Applying Simulated In Vivo Motions to Measure Human Knee and ACL Kinetics

Abstract

Patients frequently experience anterior cruciate ligament (ACL) injuries but current ACL reconstruction strategies do not restore the native biomechanics of the knee, which can contribute to the early onset of osteoarthritis in the long term. To design more effective treatments, investigators must first understand normal in vivo knee function for multiple activities of daily living (ADLs). While the 3D kinematics of the human knee have been measured for various ADLs, the 3D kinetics cannot be directly measured in vivo. Alternatively, the 3D kinetics of the knee and its structures can be measured in an animal model by simulating and applying subject-specific in vivo joint motions to a joint using robotics. However, a suitable biomechanical surrogate should first be established. This study was designed to apply a simulated human in vivo motion to human knees to measure the kinetics of the human knee and ACL. In pursuit of establishing a viable biomechanical surrogate, a simulated in vivo ovine motion was also applied to human knees to compare the loads produced by the human and ovine motions. The motions from the two species produced similar kinetics in the human knee and ACL. The only significant difference was the intact knee compression force produced by the two input motions.

Anterior cruciate ligament biomechanics during robotic and mechanical simulations of physiologic and clinical motion tasks: A systematic review and meta-analysis

“…[20] Further adaptations were made to apply the mean ovine motion, as well as in vivo recorded human gait kinematics, onto cadaveric specimens. [34] Superposition again allowed investigators to quantify the biomechanical contributions of the ACL during kinematic-derived simulations.…”

Knee Abduction Affects Greater Magnitude of Change in ACL and MCL Strains Than Matched Internal Tibial Rotation In Vitro

“…An explicit account of specimen preparation procedures was previously documented [6,23]. Specimen criteria were defined as no history of knee trauma, knee surgery, bone cancer, or ankle or shin implants.…”

“…Most models that have quantified mechanical contributions to ligament load and strain are constrained via a combination of force, torsional, and anatomic restrictions [5,15,19,20,28,32,35,40,41,43,46,49,[51][52][53][56][57][58]. Only limited literature is available pertaining to models of dynamic tasks that are precision constrained relative to in vivo kinematics [6][7][8][9]23]. Accordingly, there is a gap in knowledge regarding the quantification of how a precise, physiologically relevant kinematic perturbation influences change on these in vitro models.…”

“…Much of this work has evaluated and improved the efficaciousness of surgical methods and graft material selections used in ACL reconstructions with respect to native ACL biomechanics [12,15,19,20,28,35,43,49,51,[56][57][58]. These simulations have also gathered data on the mechanical contributions of the intact ACL in response to Lachman's and pivot shift tests [15,19,20,28,35,43,49,51,[56][57][58], gait cycles [23,39], and landing impact forces [32,40,41,46,52,53]. The accrued data have advanced the knowledge of ACL function and provided a baseline of comparison by which to evaluate the effectiveness of ACL injury treatments.…”

“…Within the past 20 years, robotic methods of joint articulation have allowed investigators to examine the underlying mechanical behaviors through more physiologic simulations of activities of daily living on cadaveric specimens [12,23,26,39]. These in vitro data would be unobtainable in vivo as a result of the invasive nature of biomechanical testing.…”