ePoster #307 - ISHA Annual Scientific Meeting 2016

Biomechanical Function of the Ligamentum Teres in Hip Rotational Range of Motion and Femoral Head Position

Jason Grieshober, MD, Manhattan Beach, CA UNITED STATES
Ronald S. Paik, MD, Chicago, IL UNITED STATES
Michael Banffy, MD, Los Angeles, CA UNITED STATES
Michelle H. Mcgarry, MS, Long Beach, CA UNITED STATES
Masaki Akeda, MD, Long Beach, CA UNITED STATES
Thay Q. Lee, PhD, Long Beach, CA UNITED STATES

Kerlan-Jobe Orthopaedic Clinic, Los Angeles, CA, UNITED STATES

FDA Status Not Applicable

Summary: This biomechanical study demonstrates that in addition to providing rotational stability, the ligamentum teres may function to limit medialization of the femoral head.

Background: The ligamentum teres (LT) is believed to be an important secondary stabilizer of the hip. The purpose of this study was to further elucidate the stabilizing role of the LT. Methods: Six cadaveric hemi-pelvises were mounted in a custom testing system. Maximum internal and external rotation were measured with 3Nm of torque at 0°, 30°, 60°, and 90° of flexion as well as 20° of abduction with neutral flexion. Position of the femoral head geometric center was determined at each of these positions. Maximum extension and abduction with 10Nm of torque were also measured. Testing was performed after exposure through the quadrilateral plate, and repeated after transection of the LT. Results: Total rotational motion was increased after LT transection, with the greatest increase at 90° of flexion (5.4°). In neutral rotation, the femoral head position shifted medially (0.9mm) at 0° flexion/ER, inferiorly (0.8mm) at 60° flexion/ER, posteriorly (1.0mm) and medially (1.8mm) at 90° flexion/ER. There was also a medial (1.4mm) and inferior (1.2mm) shift at 20° abduction/IR. Conclusion: The LT limited hip femoral rotation, particularly in hip flexion, but did not limit hip extension or abduction. The LT prevented medialization of the femoral head during hip motion. Increased medialization in LT deficient hips may result in elevated articular contact pressures. Clinical Relevance: The significance of the LT in limiting medialization of the femoral head in uncertain, but should be considered given the association of LT tears with hip joint chondrosis.