Hammertoe results from shoes that don’t fit properly or a muscle imbalance, usually in combination with one or more other factors. Muscles work in pairs to straighten and bend the toes. If the toe is bent and held in one position long enough, the muscles tighten and cannot stretch out.
Shoes that narrow toward the toe may make your forefoot look smaller. But they also push the smaller toes into a flexed (bent) position. The toes rub against the shoe, leading to the formation of corns and calluses, which further aggravate the condition. A higher heel forces the foot down and squishes the toes against the shoe, increasing the pressure and the bend in the toe. Eventually, the toe muscles become unable to straighten the toe, even when there is no confining shoe.