Interventions are medically necessary when they are vital in achieving the goal of medicine. However, with varying perspectives comes varying views on what interventions are (un)necessary and, thus, what potential treatment options are available for those suffering from the myriad of conditions, pathologies and disorders afflicting humanity. Medical necessity's teleological nature is perhaps best illustrated in cases where there is debate over using contentious medical interventions as a last resort. For example, whether it is appropriate for those suffering from body (...) integrity dysphoria to receive healthy limb amputations. This paper explores how one's perception of medicine's goal underpins whether interventions are necessary or unnecessary, using the controversial topic of therapeutic amputation as an example. By contrasting ‘classical’ amputations with their more contentious counterparts, it highlights how the idea of medical necessity influences and restrains clinical decision-making. The paper starts by giving an account of body integrity dysphoria, focusing on the debate concerning elective amputation's justifiability. It then introduces Georges Canguilhem's vitalist theory of health, paying particular attention to his emphasis on adaptability. Then, this paper uses his theory as a lens through which to evaluate the appropriateness of therapeutic amputation as a medically necessary procedure. Ultimately, the paper highlights how the label of medical necessity is withheld from potential therapeutic interventions because they fail to conform to pre-established ideas of medicine's purpose and that by doing so, potential harm befalls those who are left with no effective treatments and must look for solutions in the non-clinical world. (shrink)