows much improvement over the uncoated Co-Cr alloy/UHMWPE sliding pair in a salt solution 1%. However, DLC film was brittleness by a salt solution 1%, and adhesive strength also declined. It is possible that a DLC film can expect application to a artificial hip joint material.

Properties of HIPed stainless steel powder

In the current design of ITER primary wall, 316LN stainless steel is the reference structural material. Austenitic stainless steel is used for water-cooling channels and structures. As material data on hot isostatic pressed (HIP) 316LN were not available in open literature and from powder producers, the main properties of unirradiated samples have been measured in CEA/CEREM. Fully dense material without any porosity is obtained when appropriate HIP parameters are applied. Microstructural examination and mechanical properties are confirmed that the HIPed 316LN material is equivalent to a very good fine-grain, isotropic and uniformly forged 316LN. Moreover, ultrasonic inspection showed that this fine and uniform microstructure produced a remarkably low noise, which allow the use of transverse waves at very high frequencies (4 MHz). Defects undetectable in forged material will be easily detected in HIPed material.

Twenty years of Sulzer experience with artificial hip joint materials.

This paper reviews the development of hip prostheses over the past 20 years with particular reference to the materials employed. The material properties required are discussed and the alloys used in different designs of prostheses are described.