Cytotoxicity of Metal Ions Released from Nitinol Alloys on Endothelial Cells.

Most implantable medical devices are expected to function in the body over an extended period of time. Therefore, immersion tests under simulated conditions can be useful for assessing the amount of metal ions released in situ. In this investigation, dissolved ions from as-received binary and ternary Nitinol alloys in cell culture media were periodically measured under static and dynamic conditions. Endothelial cells were grown in aliquots of culture media obtained and the effect of dissolved ions on cell proliferation and viability of endothelial cells (HUVEC) was studied by cytotoxicity assays. The concentration of metal ions in the media was measured by inductively coupled plasma mass spectrometry.

Surface modifications of nitinol.

Nitinol (an acronym for the Nickel-Titanium Naval Ordnance Laboratory) has been extensively explored as an implant material for the medical industry. The potential problem with Nitinol implant devices is the release of Ni in the human body, which has stimulated a great deal of research on surface modifications and the application of coatings. This paper presents a comprehensive review of various treatments to modify the surface of Nitinol in an effort to inhibit Ni release and to render improved biocompatibility. We discuss the important in-service properties of Nitinol, such as biocompatibility, corrosion resistance, stability, uniformity, and the nature of passivating oxides produced by passivation, electropolishing, magnetoelectropolishing, ion beam implantation, sterilization, and artificial coatings.

The effect of a neck-retaining femoral implant on leg-length inequality following total hip arthroplasty: a radiological study.

The aim of this study was to assess whether a femoral component which retained the neck reduced the incidence of leg-length inequality following total hip arthroplasty. A retrospective review was undertaken of 130 consecutive primary total hip arthroplasties performed between April 1996 and April 2004 using such an implant. There were 102 suitable patients for the study. Standardised pre- and post-operative pelvic radiographs were measured by an independent investigator to the nearest millimetre. The leg-length inequality was reduced from a mean pre-operative value of -0.71 cm to a mean of 0.11 cm post-operatively. Of the 102 patients 24 (23.5%) had an equal leg-length post-operatively, and 95 (93.1%) had a leg-length inequality between -1 cm and 1 cm.