Use of Robotic Manipulators to Study Diarthrodial Joint Function

Abstract

Diarthrodial joint function is mediated by a complex interaction between bones, ligaments, capsules, articular cartilage, and muscles. To gain a better understanding of injury mechanisms and to improve surgical procedures, an improved understanding of the structure and function of diarthrodial joints needs to be obtained. Thus, robotic testing systems have been developed to measure the resulting kinematics of diarthrodial joints as well as the in situ forces in ligaments and their replacement grafts in response to external loading conditions. These six degrees-of-freedom (DOF) testing systems can be controlled in either position or force modes to simulate physiological loading conditions or clinical exams. Recent advances allow kinematic, in situ force, and strain data to be measured continuously throughout the range of joint motion using velocity-impedance control, and in vivo kinematic data to be reproduced on cadaveric specimens to determine in situ forces during physiologic motions. The principle of superposition can also be used to determine the in situ forces carried by capsular tissue in the longitudinal direction after separation from the rest of the capsule as well as the interaction forces with the surrounding tissue. Finally, robotic testing systems can be used to simulate soft tissue injury mechanisms, and computational models can be validated using the kinematic and force data to help predict in vivo stresses and strains present in these tissues. The goal of these analyses is to help improve surgical repair procedures and postoperative rehabilitation protocols. In the future, more information is needed regarding the complex in vivo loads applied to diarthrodial joints during clinical exams and activities of daily living to serve as input to the robotic testing systems. Improving the capability to accurately reproduce in vivo kinematics with robotic testing systems should also be examined.

In situ force in the anterior cruciate ligament, the lateral collateral ligament, and the anterolateral capsule complex during a simulated pivot shift test

“…The position and orientation repeatability of the robotic manipulator is less than ±0.015 mm and ±0.01°. The unique orthogonal design of the custom robotic manipulator also provides high clamp‐to‐clamp stiffness (110 ± 30 Nm/degree for rotations and 450 ± 180 N/mm) making it appropriate for mechanical testing of the knee joint . Also as presented previously, the test–retest repeatability of the robotic testing systems was determined to be ±0.21 mm and ±2.45° and repeatability of recording the in situ forces in the robotic testing system is ±2.25 N.…”

A Robotic Glenohumeral Simulator for Investigating Prosthetic Implant Subluxation

“…[31], but in addition had the ability to generate actuated rotations over two axis, which were not produced with some other robotic simulators [10,21,22]. Moreover, unlike existing simulators [24,32] where the force was limited (e.g., to 200 N), it was possible to produce enough load on the prosthesis (e.g., up to 2 kN) to simulate situations found in diverse activities of daily living. Actually, the force range of the proposed simulator fit the same range as observed in real patients [33] allowing to simulate better activities of daily living.…”

“…Fujie et al [31] proposed to use actuators orthogonally placed around a diarthrodial joint, in order to have simpler control schemes and an improved accuracy during their simulations. Combining their simulator with cadaveric joints, they were able to evaluate the force exerted by most of the ligaments of the glenohumeral capsule during different levels of arm abduction [32]. However, this simulator was demonstrated to work only with low loads (200 N), whereas vivo measurements [33] displayed larger loads, raising beyond 500 N in most cases.…”

Sex-Specific Function and Morphology of the Anterior Cruciate Ligament During Skeletal Growth in a Porcine Model

“…The force contributions of the ACL, AM bundle, and PL bundle during anterior drawer were calculated using the principle of superposition. 36; 37 The anterior force carried by the ACL was calculated as a percentage of the total anterior force in the knee joint under maximum anterior translation. The anterior forces carried by the AM and PL bundles were calculated as a percentage of the anterior force in the ACL under maximum anterior translation.…”