Implementation of a five degree of freedom automated system to determine knee flexibility in vitro

Berns, G. S.; Hull, M. L.; Patterson, H. A.

Affiliations

¹Biomedical Engineering Graduate Group, University of California, Davis, CA 95616

²Department of Mechanical Engineering, University of California, Davis, CA 95616

³Department of Human Anatomy, University of California, Davis, CA 95616

Abstract

This article describes an automated system designed to study the complete flexibility functions of the knee in vitro. The system allows five degrees of freedom with flexion angle being fixed, though adjustable from 0 to 45 deg. Loads corresponding to each of the five motions can be applied independently and in any combination. The effect of weight bearing on knee flexibility can also be studied by including axial force as one of the five loads. The relative motions are measured with LVDT’s and RVDT’s, and the loads are measured with strain gage transducers. The system is digitally controlled with a closed feedback loop, allowing for any combination of programmed loads. A control algorithm on an IBM PC/AT monitors the loads on each axis and continuously adjusts stepping motors to correctly follow programmed loads. The machine coordinate system corresponds to clinically accepted definitions of motion yet retains sequence independence for rotations. Results are presented demonstrating the repeatability of using a functional definition of axis placement to align the leg within the machine. Results are also presented demonstrating the utility of the full flexibility functions of the knee, notably in the determination of significant load interactions between anterior/posterior force and internal/external torque, and varus/valgus torque and internal/external torque.

Links

DOI: 10.1115/1.2891202

PubMed: 2273865

WoS: A1990EL16300005

History

Received: 1989-04-10

Revised: 1990-05-25

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Cited By (10)

Year	Entry
1996	Hull ML, Berns GS, Varmat H, Patterson HA. Strain in the medial collateral ligament of the human knee under single and combined loads. J Biomech. February 1996;29(2):199-206.
2003	Haut Donahue TL, Hull ML, Rashid MM, Jacobs CR. How the stiffness of meniscal attachments and meniscal material properties affect tibio-femoral contact pressure computed using a validated finite element model of the human knee joint. J Biomech. January 2003;36(1):19-34.
1993	Fujie H, Mabuchi K, Woo SL-Y, Livesay GA, Arai S, Tsukamoto Y. The use of robotics technology to study human joint kinematics: a new methodology. J Biomech Eng. August 1993;114(3):211-217.
1995	Bach JM, Hull ML. A new load application system for in vitro study of ligamentous injuries to the human knee joint. J Biomech Eng. November 1995;117(4):373-382.
2002	Haut Donahue TL, Hull ML, Rashid MM, Jacobs CR. A finite element model of the human knee joint for the study of tibio-femoral contact. J Biomech Eng. June 2002;124(3):273-280.
1997	Debski RE. A Combined Experimental and Computational Approach to Examine the Function of the Capsuloligamentous Structures At the Glenohumeral Joint [PhD thesis]. University of Pittsburgh; 1997.
2008	Schimoler PJ. Design of a Control System for an Elbow Joint Motion Simulator [Master's thesis]. University of Pittsburgh; 2008.
2000	Haut Donahue TL. A Finite Element Model of the Human Knee Joint for the Study of Meniscal Replacements [PhD thesis]. Davis, University of California; 2000.
2023	Kalra M. An in-Vitro and Finite Element Investigation on the Efficacy of Unloader Knee Braces on Meniscus Strain and Tibiofemoral Pressure [PhD thesis]. University of Waterloo; 2023.
2001	Dunning CE. Development of a Motion-Controlled Testing Apparatus and Kinematic Techniques to Simulate and Describe Elbow Motion (development of Tools to Simulate and Describe Elbow Motion) [PhD thesis]. London, ON: University of Western Ontario; 2001.