Hi srg36, I think implantable orthopedic medical devices is the most highly regulated medical devices in the market. As we learned form the validation process lecture, Validation is to ensure that the medical device meets the user requirements and the intended use, so, for example, validation for a total hip joint replacement requires mechanical testing, which is difficult to pass, because mechanical testing allows the mechanical conditions in the human body to be simulated in the laboratory, also, this test requires to determine the endurance properties of the stem by using a materials testing machine to apply a sinusoidally varying force.