The feasibility of using obturator internus muscle autotransplantation in order to construct an anal dilator mechanism for the treatment of obstructive constipation was studied anatomically, physiologically and pathologically. Electromyographic studies of 15 obturator internus muscles in 10 healthy adult male volunteers and 3 other muscles in patients with documented spastic anal sphincters demonstrated the ability of the obturator internus muscles to contract during straining at stools. The proposed surgical approach was studied in 9 cadavers (5 stillbirths and 4 adults), followed by formal anatomical dissection of the obturator internus muscle and tendon, pudendal nerve and vessels, inferior rectal nerve and nerve to the obturator internus. Anatomical studies proved the feasibility, ease, rapidity and safety of the technique with or without division of the obturator internus tendon with no incidence of injury to the surrounding nerves, vessels or muscles using a purely perineal approach.