Ion Leaching from Implantable Medical Devices

Abstract

Abstract. Implantable medical devices must be able to withstand the corrosive environment of the human body for 10 or more years without adverse consequences. Most reported research and development has been on developing materials and devices that are biocompatible and resistant to corrosion-fatigue, pitting, and crevice corrosion. However, little has been directly reported regarding implantable materials with respect to the rate at which they generate soluble ions in-vivo. Most of the biocompatibility studies have been done by examining animal implants and cell cultures rather than examining the rate at which these materials leach ions into the body. This paper will discuss what is currently known about the rate at which common implant materials (such as stainless steels, cobalt-chromium alloys, and nitinol) elute ions under in vitro conditions, what the limitations are of such data, and how this data can be used in medical device development.

Corrosion of Shape Memory and Superelastic Alloys

“…Although such tests are critical for developing safe medical devices, they provide little help in understanding what it is about a particular material or surface condition that is affecting cytotoxicity or immunological response [119,120]. The rate at which various alloy elements go into solution, the metal ion leaching rate, is likely to have a direct bearing on the toxicity, biocompatibility, and immunological response of a medical device.…”

Fatigue Properties of Superelastic Ti-Ni Filaments Used in Braided Cables for Bone Fixation

“…A large number of studies have been conducted to evaluate the impact of alternating strain on the fatigue life of Ti-Ni superelastic alloys [2][3][4][5], but only a few focused on the impact of the mean strain [6][7][8][9][10]. While all of aforementioned studies agree that the higher the alternating (oscillating) strain, the shorter the fatigue life, there is no consensus regarding the mean strain influence [11].…”