Joints and ligaments · Lower limb
Transverse acetabular ligament !
The transverse acetabular ligament bridges the gap at the bottom of the hip socket rim, completing the ring.
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What it is
A ligament that bridges the notch at the bottom of the hip socket rim.
What it does
Completes the ring formed by the socket and labrum. Surgeons use it as a landmark when placing the cup of a hip replacement.
Key facts
- Attaches
- Bridges acetabular notch, continuous with acetabular labrum
- Function
- Completes acetabular rim; vessels and nerves pass beneath it into the joint
Relations
- Above
- Attachment of the ligament of the femoral head and the pulvinar fat pad in the acetabular fossa
- Below
- Acetabular notch, with vessels and nerves passing under it into the joint
- Lateral
- Acetabular labrum, continuous with it at both ends of the notch
How to find it
In hip replacement it is found at the lower edge of the socket, bridging the acetabular notch, once the femoral head has been dislocated and the ligament of the head and the pulvinar fat cleared away. At arthroscopy it lies at the lower ends of the horseshoe-shaped lunate surface.
On imaging
On MR arthrography it is a low-signal band at the bottom of the acetabulum. The groove where it meets the labrum (labroligamentous sulcus) can mimic a labral tear.
Clinical notes
- In an arthritic hip, osteophytes or soft tissue may hide it; clearing them shows the true bottom of the socket for cup placement
- Releasing it can deepen access to the true acetabulum during open reduction of a dysplastic hip
Test yourself
Think of the answer, then tap the question to see it.
What does the transverse acetabular ligament bridge, and what passes beneath it?
The acetabular notch; vessels and nerves pass beneath it into the joint, including acetabular branches of the obturator and medial circumflex femoral arteries.
How is the transverse acetabular ligament used in hip replacement?
Aligning the cup rim with it helps reproduce the patient's own acetabular anteversion.
Which normal groove at the transverse acetabular ligament can mimic a labral tear on MR arthrography?
The labroligamentous sulcus, where the ligament meets the labrum.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- ligamentum transversum acetabuli TA2 1881
- Official Spanish (DeCS)
- Ligamento transverso del acetábulo
- English (TA2)
- Transverse acetabular ligament
Related
Sources: Terminologia Anatomica (TA2); Anatomy, Bony Pelvis and Lower Limb, Hip Joint.
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Representative model, for educational purposes only.
