Neuroma, injury or illness?

When someone have Morton's neuroma does it has injury or illness? What kind of condition is neuroma and what causes it? My grandma has this condition and she is going to have surgery next week.

Morton's neuroma is a benign inflammation of the nerves. It can affect any of the toes in the foot, but most often affects the nerves that run between the third and fourth or second and third toes. An inflammation is caused by a buildup of fibrous tissue on the outer coating of nerves running to the toes. This fibrous buildup is a reaction to the irritation resulting from nearby bones and ligaments rubbing against the nerves, for example: wearing shoes that are too tight repetitive trauma to the foot, an injury such as a sprain or fracture.