Intramedullary nails.
An example of the element Titanium

"Titanium has become a preferred material for Orthopedic implants over the past 10-15 years because of a number of its inherent properties. It is inert in the body, and has sufficient strength to support the mechanical loads (assuming proper design and size of the implant). It is also very resistant to fatigue failure - that is, it can undergo many (millions) of cycles of mechanical loading without failure - a property that is extremely important in an Orthopedic implant that will be subjected to a million cycles of loading a year. Most Orthopedic titanium implants are actually an alloy of titanium with small amounts of aluminum and vanadium, as pure titanium implants are somewhat brittle and have a higher rate of fracture. Titanium alloy is less brittle, and holds up quite well."
"As to why the implants you have are not in someone's body, they are not defective; they were actually in the operating room and taken out of their sterile packaging in anticipation of being implanted, but were for one reason or another not used. In some cases, the devices were implanted, but found to be too long or too short, and were then replaced with a correct sized implant. We are not allowed to re-use devices that have been implanted and removed, as there is no feasible way to ensure that the stresses of implantation have not altered the mechanical properties of the device. So they become very expensive junk. (Any implant that was removed from a patient was thoroughly cleaned and then sterilized before it left the OR). Other devices may have been removed from their packaging, but not implanted because the surgeon changed his/her mind about the size or decided to use a slightly different implant before actually putting in the patient. Depending on the implant, re-sterilization in the hospital may not be practicable - more expensive junk."
"These intramedullary rods or nails are placed inside the intramedullary canal (marrow cavity) of long bones like the femur or tibia to stabilize fractures of these bones until they heal."