Hammer toe is caused by tight shoes that force the toe into a flexed position, shortening the muscles and tendons. It most commonly affects the second toe, causing it to rotate downward into a claw-like position. Mild cases in children can be treated with foot manipulation and splinting, while wearing properly fitting shoes can help prevent worsening. For more severe cases, podiatrists may recommend straightening devices, exercises, or surgery to straighten the joint.