Iliofemoral Ligament Superior Band: Anatomy, Attachments, Relations, Function, Clinical Significance, MRI & CT Imaging

Topic

Iliofemoral Ligament superior band (transverse band, lateral band)

The iliofemoral ligament, also called the Y-ligament of Bigelow, is the strongest ligament of the hip joint and has two parts: a superior (transverse, lateral) band and an inferior (vertical, medial) band. The superior band is the thicker, stronger component and plays a dominant role in preventing hyperextension and stabilizing the hip.

This band forms part of the anterior capsule of the hip joint, connecting the pelvis to the femur, and is critical for upright posture and bipedal locomotion.

Synonyms

Superior band of iliofemoral ligament
Transverse band of iliofemoral ligament
Lateral band of Y-ligament of Bigelow

Attachments

Proximal attachment (origin): Arises from the anterior inferior iliac spine (AIIS) of the pelvis
Distal attachment (insertion): Attaches to the intertrochanteric line of the femur, primarily its superior portion

Relations

Anteriorly: Iliopsoas tendon and femoral vessels
Posteriorly: Hip joint capsule and femoral head/neck
Superiorly: Gluteus minimus and hip capsule
Inferiorly: Inferior band of iliofemoral ligament, pubofemoral ligament

Nerve Supply

Supplied indirectly by articular branches of the femoral nerve and obturator nerve that innervate the hip joint capsule

Arterial Supply

Medial circumflex femoral artery
Lateral circumflex femoral artery
Obturator artery

Venous Drainage

Corresponding veins drain into the femoral vein and profunda femoris vein

Function

Resists hyperextension of the hip joint
Provides strong anterior reinforcement of the hip capsule
Aids in maintaining upright posture without muscular effort
Stabilizes the pelvis during standing, walking, and running

Clinical Significance

Injury or laxity may lead to anterior hip instability
Can be strained or torn in hip dislocations, trauma, or sports injuries
Serves as a landmark during hip arthroscopy and replacement surgery
Thickening and degeneration may be seen in chronic hip pathology

MRI Appearance

T1-weighted images:

Appears as a thin, low-signal intensity band connecting AIIS to intertrochanteric line
Surrounded by bright fat, which outlines the ligament

T2-weighted images:

Normal ligament shows dark (low-signal) appearance
Injury or sprain may show focal bright hyperintensity within or around ligament

STIR (Short Tau Inversion Recovery):

Normal ligament remains dark
Sprain, tear, or inflammation appears bright hyperintense
Pericapsular edema also seen as bright signal

T1 Fat-Sat Post-Contrast:

Normal ligament: minimal to no enhancement
Pathology: focal or diffuse enhancement in cases of inflammation, tear, or post-traumatic changes

CT Appearance

Non-Contrast CT:

Ligament not directly visible; identified as a thin soft tissue density thickening of anterior hip capsule
May be indirectly seen by contour of capsule
Calcification (rare) may appear as focal high-density area

Post-Contrast CT: