Ligamentum capitis femoris
The ligamentum teres, also known as the ligamentum capitis femoris or round ligament of the hip, is an intra-articular ligament within the medial hip joint.
The ligament passes from the transverse ligament and acetabular notch of the acetabulum to the femoral head where it inserts into a shallow depression called the fovea capitis. The ligament is lined by synovium. It ranges from a well-formed structure in some patients to absent in others (case 2).
In the infant it has a significant role so far as it transmits a nutrient artery to the femoral head epiphysis. In the adult, its role is poorly understood, and there are several hypothesized functions which include :
- maintains the upright position as it is tightest when erect and weight-bearing
- aids fine coordination of the hip joint
- additional hip stabilizer in patients with generalized ligamentous laxity, hip dysplasia and in patients with anteroinferior acetabular deficiency
- maintain lubrication in the joint by aiding the distribution of synovial fluid
- congenital absence of the ligamentum teres
- ligament rupture or tear
- avulsion fracture of the fovea capitis (case 3)