I woud think that the person has diabetes, people with diabetes have to take extra care of their feet due to the effects of their illness and circulation issues. Often times someone with diabetes cannot feel their feet very well so if they stub their toe or have an ingrowing toe nail, they cannot feel that. So it can actually be easy for someone to have to have an amputation if their diabetes is not controlled very well.

Other than that there are many people who hate going to the doctor and mental health issues (self neglect is part of many psychological issues) that would stop someone seeking medical attention.