Journal of Orthopaedic Research

Shinro Takai M.D., Savio L-Y. Woo Ph.D., Glen A. Livesay M.S., Douglas J. Adams M.S. and F. H. Fu, M.D.


A non-contact, kinematic method was used to determine the lengths and in-situ loads borne by portions of the human anterior cruciate ligament (ACL) by combining kinematic data from the intact knee and load vs. length curves of the ACL. Young human cadaveric knee specimens were tested in passive flexion and extension as well as under 100 N of anterior tibial drawer at 0*, 30*, 45*, and 90* of flexion. The results showed that the in-situ load on the whole ACL (up to 120 N) can exceed the applied anterior tibial drawer force. The load distribution within the ligament changes with knee flexion. The anterior and posterior portions share the anterior drawer force equally toward full extension. However, at flexion angles greater than 45*, the anterior portion supports 90-95% of the load. This information is important in determining the function of both the entire ACL and its' sub-portions in response to external loading of the intact knee. In particular, the preferential loading found for one of the portions of the ACL demonstrates that successful surgical reconstruction of this ligament may not be achieved by simply reproducing its' gross anatomy; consideration of the role of the ligament in the overall kinematics of the knee is necessary.