Because of its properties was first used in Surgery in the 1950’s and it is currently accepted by medical professionals as material of choice for prosthetics, fixation, instrumentation.
Titanium is in fact absolutely inert in the human body, immune to attack from bodily fluids (due to its protective oxide film), compatible with bone growth (due to its high dielectric constant, titanium has the property that it can bind to bone and living tissue), strong and flexible (titanium is 56% lighter than stainless; yield strength double, modulus of elasticity and coefficient of thermal expansion very similar to human bone, reducing the potential for implant failure) leading titanium to be "the most biocompatible of all metals".