Influence Of Muscle Loading Research Articles

Elongation patterns of the collateral ligaments of the human knee

Objective. To determine the responses of the medial and lateral collateral ligaments (MCL, LCL) of the human knee to externally applied stresses. Design. Differential variable reluctance transducers were used to measure length changes along the long posterior parallel fibers of the MCL and the middle third of the LCL through a flexion range of 15–120 ° and a variety of external stresses. Background. There is a lack of consensus regarding the collateral ligament response to internal and external tibial rotation. In addition, there are very few studies that have investigated the effects of quadriceps and hamstrings muscle group loads on the strain in the collateral ligaments. Methods. Three series of tests were performed. First, the passive behavior of the ligaments was obtained as well as the ligament response to 3 ° of varus and valgus rotation. The next series tested the ligaments' response to 0–10 ° of internal and external tibial axial rotation. Finally, isolated and co-contracted quadriceps and hamstrings muscle group loads were applied. Results. The instrumented portions of both ligaments were more strained in extension than flexion. Varus rotations stretched the LCL, whereas valgus rotations elongated the MCL. The strain in the MCL was shown to increase during external rotation and decrease during internal rotation. The LCL did not exhibit a uniform response across specimens to internal or external tibial axial rotation, but was consistent between left and right knees from a single cadaver. Highly consistent trends of interactions between muscle loads and the strain in both the MCL and LCL were noted. Conclusions. The responses of the MCL and LCL to applied stresses are dependent upon the flexion angle of the knee, the influence of muscle loading and, to a lesser extent, anatomic variation in the ligaments themselves. Guidelines for rehabilitation of the collateral ligaments following injury are suggested.

A kinematical study of the human wrist joint in vitro

s of the Fourth Meeting of the European Society of Biomechanics 531 The results consisted of floor reaction forces; moments, forces and deflections at the ends of the structure’s members. These were compared to data of foot-ground pressure distributions (FGP) and deflections measured on radiographs of standing subjects. A KINEMATICAL STUDY OF THE HUMAN WRIST JOINT IN VITRO A. DE LANGE, M. SCHREIBERS, R. HUISKES, J. M. G. KAUER and H. WOLTRING (Musculoskeletal Research Section, Department of Anatomy, and Biomechanics Section, Laboratory for Experimental Orthopaedics, University of Nijmegen, The Netherlands) For providing more insight into the carpal bone behaviour, useful in clinical diagnosis and several reconstruction procedures, detailed and precise quantitative three-dimensional kinematic descriptions of the individual carpal bones in several prescribed hand motions were obtained, using a Roentgen-stereophotogrammetric method. The relative motions were assessed in terms of Euler rotation angles and translation vectors and of finite helical axes. Tests were repeated several times, in order to investigate the reproducibility, influence of muscle loading, of supinated vs pronated motion pathways and other external effects. Precision analyses revealed low errors (0.348”) in the rotation angles in contrast to those in the helical axis representations. However, after using a mathematical fitting procedure on the row marker position data, consistent axis patterns could be obtained. The obtained kinematic information may serve as a database for future developments of functional wrist-joint models. SCREW THEORY AND ITS APPLICATIONS TO JOINT MOTION ANALYSIS STEVEN PETERSON and ARTHUR ERDMAN (University of Minnesota, Minneapolis, MN, U.S.A.) The measurement of skeletal joint motion plays an important role in biomechanical analysis. Traditionally, motion analysis has concerned itself with finding the screw axis of the motion. These screw axes are used to model the joint using standard machine joints. The models produced using these techniques tend to oversimplify the true motion of the joint, and provide little information about the physiologic constraints which produce the motion. In the late 1800s kinematicians developed a theory--called screw theory-which describes the relationship between forces being applied to a rigid body and the motion they produce. This paper describes a method for calculating the displacement parameters for a rigid body using screw algebra. The influence of measurement errors on these calculations will also be presented. ‘SCREW HOME’ MECHANISM OF THE KNEE DURING WALKING MARIO A. LAFORTUNE and PETER R. CAVANAGH (Universitt du Quebec a Trois-Rivikres, Quebec, Canada) Steinmann traction pins were inserted into the femur, patella and tibia of five symptom-free volunteers. Radioopaque spheres were attached to the intra-cortical pins. The location of the spheres with respect to the bone frames of reference and to an external frame of reference were obtained using the Direct Linear Transformation and either X-ray or film recordings. The motions of the knee joint were described by the following clinical motions: shift, drawer, distraction, flexion-extension, ab-adduction and rotation. Twice during the gait cycle the knee approached or reached maximal extension. Only one subject showed external rotation during the stance phase and, during the swing phase the external rotation even began when knee flexion was underway. The results of the present study generally do not support the concept of ‘screw-home’ mechanism during walking. A THREE-DIMENSIONAL KINEMATIC ACQUISITION AND INTERSEGMENTAL DYNAMIC ANALYSIS SYSTEM FOR HUMAN MOTION E. K. ANTONSSON and R. W. MANN (Massachusetts Institute of Technology, Cambridge, MA, U.S.A.) A new system for automatic accumulation and reduction of three-dimensional, human kinematic data has been designed and implemented. Three-dimensional linkage analysis methods are introduced to describe completely the positions and orientations, and estimate the total moments and net forces between links, including a momentary axis of rotation solution to objectively locate joint axes. Kinematic data acquisition is accomplished by a Selspot infra-red, opto-electronic device with thirty LED markers sampled by two cameras. Sets of markers are grouped in segment oriented, rigid arrays each with an imbedded body coordinate system. The calibration and frequency response are completely characterized, as well as worst case estimates of error bounds in the kinematics and dynamics. The double differentiated kinematic data yields no more than 5% error in the dynamics.