Determination of thein situ forces and force distribution within the human anterior cruciate ligament

Abstract

The in situ forces and their distribution within the human anterior cruciate ligament (ACL) can clarify this ligament's role in the knee and help to resolve controversies regarding surgical treatment of ACL deficiency. We used a universal force-moment sensor (UFS) to determine the magnitude, direction, and point of application of the in situ forces in the ACL in intact human cadaveric knees. Unlike previous studies, this approach does not require surgical intervention, the attachment of mechanical devices to or near the ACL, or a priori assumptions about the direction of in situ force. Anterior tibial loads were applied to intact knees, which were limited to 1 degree of freedom at 30 degrees flexion. The in situ forces developed in the ACL were lower than the applied force for loads under 80 N, but larger for applied loads of more than 80 N. The direction of the force vector corresponded to that of the anteromedial (AM) portion of the ACL insertion on the tibial plateau. The point of force application was located in the posterior section of the anteromedial portion of the tibial insertion site. The anterior and posterior aspects of the anteromedial portion of the ACL supported 25% and 70% of the in situ force, respectively, with the remainder carried by the posterolateral portion. We believe that the data obtained with this new UFS methodology improves our understanding of the role of the ACL in knee function, and that this methodology can be easily extended to study the function of other ligaments.

Suture augmentation following ACL injury to restore the function of the ACL, MCL, and medial meniscus in the goat stifle joint

“…The robotic/universal force-moment sensor (UFS) testing system has been utilized by our research center and others for almost two decades to study joint kinematics and the in-situ forces of soft tissues in and around the joint (Abramowitch et al, 2003;Fujie et al, 1995;Livesay et al, 1995;Papageorgiou et al, 2001aPapageorgiou et al, , 2001bRudy et al, 1996). This system can accurately record the 6-DOF motion of the joint via its robotic manipulator (Puma Model 762, Unimate, Inc., Pittsburgh, PA).…”

Distribution of in situ forces in the anterior cruciate ligament in response to rotatory loads

“…The system can also be operated in force-control mode. With force-position feedback achieved between the UFS and the robotic manipulator, a desired force target could be achieved while the resulting changes in knee kinematics can be recorded [10, 21,28]. The UFS can measure 3 forces and 3 moments along a Cartesian axis system and has a repeatability of 0.2 N for forces and 0.01 N m for moments [29].…”

The current anatomical description of the inferior glenohumeral ligament does not correlate with its functional role in positions of external rotation

“…Custom fixtures were previously developed such that the scapula and humerus were rigidly fixed to the end effector and base of the robotic/universal force-moment sensor testing, respectively. [21][22][23][24][25][26][27][28][29] The joint was oriented at a minimal amount of glenohumeral abduction ($08), 08 of horizontal abduction, and 08 of external rotation.…”