Iliofemoral ligament (Y-ligament, Ligament of Bigelow)

Structure

• Inverted “Y” shaped
• Proximal attachment: Lower part of Anterior inferior iliac spine (AIIS) and rim of acetabulum
• Distal attachment: Divides into 2 bands which attaches to inferomedial (vertically oriented fibers) and superolateral (obliquely oriented fibers) part of inter-trochanteric line
• More than 0.5 cm thick
• Rupture strength: 350 kg

It is one of the strongest ligaments in the body, the other being the interosseous sacro-iliac ligament.

Functions

1. Strengthens the anterior part of the articular capsule
2. Prevents hyperextension of joint when standing
   • In the erect posture, the center of gravity of the body falls slightly behind a line joining the centers of the two hip joints. As such, there is a natural tendency for the body to fall backwards on the hip joints. This is resisted by the iliofemoral ligaments.

Clinical correlates

1. Hip dislocation: In hip dislocation, the surgeon may use the iliofemoral ligament as a support to lever the head of the femur back into the acetabulum.
2. Hip dysplasia: Patients with hip dysplasia were found to have thinner iliofemoral ligaments

References:

1. Anatomy, descriptive and applied – Henry Gray
2. Cunningham’s manual of practical anatomy – 16th edition
3. Iliofemoral Ligament | Complete Anatomy