The same thing happens with bones – let’s say you want to adjust the bones and stop the plate at a certain point. The bone is attached with muscles around it and receives pressure from the skin, so it is common for the screws to come off and the small plates with screws to bend. This is like designing the hinge for a door, and for patients I saw that the burden is completely difference if the screw is 2mm in diameter, or 4mm in diameter. If you strike a screw with a large diameter, it can cause problems later with the wound.
So you apply engineering principles to restore and fix the position of the bones in surgery. Changes to the human body should be planned more precisely than houses, so simulating the procedure makes it more efficient for the patient.
There is a disease in my special field called funnel breast, where the ribs are deformed. You can create a 3D model from CT images of the patient, and then 3D print the model so you can see the bone and cartilage separately. The model is useful to see how the parts fit together, similar to what a carpenter is doing with say, a CAD design in architecture.