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

Topic

Iliofemoral ligament

The iliofemoral ligament, also known as the Y ligament of Bigelow, is the strongest ligament of the hip joint. It is a thick, fibrous band located on the anterior aspect of the hip joint, reinforcing the capsule and preventing hyperextension. Its shape resembles an inverted “Y,” and it plays a critical role in maintaining upright posture and limiting excessive motion at the hip.

It is of high clinical importance due to its role in hip stability, frequent involvement in injuries, and relevance in surgical and radiological evaluation of the hip joint.

Synonyms

Y ligament of Bigelow
Anterior ligament of the hip
Iliofemoral capsular ligament

Attachments and Course

Proximal Attachment (Origin):
- Arises from the anterior inferior iliac spine (AIIS)
- Extends partially from the adjacent acetabular rim
Course:
- Fibers pass inferiorly and laterally across the front of the hip joint
- The ligament fans out into a Y-shaped structure
- Lies anterior to the hip capsule, blending with it
Distal Attachment (Insertion):
- Attaches to the intertrochanteric line of the femur
- Divides into two limbs: a lateral band and a medial band, together forming the “Y” shape

Relations

Anteriorly: Iliopsoas tendon and overlying femoral vessels
Posteriorly: Hip joint capsule and femoral head
Laterally: Greater trochanter of the femur
Medially: Pubofemoral ligament

Nerve Supply

Articular branches from the femoral nerve
Secondary contributions from the obturator nerve

Arterial Supply

Branches of the medial circumflex femoral artery
Ascending branches of the lateral circumflex femoral artery
Small contributions from the obturator artery

Venous Drainage

Corresponding venous channels drain into the medial and lateral circumflex femoral veins, which join the profunda femoris vein

Function

Prevents hyperextension of the hip joint during standing and walking
Limits excessive external rotation and abduction
Provides static stability of the hip joint
Reduces muscular effort required to maintain upright posture

Clinical Significance

Injury or laxity may lead to hip instability and predispose to dislocation
Important landmark in anterior surgical approaches to the hip
Contributes to stability in conditions such as hip osteoarthritis or femoroacetabular impingement
Plays a role in rehabilitation and orthopedic assessment of hip joint stability

MRI Appearance

T1-weighted images:

Ligament shows low signal intensity as a fibrous band
Fatty surroundings appear bright, improving contrast

T2-weighted images:

Normal ligament remains low signal
Partial tear, sprain, or edema appears bright

STIR (Short Tau Inversion Recovery):

Suppresses fat, ligament appears dark
Edema, inflammation, or tear appear bright

Proton Density Fat-Sat (PD FS):

Normal ligament remains low signal
High-signal intensity indicates sprain or tear

T1 Fat-Sat Post-Contrast:

Ligament itself does not enhance
Surrounding inflamed tissues or synovium may show enhancement

CT Appearance

Non-Contrast CT:

Appears as a dense fibrous band, often indistinct but identifiable adjacent to the hip capsule
Calcification or ossification may be seen in chronic degeneration

Post-Contrast CT: