Injury and reconstruction of the anterior cruciate ligament and knee osteoarthritis

Objective: The objective of this study was to study injury and reconstructi on of the anterior cruciate ligament (ACL) and their effects on knee osteoa rthritis. Design: This manuscript discusses the function of knee ligaments, including the basic mechanical properties, the structural properties of their respec tive bone-ligament-bone complexes, as well as their time- and history-depen dent viscoelastic characteristics. The in-situ forces in the ACL and its re placement grafts and knee kinematics before and after ACL reconstruction ar e also examined. Results: A robotic/universal force-moment sensor (UFS) testing system has b een developed which offers a unique method in determining the multiple-degr ee of freedom knee kinematics and in-situ forces in human cadaveric knees. Under a 110 N anterior tibial load we found at flexion angles of 15 degrees or lower, there was a significantly larger in-situ force in the PL bundle (approximately 75 N) of the ACL as compared to the AM bundle (approximately 35 N) (P < 0.05). We also found that a quadruple semitendinosus and gracil is tendon ACL graft may be better at fully restoring in-situ forces for the whole range of knee flexion when compared to a bone-patellar tendon-bone A CL graft. Conclusions: The robotic/UFS testing system allows us to determine knee kin ematics and the in-situ forces in cadaveric knees in a non-invasive, non-co ntact manner. Additionally, the ability to reproduce kinematics during test ing allows us to evaluate ACL and ACL graft function under external and sim ulated muscle loading conditions. Finally, we can also examine many of the variables of ACL reconstructions that affect knee kinematics and graft forc es including graft tensioning, graft type, graft placement and tibial posit ioning during graft fixation.