This paper will discuss the key properties of three categories of implant alloys; stainless steels, cobalt-based alloys, and titanium-based alloys, focusing on those properties which make the implant alloys ideal for skeletal implants. An additional focus of the paper will be on any disadvantages possessed by each group of implant alloys.
             Wood was probably the first bioimplant, a sturdy, inert, and readily available material in the older days. But as mankind aged newer materials were discovered, and often created, that were indeed superior. The search for a exceptional implant alloy is one which has laboratories researching and testing different types of alloys for the best combination of strength, durability, corrosion resistance, and other important traits these alloys must possess.
             The first implant metal to be discussed is stainless steel. The one most common stainless steel in use is 316L, grade 2. This particular alloy is mostly iron, chromium, and nickel, though it also contains nitrogen, magnesium, molybdenum, phosphorous, silicon, and sulfur. Most implant quality 316L has at least 62.5% iron, 17.6% chromium, and 14.5% nickel. The implant quality 316L has improved corrosion resistance, structure, and ductility over the commercial quality form of the alloy. An important property of the stainless steel alloy is its high chromium content which fights corrosion by forming an surface oxide. The nickel is added to insure "no delta ferrite", or to combat the impact the chromium, molybdenum, and silicon have in forming ferrite. "No delta ferrite" is a condition where there is no metallic resonance, allowing for the implant to still be safe even when the patient is undergoing an MRI. There is a drawback to the use of nickel in the implant, which in turn means there is a drawback to the implant itself. Somewhere in between 3% and 5% of the population is allergic to nickel. "Nickel causes inf...