Ali Erkan Engin

Two-dimensional dynamic modelling of human knee joint

A mathematical dynamic model of the two-dimensional representation of the knee joint is presented. The profiles of the joint surfaces are determined from X-ray films and they are represented by polynomials. The joint ligaments are modelled as nonlinear elastic springs of realistic stiffness properties. Nonlinear equations of motion coupled with nonlinear constraint conditions are solved numerically. Time derivatives are approximated by Newmark difference formulae and the resulting nonlinear algebraic equations are solved employing the Newton-Raphson iteration scheme. Several dynamic loads are applied to the center of mass of the tibia and the ensuing motion is investigated. Numerical results on ligament forces, contact point locations between femur and tibia, and the orientation of tibia relative to femur are presented. The results are shown to be consistent with the anatomy of the knee joint.

Three-Body Segment Dynamic Model of the Human Knee

In this paper, a two-dimensional, three-body segment dynamic model of the human knee is introduced. The model includes tibio-femoral and patello-femoral articulations, and anterior cruciate, posterior cruciate, medial collateral, lateral collateral, and patellar ligaments. It enables one to obtain dynamic response of the knee joint to any one or combination of quadriceps femoris, hamstrings, and gastrocnemius muscle actions, as well as any externally applied forces on the lower leg. A specially developed human knee animation program is utilized in order to fine tune some model parameters. Numerical results are presented for knee extension under the impulsive action of the quadriceps femoris muscle group to simulate a vigorous lower limb activity such as kicking. The model shows that the patella can be subjected to very large transient patello-femoral contact force during a strenuous lower limb activity even under conditions of small knee-flexion angles. The results are discussed and compared with limited data reported in the literature.

On the biomechanics of human shoulder complex—I. Kinematics for determination of the shoulder complex sinus

Effectiveness of the multi-segmented total-human-body models to predict realistically live human response depends heavily on the proper biomechanical description and simulation of the major articulating joints of the body. In these models, the most difficult and the least successful modelling of a joint has been the shoulder complex because of the lack of appropriate biomechanical data as well as the anatomical complexity of the region. This paper in Part I presents various aspects of a research program to collect three-dimensional kinematic data for the shoulder complex. A sonic digitizing technique which utilizes an overdeterminate number of sonic emitters on the moving body segment was used for the kinematics analysis. The numerical results are presented for three male subjects for their voluntary shoulder complex sinuses. The results are given in a locally-defined joint axis system as well as in the torso-fixed coordinate system in the form of globographic representation.

Improved Dynamic Model of the Human Knee Joint and Its Response to Impact Loading on the Lower Leg

Almost a decade ago, three-dimensional formulation for the dynamic modeling of an articulating human joint was introduced. Two-dimensional version of this formulation was subsequently applied to the knee joint. However, because of the iterative nature of the solution technique, this model cannot handle impact conditions. In this paper, alternative solution methods are introduced which enable investigation of the response of the human knee to impact loading on the lower leg via an anatomically based model. In addition, the classical impact theory is applied to the same model and a closed-form solution is obtained. The shortcomings of the classical impact theory as applied to the impact problem of the knee joint are delineated.

Biomechanics of normal and abnormal knee joint.

Abstract The investigation reported in this paper is concerned with an experimental and theoretical study conducted to explain the changes of the knee joint mechanics in degenerative joint disease. The major thrust of the study is to determine the resultants of the pressure distribution on both lateral and medial plateaus in normal and abnormal knee joint configurations. Up to 5° of varus and valgus deformity is applied to a normal femorotibial angle of a strain-gaged test specimen which is connected through the femur and the tibia to the jaws of a specially designed loading apparatus. Strains are obtained for various loads and deviated femorotibial angles from the strain gages implanted on the femur and the tibia. Utilization of these strains as data for a three-dimensional theoretical analysis yielded the following results for the normal and abnormal knee joint configurations: (a) contact forces on both lateral and medial plateaus; (b) medial and lateral collateral ligament forces; (c) anteroposterior and lateral-medial moments.

