The Effects of Knee Motion and External Loading on the Length of the Anterior Cruciate Ligament (ACL): A Kinematic Study

Abstract

A six-degrees-of-freedom mechanical linkage device was designed and used to study the unconstrained motion of ten intact human cadaver knees. The knees were subjected to externally applied varus and valgus (V-V) moments up to 14 N-m as well as anterior and posterior (A-P) loads up to 100 N. Tests were done at four knee flexion angles; 0, 30, 45, and 90 deg. Significant coupled axial tibial rotation was found, up to 21.0 deg for V-V loading (at 90 deg of flexion) and 14.2 deg for A-P loading (at 45 deg of flexion). Subsequently, the knees were dissected and the locations of the insertion sites to the femur and tibia for the anteromedial (AM), posterolateral (PL), and intermediate (IM) portions of the ACL were identified. The distances between the insertion sites for all external loading conditions were calculated. In the case when the external load was zero, the AM portion of the ACL lengthened with knee flexion, while the PL portion shortened and the intermediate (IM) portion did not change in length. With the application of 14 N-m valgus moment, the PL and IM portions of the ACL lengthened significantly more than the AM portion (p less than 0.001). With the application of 100 N anterior load, the AM portion lengthened slightly less than the PL portion, which lengthened slightly less than the IM portion (p less than 0.005). In general, the amount of lengthening of the three portions of the ACL during valgus and anterior loading was observed to increase with knee flexion angle (p less than 0.001).

The Biomechanics of the Anterior Cruciate Ligament and Its Reconstruction

“…The effects of ACL transection on these findings were again dependent on constraint: in the constrained state the valgus range increased by 10%, but by 186% when unconstrained, and both valgus and varus were coupled with anterior translation. These results are corroborated by those of Hollis et al (1991), who found coupled internal and external rotation with applied valgus and varus torques, respectively.…”

“…When the knees were constrained to move only in anterior translation the measured translation was substantially less. In other cadaveric studies, application of a 100N anterior force produced coupled internal rotation (Hollis et al, 1991), and simulated 200N quadriceps contraction caused anterior tibial translation coupled with internal rotation (Li et al, 1999). Internal rotation due to anterior force is not a universal finding, with Lo et al (2008) showing a 50N anterior force (with a 100N joint compressive force) did not elicit a significant increase in rotation.…”

“…The findings presented here do not relate to the entire ligament, as many authors have found the behaviour to differ between the anteromedial and posterolateral bands. Several studies show reciprocal behaviour of the two bands, in that flexion causes the anteromedial band to lengthen and the posterolateral band to slacken, at least up to 120° (Amis & Dawkins, 1991;Bach et al, 1997;Hollis et al, 1991;Takai et al, 1993;Wang et al, www.intechopen.com 1973). But this picture of simple reciprocity may be an over-simplification.…”

Tibio-femoral joint constraints for bone pose estimation during movement using multi-body optimization

“…Several authors have focused on ligament kinematic behaviour with the aim to support ligament injury treatment: ACL and PCL elongation was investigated ex vivo [10,11] and in vivo [12][13][14]. Fewer studies have dealt with the MCL and LCL [15].…”

A method for measuring joint kinematics designed for accurate registration of kinematic data to models constructed from CT data

“…Mechanical linkage systems incorporate six degrees-of-freedom (6 joints) and use potentiometers or optical encoders to measure position of linkage joints and determine the end-to-end position and orientation (Chao, et al, 1980;Gardner, et al, 1996;Hollis, et al, 1991;Kinzel, et al, 1972;McClure, et al, 1998;Townsend, et al, 1977). 3 Mechanical linkages can achieve sub-millimeter accuracy, but the measurement space (linkage reach) tends to be limited to about 50 cm.…”