The iliofemoral ligament (Y-ligament; ligament of Bigelow) is a band of great strength which lies in front of the joint; it is intimately connected with the capsule, and serves to strengthen it in this situation.
It is attached, above, to the lower part of the anterior inferior iliac spine; below, it divides into two bands, one of which passes downward and is fixed to the lower part of the intertrochanteric line; the other is directed downward and lateralward and is attached to the upper part of the same line. Between the two bands is a thinner part of the capsule. In some cases there is no division, and the ligament spreads out into a flat triangular band which is attached to the whole length of the intertrochanteric line.
This ligament is frequently called the Y-shaped ligament of Bigelow; and its upper band is sometimes named the iliotrochanteric ligament.