Anatomy of the labrocapsular complex of the hip joint.

The acetabular labrum appears as a bundle of distinctly circular lined up collagenous fibers. It surrounds the limbus tangentially and is separated from the cartilagenous covered facies lunata through a thin gap (fissure) except of a small zone in the craniocaudal part. The labrum is strongly fixed with the transverse acetabular ligament. A vascular anastomotic ring surrounds the capsular attachement. It derives its blood supply especially from the superior gluteal vessels, the obturator artery and one ascending branch of the medial femoral circumflex artery. The innervation of the acetabular labrum is coming from a branch of the nerve to the quadratus femoris muscle and from the obturator nerve. There are all types of mechanoreceptors in the labrum. The acetabular labrum is able to exert a high tensional force on the rim of the acetabulum. This plays a very important role in view of the physiological, load depending incongruity of the articulating parts of the hip-joint.