What are some reasons a person would have to get a limb amputated?

Limb amputate. 1. Safe life sometime, such as cancer, severe infection, severe trauma. 2. Improve function, control pain. It is not unusual the artificial limb can increase function than a dysfunction, painful limb.
Many possibilities. Some indications for performing an amputation may include: cancer of the affected part, infection, gangrene, and sever structural deformities.