On the biomechanics of human shoulder complex—II. Passive resistive properties beyond the shoulder complex sinus

In multi-segmented total-human-body models the most difficult and the least successful modeling of a major articulating joint has been the shoulder complex because of the lack of appropriate biomechanical data as well as the anatomical complexity of the region. In this paper, quantitative results on the three-dimensional passive resistive properties beyond the voluntary shoulder complex sinus are presented by applying the methodology developed in part I. Constant-restoring-force(moment) contours are established for the shoulder complex and the numerical results are presented for the three subjects tested. In addition, functional expansions are presented for the voluntary and restoring force(moment) contours using spherical coordinates.

Kinematic and force data collection in biomechanics by means of sonic emitters. I: Kinematic data collection methodology

In this paper, first, the principles of sonic digitizing are presented. Next, a description of quantitative determination of the relative motion between two body segments by utilization of sonic emitters is provided. A new kinematic data collection methodology and data analysis is proposed to check continuously the accuracy of the data collected by means of the sonic emitters. The first part of the paper is terminated by establishment of an accuracy criteria and selection of the most accurate data set and associated error analysis. Quantitative results based upon the kinematic data collection methodology of Part I were obtained for the forced kinematic motion of the human shoulder complex and are presented in Part II.

DYNAMIC MODELLING OF HUMAN ARTICULATING JOINTS

Abstract Dynamic simulation of mechanical behavior and response of the total human body to external forces provide essential input for the injury prediction criteria and subsequent design and development of crash protection systems. The most sophisticated versions of the total-human-body models are articulated and multisegmented to simulate all the major articulating joints and segments of the human body. Effectiveness of the multisegmented models to predict accurately live human response depends heavily on the proper biomechanical description and simulation of the articulating joints. This paper is concerned with a mathematical modelling of an articulating joint defined by contact surfaces of two body segments which execute a relative dynamic motion within the constraints of ligament forces. Mathematical equations for the joint model are in the form of second-order nonlinear differential equations coupled with nonlinear algebraic constraint conditions. Differential equations of motion are reduced to a set of nonlinear simultaneous algebraic equations by applying the Newmark method of differential approximation. By subsequent application of Newton—Raphson iteration process the same equations are converted to a set of simultaneous linear algebraic equations. Iteration process is continued until a solution vector of unknowns satisfying a prescribed convergence criterion is obtained. The two-dimensional version of the mathematical joint model is applied to human knee joint for several dynamic loading conditions on tibia. Results for the ligament and contact forces, contact point locations between femur and tibia and the corresponding dynamic orientation of tibia with respect to femur are obtained.

Kinematic and Passive Resistive Properties of Human Elbow Complex

In recent years, owing to their versatility and reduced cost of operation, multisegmented mathematical models of the total human body have gained increased attention in gross biodynamic motion studies. This, in turn, has stimulated the need for a proper biomechanical data base for the major human articulating joints. The lack of such a database for the humero-elbow complex is the impetus for this study. The total angular range of motion permitted by the complex and the passive resistive properties beyond the full elbow extension were studied. Results obtained on ten normal male subjects were utilized to establish a statistical data base for the humero-elbow complex. Results are also expressed in functional expansion form suitable for incorporation into the existing multisegmented models.

Response of a two-dimensional dynamic model of the human knee to the externally applied forces and moments

This paper is concerned with response of a two-dimensional dynamic model of the human knee to the externally applied forces and moments. The profiles of the articulating surfaces of a normal knee joint are determined from X-ray films and they are represented by polynomials. Ligaments of the joint are modelled as nonlinear elastic springs of realistic stiffness properties. Nonlinear equations of motion, coupled with nonlinear constraint conditions, are solved numerically. Time derivatives are approximated by Newmark difference formulae and the resulting nonlinear algebraic equations are solved employing the Newton-Raphson iteration scheme. Several dynamic loads (force and moment) are applied to the tibia and subsequent motion is investigated. Results for the ligament and contact forces, contact point locations between femur and tibia and the corresponding dynamic orientation of tibia with respect to femur are presented.