Ultra-high molecular weight polyethylene (UHMWPE) is a common bearing component in total knee replacement (TKR) implants, and its susceptibility to wear continues to be the long-term limiting factor in the life of these implants. This study hypothesized that in TKR systems, a highly cross-linked (HXL) UHMWPE blended with vitamin E will result in reduced wear as compared to a direct compression-moulded (DCM) UHMWPE. A wear simulation study was conducted using an asymmetric lateral pivoting '3D Knee' design to compare the two inserts. The highly cross-linked UHMWPE was aged prior to the testing and force-controlled wear testing was carried out for 5 million cycles using a load-controlled ISO-14243 standard at a frequency of 1 Hz on both groups. Gravimetric measurements of DCM UHMWPE (4.4 +/- 3.0 mg/million cycles) and HXL UHMWPE with vitamin E (1.9 +/- 1.9 mg/million cycles) showed significant statistical differences (p < 0.01) between the wear rates. Wear modes and surface roughness for both groups revealed no significant dissimilarities.

No abstract

Chromia forming ferritic stainless steels (SS) exhibit many desirable qualities for intermediate temperature solid oxide fuel cell interconnect applications. However, with these alloys, there is a need to prevent chromia volatilization and the associated chromium poisoning at the cathode–electrolyte interface, while ensuring low interfacial electrical resistance with the cell electrodes; a need that has generated renewed interest in the development of oxidation resistant, electrically conductive coatings. In the present study, screen printed (Mn,Co)3O4 coatings were applied to a newly developed ferritic SS alloy, Sanergy HT(Cr—21.9%, Ni—0.5%, Mo—0.88%, Nb—0.60%, and Si—0.05%). The oxidation behavior of both the coated alloy and the bare alloy were evaluated at 800°C in air for exposures times up to 1500 h. The oxidation kinetics, investigated using weight gain and scale thickness measurements, exhibited parabolic behavior for the bare alloy. The oxidation behavior of the coated material could not be explained by a single parabolic mechanism. The calculated parabolic thickening rate constants were compared with published data on other ferritic SS alloy compositions.

Multiple factors have been identified as contributing to polyethylene wear and debris generation of the acetabular lining. Polyethylene wear is the primary limiting factor in the functional behavior and consequent longevity of a total hip arthroplasty (THA). This retrospective study reviewed the clinical and radiographic data of 77 consecutive THAs comparing in vivo polyethylene wear of two similar acetabular cup liners. Minimum follow-up was 7 years (range 7–15). The incidence of measurable wear in a group of machined liners sterilized with ethylene oxide and composed of GUR 1050 stock resin was significantly higher (61%) than the compression-molded, GUR 1020, O2-free gamma irradiation sterilized group (24%) (P = 0.0004). Clinically, at a 9-year average followup, both groups had comparable HHS scores and incidence of thigh or groin pain, though the machined group had an increased incidence of osteolysis and annual linear wear rate.