What causes corns and callouses?

Callouses and corns are areas where the skin has thickened in response usually to repetitive mechanical trauma. That may be severe trauma from a heel striking the ground at a repetitive angle, or soft gentle rubbing of the soft upper of a slipper against the top of a contracted toe, or inappropriate shoe design.

Why can’t a corn just be surgically removed and why do they come back?

Corns can be surgically removed but first the underlying mechanical cause needs to addressed otherwise the potential exists for a more complicated and painful lesion compounded by the surgical wound. If the cause is properly identified and treated the surgery may not be necessary.

Can I use medicated corn cures/ointments/pads?

While these can give short term relief for individuals with normal circulation and sensation. For those individuals with systemic illnesses like diabetes for example, these  self treatments can lead to tissue breakdown, ulceration and infection. As a general rule we would advise against their use.