The Effect of Position and Path Repeatability on Biomechanical Testing of Diarthrodial Joints

Abstract

To improve surgical procedures and rehabilitation protocols for injuries to the anterior cruciate ligament (ACL), the function of the ACL and ACL graft during in vivo activities must be understood. Robotic manipulators with a payload less than 500 N (low-payload) have been used to study joint and ligament function during application of external loading conditions (Fujie, 1993; Fujie, 2000). Robotic manipulators with a payload capacity of at least 1500 N (high-payload) will be needed to simulate high joint contact forces that have been estimated to be between 2 to 5 times body weight (Morrison, 1970; Escamilla, 1998). However, there is a trade-off between payload capacity and position and path repeatability. The objective of this study was to determine the effect of position and path repeatability of two high-payload robotic manipulators, (KUKA™ KR210 and FANUC™ S900W) used to apply external loads to diarthrodial joints and determine the corresponding joint kinematics and forces in the soft tissue structures.