Located at the center front of the pubic bone, the pubic symphysis is a cartilaginous joint that holds together the left and right halves of the front portion of the pelvis. On either side of this joint are the left and right superior pubic ramus, the inferior pubic ramus and the obturator foramen. The former two are portions of the pubic bone, and the latter is the opening in the front of the pelvis through which various nerves and ligaments pass to serve organs located within the pelvis, such as the bladder. Some ligaments that attach to the pubic symphysis help support the reproductive organs — for example, the ligament that supports the penis attaches to this area of the pelvis.
Though the pubic symphysis does not allow the wide range of movement of most joints in the body, its cartilaginous nature does allow the pubic bones to shift during walking and other common movement and allows the pelvic girdle to expand slightly during childbirth. During pregnancy, a specialized hormone called relaxen softens the cartilage of the pubic symphysis, allowing it to move a few millimeters more so that the infant may pass more easily through the pelvic girdle. Before the caesarean section was made possible by the discovery of antibiotics and more advanced surgical techniques, the pubic symphysis was sometimes separated surgically to allow for birth of a baby whose head was too large to pass through the mother's pelvis. This method occasionally still is used in emergencies when a modern operating facility is not available to perform a caesarean section and the lives of the mother or child are endangered by a mismatch between the size of the mother's pelvis and the size of the infant.
Many woman experience pubic bone pain through the latter part of pregnancy and sometimes for a short time after delivery because of the action of hormones on the pubic symphysis through pregnancy and childbirth. This pain is most noticeable while walking, while moving into a standing position or while getting dressed. Treatment often involves stabilizing the pelvis with a special binder, applying moist heat and reducing activities that cause discomfort. Severe pubic bone pain is known as pubic symphysis diastasis and usually occurs because of a misalignment or malfunction of this joint. If the pubic symphysis has actually separated completely or torn, special treatment is necessary, and it usually involves surgical repair.