Review Question - QID 214076

One of the main disadvantages of stainless steel is its susceptibility to corrosion, specifically pitting and crevice corrosion.

Pitting corrosion is a form of localized corrosion that leads to the creation of small holes in the metal. This process occurs due to a dissolution of the oxide layer around the implant and results in disruption to the surface of the metal. Pitting corrosion typically occurs in alloys that are protected by a passivating oxide film such as stainless steels, nickel alloys, and aluminum alloys. Crevice corrosion occurs via a similar process and is due to a change in oxygen tensions. Type 316L stainless steel, specifically, is an austenitic stainless steel and contains around 17% Cr, 12% Ni and 2.5% Mo with carbon below 0.03%. Conversely, advantage of stainless steel are its stiffness, fracture resistance and low price.

Srinivasan et al review modularity in femoral components in total hip arthroplasties. They report corrosion at the head-neck taper may be caused by multiple mechanisms (ie, crevice, fretting, galvanic). They conclude junctions of stainless steel necks and CoCr heads were found to be more susceptible to fretting corrosion in all conditions tested (ie, variation in offset, media, and cyclic loading).

Eliaz et al review the corrosion of metallic biomaterials. They report that the surface properties of 316L stainless steel make it highly susceptibility to pitting and crevice corrosion. They conclude that compared to titanium allows, the corrosion potential of 316L stainless steel is more active, resulting in overall higher rates of corrosion.

Incorrect Answers:
Answer 1: The modulus of elasticity of stainless steel is greater than that of cortical bone.
Answer 3: 316L stainless steel is an iron-carbon alloy.
Answer 4: The majority of TKA femoral components are composed of cobalt-chrome alloys.
Answer 5: The modulus of elasticity of stainless steel is less than that of cobalt chrome.