The symphysis pubis. Anatomic and pathologic considerations.

The symphysis pubis is a nonsynovial amphiarthrodial joint that is situated at the confluence of the two pubic bones. A thick intrapubic fibrocartilaginous disc is sandwiched between thin layers of hyaline cartilage. The inferior pubic ligament provides most of the joint's stability. Anatomic sections demonstrate a symphysis by the end of the second month of gestation. Thick cartilaginous end-plates are present at birth but become thin by the time of skeletal maturity. Congenital diseases resulting in failure of symphysis formation include exstrophy of the bladder and cleidocranial dysostosis. Both pyogenic and tuberculous infectious diseases involve the symphysis. Metabolic disease, such as renal osteodystrophy, produces widening, while ochronosis results in calcific deposits in the symphysis. Inflammatory disease, such as ankylosing spondylitis, results in bony fusion of the symphysis. Osteitis pubis, the most common inflammatory disease, 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. As is the case with most joints, the symphysis serves as a barrier to tumor invasion. The patterns of trauma include diastasis, straddle fracture, intraarticular fracture and overlapping dislocation, and combinations of injuries.