Following up on last week’s article on the role of the hip labrum (if you missed that one, check it out here), we are talking about the the next layer of stabilizing structures of the hip – the capsuloligamentous complex. This big word simply means the ligaments and capsule that surround the hip.
The Capsuloligamentous Anatomy
Kalisvaart, M. M., & Safran, M. R. (2015). Microinstability of the hip—it does exist: etiology, diagnosis and treatment. Journal of hip preservation surgery, 2(2), 123-135.The hip joint is surrounded by 3 large ligaments – the iliofemoral ligament, the pubofemoral ligament and the ischiofemoral ligament, which all blend together to form the hip capsule. In addition to those 3, there are also the zona orbicularis and the ligamentum teres, which also play important roles in stabilizing the hip joint.
The iliofemoral ligament (also called the Y ligament) is the strongest ligament of the 3 (Nho et al., 2015). It sits anterior to the hip joint in an inverted Y shape, with a superior and inferior band. The iliofemoral ligament is maximally taught in extension (Nho et al., 2015), and limits hip ER and anterior translation of the femur (Johannsen et al., 2019). There is also some evidence that indicates it may have an attachment with the tendinous origin of the rectus femoris (Nho et al., 2015). The pubofemoral ligament lies just inferior to the iliofemoral ligament and covers the anteroinferior part of the hip joint. A portion of this ligament actually blends with the inferior band of the iliofemoral ligament at the distal attachment (Nho et al., 2015). There is also a portion if this ligament that runs perpendicular to the zona orbicularis. This ligament is maximally taught in hip abduction and limits hip abduction. The ischiofemoral ligament reinforces the joint capsule posteriorly and is thought to limit hip internal rotation. The zona orbicularis is a circumferential ligament that creates a sling around the the femoral neck. This ligament also reinforces the capsule posteriorly. Finally, the ligamentum teres sits inside the joint, stemming from the inside surface of the acetabulum and inserting onto the head of the femur. Originally thought to not play a role in stabilizing the hip, it is now suggested to contribute as an intrinsic hip stabilizer, providing stability against subluxation.
The Role of the Capsuloligamentous Complex
So that was a lot of big words and fancy terms, but why is that all important? There is evidence that suggests that we can stretch these ligaments to the point that we can increase movement in the hip joint, also known as microinstability. Johannsen et al. (2019) found that stretching the ilifemoral ligament created a significant increase in hip internal and external ROM after stretching and a significant increase in femoral head displacement after stretching. They suggest that repetitive microtraumatic activities that put strain on the iliofemoral ligament, such as twisting and pivoting in sports, may be a mechanism for atraumatic hip microinstability. This was also suggested by Myers et al. (2011) and Kalisvaart et al. (2015), who both also discussed that having abnormal femoral head translation can cause increased tension and breakdown of the labrum, as I previously mentioned in a previous article, and cause microtrauma to the capsule which can lead to capsular ligament stretching and possibly symptomatic hip microinstability.
Another interesting finding from a research article by Philippon et al. (2010) was that 26/28 NHL players who underwent arthroscopic FAI and labral repair surgery also had ligamentum teres lesions significant enough to be debrided. As previously mentioned, it is thought that the ligamentum teres functions to restrict hip joint subluxation and as I mentioned in a previous article, skating produces approximately 350N of abduction force which would cause a distraction force on the hip. If pathological structures such as the labrum and the ligaments such as the iliofemoral ligament aren’t doing a good job at stabilizing, this could be putting more strain on the ligamentum teres to prevent the femoral head from subluxing.
Part 3 of this series will talk about the hip rotator cuff muscles, which is an integral concept in increasing stability in the hip joint.
Like this post? Want to learn more about hip pathology and rehab? Check out my website www.be-elite.ca and on IG @alwaysbeelite.
References
Kalisvaart, M. M., & Safran, M. R. (2015). Microinstability of the hip—it does exist: etiology, diagnosis and treatment. Journal of hip preservation surgery, 2(2), 123-135.
Johannsen, A. M., Behn, A. W., Shibata, K., Ejnisman, L., Thio, T., & Safran, M. R. (2019). The Role of Anterior Capsular Laxity in Hip Microinstability: A Novel Biomechanical Model. The American journal of sports medicine, 47(5), 1151-1158.
Nho, S. J., Leunig, M., Larson, C. M., Bedi, A., & Kelly, B. T. (Eds.). (2015). Hip arthroscopy and hip joint preservation surgery. Springer New York.
Philippon, M. J., Weiss, D. R., Kuppersmith, D. A., Briggs, K. K., & Hay, C. J. (2010). Arthroscopic labral repair and treatment of femoroacetabular impingement in professional hockey players. The American journal of sports medicine, 38(1), 99-104.
Myers, C. A., Register, B. C., Lertwanich, P., Ejnisman, L., Pennington, W. W., Giphart, J. E., … & Philippon, M. J. (2011). Role of the acetabular labrum and the iliofemoral ligament in hip stability: an in vitro biplane fluoroscopy study. The American journal of sports medicine, 39(1_suppl), 85-91.