Orthopaedic Alloys Research Articles

X-ray photoelectron study of surface layers on orthopaedic alloys. I. Ti–6Al–4V (ASTM F-136) alloy

It is now widely acknowledged that the stability, performance, and life of prostheses fabricated from metallic materials are directly related to the compositional details of the layers formed on the surfaces of these components at the time of implantation. The thrust of the present investigation is thus the use of angle-resolved x-ray photoelectron spectroscopy for the identification of the differences in composition and thickness between the layers formed on the surface of a Ti–6Al–4V alloy specimen following exposure for 1 h to either laboratory air or wet steam.

X-ray photoelectron spectroscopy study of surface layers on orthopaedic alloys. II. Co–Cr–Mo (ASTM F-75) alloy

The differences and similarities between the compositional details of the layer formed on the surface of a Co–Cr–Mo alloy specimen when exposed for 1 h to laboratory air or wet steam are identified. An estimate of the thickness of each of these layers is also obtained.

Ion Implantation as a Tool for Improving the Properties of Orthopardic Alloys

ABSTRACTIon Implantation is emerging as a specialized surface treatment method by which orthopaedic alloys can be doped in order to modify for corrision, fatigue and wear properties.In this paper alterations in the corrosion and fatigue resistance of 316LVM stainless steel and Ti 6A1-4V ELI titanium alloy are considered. The effect of various variables was investigated; ion species, flux, accelerating voltage.Changes in corrosion resistance were monitored by performing anodic polarization studies in deaerated 0.1M NaCi solution at 22°C. The most effective species were found to be tantalum and boron for improvements to stainless steel.Fatigue properties were investigated using a Wohler type rotating bend test. Preliminary results show that nitrogen ion implantation improved the fatigue life for the steel but not the titanium alloy. Indications were found to suggest that time since implantation affect the fatigue properties.

Fretting corrosion in orthopaedic alloys.

Fretting corrosion, a mechanical-chemical phenomenon, most often occurs at screwhead-plate countersink junctions of internal fixation devices. An apparatus was constructed which would simulate the conditions of fretting corrosion in vivo. Fretting corrosion was studied as a function of the number of cycles and the solution in which the fretting occurred. The solutions studied were 0.9% physiological saline and a saline plus 0.5% albumin solution. The implant materials tested were Co-Cr-Mo alloy, 316L stainless steel, and Ti-6A1-4V alloy. The results demonstrated that weight loss increased with the number of fretting cycles but reached a plateau where further weight loss was negligible. Co-Cr-Mo alloy showed less weight loss than 316L stainless steel at any number of cycles. Weight loss for Ti-6A1-4V alloy was similar to Co-Cr-Mo alloy although marked abrasion was noted. All of the materials showed a marked decrease in weight loss when tested in the saline plus albumin solution as compared to the saline only solution.

A comparative evaluation of the wear of ultra-high molecular weight polyethylene abraded by Ti-6Al-4V

The study was initiated to assess the suitability of Ti-6Al-4V as a metal which articulates against Ultra High Molecular Weight (UHMW) polyethylene in total joint applications. The wear surfaces of Ti alloy were prepared to different levels of surface roughness and the effect of various surface chemical treatments were examined. A specially designed annular contact laboratory wear tester was developed to provide the surface loading and articulation. Comparative tests were also performed using 316 LVM stainless steel and Co-Cr-Mo alloy metallic wear components. All annular contact wear tests were performed in mammalian Ringer's solution environments and were evaluated using standard statistical techniques. Scanning electron microscope (SEM) analysis of the wear surfaces indicates the formation of a polyethylene transfer film on all metal surfaces. The surface of the UHMW polyethylene samples after testing was considerably rougher than the original articulating metallic surface; the transfer film on the metal surfaces was responsible for this. It was concluded that Ti-6Al-4V is satisfactory for total joint replacement when used in combination with UHMW polyethylene. Proper surface preparation may allow lower rates of wear than conventional orthopaedic alloys.

Survey of materials for hard‐tissue prosthesis

AbstractThe properties of the three main classes of orthopedic alloys (316L steel, Co‐Cr alloys and titanium) are discussed, while all show good general corrosion resistance, the 316L steel have a tendency toward crevice corrosion. Fatigue fracture due to poor design and fabrication defects is discussed. A summary of some problems associated with the evaluation of tissue response is presented. Finally, a review of several new trends toward achieving tissue adhesion is presented.