Introduction[edit | edit source]
The hip joint is composed of five ligaments, where four are extracapsular and one intracapsular. The extracapsular ligaments are the iliofemoral, the ischiofemoral, the pubofemoral and the annular ligament (or zona orbicularis), the intrcapsular one is the ligament of the head of the femur. The iliofemoral ligament is also called Y ligament for is triangular shape or ligament of Bigelow, the name of the American surgeon who, among other things, described this ligament in details and invented the Bigelow maneuver for hip dislocation. 
Anatomy[edit | edit source]
The iliofemoral ligament arises from the anterior inferior iliac spine (AIIS) and from the rim of the acetabulum, and it runs obliquely and attaches to the intertrochanteric line of the femur. It is composed of two bands, a medial band that is vertically oriented and runs almost parallel to the femoral shaft, and a lateral band that has fibers obliquely directed and runs parallel to the axis of the femoral neck. The medial band of the ligament attaches to the lower part of the intertrochanteric line and the lateral band attaches to the upper part of the same line. These two bands create the Y-shape. In some anatomical variations this division does not exist, and the ligament spreads out into a flat triangular band, that attaches to the whole length of the intertrochanteric line.  Even if it is an extracapsular ligament, it is anatomically connected with the capsule of the hip joint.
Function[edit | edit source]
The iliofemoral ligament is considered the strongest ligament of the body as it can support a traction up to 350 kg. It has a relevant role in the hip joint stability. Generally, the hip's ligaments provide a slack region in mid flexion, where the muscles can freely move the joint in internal rotation, external rotation, abduction or adduction. Instead, the ligaments are taut in full flexion, extension, abduction and adduction, where the ball and socket shape of the hip joint cannot provide mechanical stability. 
The iliofemoral ligament limits extension, external rotation in full flexion and external and internal rotation in full extension of the hip. Moreover, it seems that it can assist the maintenance of static erect posture, mostly when the musculuar activity of the hip stabilizers is minimal. In fact, a histologic study  shows that the direction of collagen fibres in the iliofemoral ligament are parallel to the macroscopic direction of the tissue, and it suggets that the ligament plays a role in restricting the extension of the hip. Moreover, the study founded tha the ligament contribute to the stability of the hip joint in the standing position because of the low density of the crimp distribution in the longitudinal plane.
Relevance in physiotherapy[edit | edit source]
As previously said this ligament is important for the stability of the hip joint both in dynamic conditions (rotations in extension and flexion of the hip) and static condition, supporting the weight of the body. Because of its versatility, this ligament can be injuried for example for a partial or full tear from a direct blow to the hip or for overuse. Data about the frequency in which these conditions occur are lacking in literature. The tests used to detect an injury of the iliofemoral ligament:
- Prone instability: patient in prone position, the examiner applies passive external rotation while applying an anteriorly directed force on the trochanter. Sign: hip joint pain or sense of anterior instability.
- HEER/Anterior apprehension: patient in supine at the end of the table with the affected leg hanging off and unaffected knee toward chest; passive hip extension and external rotation are applied. Sign: Hip joint pain or sense of anterior instability.
- AB-HEER: patient in side lying on unaffected hip; passive hip abduction to 30°, extension 10° and external rotation to end range while an anteriorly directed force applied to trochanter. Sign: Hip joint pain or sense of anterior instability.
References[edit | edit source]
- D’Ambrosi, R., Ursino, N., Messina, C., Della Rocca, F., and Hirschmann, M. T. The role of the iliofemoral ligament as a stabilizer of the hip joint. EFORT Open Reviews. 2021 vol. 6(7), pp. 545-555.
- Tsutsumi M, Nimura A, Akita K. New insight into the iliofemoral ligament based on the anatomical study of the hip joint capsule. Journal of Anatomy. 22 December 2019, Volume236, Issue5.
- Sato K, Uchiyama E, Katayose M, Fujimiya M. Microscopic analysis of the iliofemoral and ischiofemoral ligaments in the hip joint: collagen fiber direction and crimp distribution. Anat Sci Int. 2012 Mar;87(1):50-5. doi: 10.1007/s12565-011-0117-7. Epub 2011 Oct 18. PMID: 22006046.