Pubic symphysis

Fibrocartilage is composed of small, chained bundles of thick, clearly defined, type I collagen fibers. This fibrous connective tissue bundles have cartilage cells between them; these cells to a certain extent resemble tendon cells. The collagenous fibers are usually placed in an orderly arrangement parallel to tension on the tissue. It has a low content of glycosaminoglycans (2% of dry weight). Glycosaminoglycans are long, unbranched polysaccharides (relatively complex carbohydrates) consisting of repeating disaccharide units. Fibrocartilage does not have a surrounding perichondrium. Perichondrium surrounds the cartilage of developing bone; it has a layer of dense, irregular connective tissue and functions in the growth and repair of cartilage.

Hyaline cartilage is the white, shiny gristle at the end of long bones. This cartilage has poor healing potential, and efforts to induce it to repair itself frequently end up with a similar, but poorer fibrocartilage.

In the newborn, the symphysis pubis is 9–10 mm in width, with thick cartilaginous end-plates. By mid-adolescence the adult size is achieved. During adulthood the end-plates decrease in width to a thinner layer. Degeneration of the symphysis pubis accompanies aging and postpartum. Women have a greater thickness of this pubic disc which allows more mobility of the pelvic bones, hence providing a greater diameter of pelvic cavity during childbirth.

The pubic symphysis widens slightly when the legs are stretched far apart. In sports where these movements are often performed, the risk of a pubic symphysis blockage is high, in which case, after completion of the movement, the bones at the symphysis do not realign correctly and can get jammed in a dislocated position. The resulting pain can be severe, especially when further strain is put upon the affected joint. In most cases, the joint can only be successfully reduced into its normal position by a trained medical professional.

Metabolic diseases, such as renal osteodystrophy, produce widening, while ochronosis results in calcific deposits in the symphysis. Inflammatory diseases, such as ankylosing spondylitis, result in bony fusion of the symphysis. Osteitis pubis, the most common inflammatory disease in this area, is treated with anti-inflammatory medication and rest. Degenerative joint disease of the symphysis, which can cause groin pain, results from instability or from abnormal pelvic mechanics.[3]

Symphysiolysis is separation or slipping of the symphysis. It has been estimated to occur in 0.2% of pregnancies.[4]

During pregnancy in the human, hormones such as relaxin remodel this ligamentous capsule allowing the pelvic bones to be more flexible for delivery. The gap of the symphysis pubis, normally is 4–5 mm but during pregnancy there will be an increase of at least 2–3 mm, therefore, it is considered that a total width of up to 9 mm between the two bones is normal for a pregnant woman. The symphysis pubis separates to some degree during childbirth. In some women this separation can become a diastasis of the symphysis pubis. The diastasis could be the result of a rapid birth,[5] or a forceps delivery,[6] or may be a prenatal condition.[7] A diastasis of the symphysis pubis is a cause of pelvic girdle pain (PGP). Overall, about 45% of all pregnant women and 25% of all women postpartum suffer from PGP.[8]

Symphysiotomy is a surgical procedure in which the cartilage of the pubic symphysis is divided to widen the pelvis allowing childbirth when there is a mechanical problem. It allows the safe delivery of the fetus where Caesarean section is not an option. Symphysiotomy is suggested for woman in isolated areas experiencing obstructed labor where other medical intervention is unavailable.[9]

This practice was carried out in Europe before the introduction of the Caesarean section. Historically, during obstructed labor, the skull of the fetus was also, at least occasionally, crushed in order to further facilitate the delivery.[10]

Pubic symphyses have importance in the field of forensic anthropology, as they can be used to estimate the age of adult skeletons. Throughout life, the surfaces are worn at a fairly predictable rate. By examining the wear of the pubic symphysis, it is possible to estimate the age of the person at death.[11]