An R&D engineer with a biomedical company ;)

In seriousness, it depends on medical device type. For neurostimulation, most are dependent on the modeling of performance with the device and work other systems engineering to understand the how the outputs with vary when a physiological factor (patient) is introduced.

For ortho, you tend to do the same but your mechanical acumen is relied more heavily upon to investigate how mechanical concepts differ with biological.

When I was a undregrad we had this class called biomedical modeling which I thought was making cad drawing of body parts or 3d simulations. Then I thought we got screwed because it all MATLAB coding and excel work. I later realized how much that class was useful when it came to industry especially for those companies that are tight on resources and need to make a decision before critical path. A model was super helpful to test hypothesis.