An Apparatus for Measuring the Load-Displacement and Load-Dependent Kinematic Characteristics of Articulating Joints—Application to the Human Ankle Joint

1980 ◽  
Vol 102 (3) ◽  
pp. 208-213 ◽  
Author(s):  
J. Rastegar ◽  
N. Miller ◽  
R. Barmada
Keyword(s):  
Ankle Joint ◽  
Structural Characteristics ◽  
Accurate Description ◽  
Axis Of Rotation ◽  
Kinematic Characteristics ◽  
Joint Resistance ◽  
Human Ankle ◽  
Load Displacement ◽  
Coupled Loads

An apparatus is described which is capable of measuring the load-displacement characteristics as well as determining the loci of centers of rotation of articulating joints. The apparatus employs a floating head which permits the axis of rotation to coincide with the position of minimum joint resistance, thus eliminating non-physiological rotations at the joint. The coupled loads are also measured, thus providing an accurate description of the joint structural characteristics. Data taken from a freshly amputated human ankle joint is presented.

Effect of Fixed Axes of Rotation on the Varus-Valgus and Torsional Load-Displacement Characteristics of the In-Vitro Human Knee

1979 ◽  
Vol 101 (2) ◽  
pp. 134-140 ◽  
Author(s):  
J. Rastegar ◽  
R. L. Piziali ◽  
D. A. Nagel ◽  
D. J. Schurman
Keyword(s):  
Least Squares ◽  
Cubic Spline ◽  
Nonlinear Load ◽  
Human Knee ◽  
Torsional Load ◽  
Axis Of Rotation ◽  
Second Derivatives ◽  
Load Displacement ◽  
Coupled Loads

The effects of fixed axes of rotation on the varus-valgus and torsional load-displacement characteristics of the human knee have been determined. The location of the axes of varus-valgus and torsional rotations resulting in minimum resisting loads are also determined, and it is shown that they correspond to minimal coupled load levels. The coupled loads are seen to be sensitive to the location of the axis of rotation. The nonlinear load-displacement data is fitted with a four interval least-squares cubic spline with matching first and second derivatives at nodes. The data from two fresh human knees are presented.

The Three-Dimensional Kinematics and Flexibility Characteristics of the Human Ankle and Subtalar Joint—Part II: Flexibility Characteristics

1988 ◽  
Vol 110 (4) ◽  
pp. 374-385 ◽  
Author(s):  
Jie Chen ◽  
Sorin Siegler ◽  
Carson D. Schneck
Keyword(s):  
Ankle Joint ◽  
Angular Displacement ◽  
Three Dimensional ◽  
Anterior Talofibular Ligament ◽  
Neutral Position ◽  
Nonlinear Load ◽  
Highly Nonlinear ◽  
Human Ankle ◽  
Load Displacement

The objective of the present study was to investigate the in-vitro, coupled, three-dimensional load-displacement and flexibility characteristics of the human ankle joint complex consisting of the talocrural and the talocalcaneal joints and to determine the effects that sectioning of the anterior talofibular ligament has on these characteristics. Similar to other anatomical joints such as the knee and the intervertebral joint, the ankle joint complex was found to exhibit highly nonlinear load-displacement characteristics with the angular displacement approaching asymptotic values as the external load was increased. Therefore, a procedure of incremental linearization was used to derive the flexibility characteristics of this structure. According to this procedure, external loads were applied to the calcaneus in small increments and its resulting three dimensional displacements were recorded. The incremental flexibility coefficients were then derived by assuming linear load-displacement relationship for each increment. From the results obtained from fifteen human ankle specimens, it was evident that the ankle joint complex exhibit highly coupled flexibility and load-displacement characteristics. It was further concluded that the ankle joint complex is the most flexible in the neighborhood of the unloaded, neutral position and that all the flexibility coefficients of the structure decrease rapidly toward the extremes of the range of motion. Rupture of the anterior talofibular ligament was found to have a significant effect on the load-displacement and flexibility characteristics of the ankle joint complex. This effect was manifested as a change in the load-displacement characteristics and a large increase in the flexibility coefficients primarily in those corresponding to rotations in the transverse and the coronal plane. The results of the present study can provide the necessary data base for the development of quantitative diagnostic technique for identifying the site and the extent of injury to the collateral ligaments of the ankle.

The Role of the Passive Structures in the Mobility and Stability of the Human Ankle Joint: A Literature Review

2000 ◽  
Vol 21 (7) ◽  
pp. 602-615 ◽  
Author(s):  
Alberto Leardini ◽  
John J. O'Connor ◽  
Fabio Catani ◽  
Sandro Giannini
Keyword(s):  
Literature Review ◽  
Ankle Joint ◽  
Human Ankle

Nonlinear behavior of muscle reflexes at the human ankle joint

1995 ◽  
Vol 73 (1) ◽  
pp. 65-72 ◽  
Author(s):  
R. B. Stein ◽  
R. E. Kearney
Keyword(s):  
Ankle Joint ◽  
Stretch Reflex ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Random Perturbations ◽  
Hydraulic Actuator ◽  
Voluntary Activity ◽  
Highly Nonlinear ◽  
Human Ankle

1. Pulse inputs (similar to tendon jerks) were applied to the human ankle joint with the use of a hydraulic actuator. Inputs of only 1-2 degrees could elicit large responses (> 20% of maximum voluntary contraction). The magnitude of the response depended nonlinearly on a number of factors: the amplitude, direction, and duration of the pulse; the angle of the ankle; and the level of voluntary activation of the ankle muscles. 2. Pulses that flexed or extended the ankle could both produce reflex torques in the same direction (extensor torque). Although an extension of the ankle did not itself produce a response, it could affect the response to a subsequent flexion for up to 1 s. 3. The influence of random perturbations on the stretch reflex at the ankle was assessed. Responses to pulse displacements alone and to pulses superimposed on random perturbations were compared at the same level of voluntary activity. Reflex responses decreased in a graded manner with increasing amplitude or bandwidth of the random perturbations. 4. These results demonstrate that stretch reflexes can generate substantial torques, but in a highly nonlinear manner. In particular, passive joint movements markedly alter stretch reflex gain, and these changes must be considered in interpreting the functional significance of reflex actions.

Functional Electrical Stimulation for Equilibrium-Point Control of Human Ankle Movement: Frequency Domain System Identification of Human Ankle Dynamics

2014 ◽  
Author(s):  
Yuto Yamashita ◽  
Kazuya Maegaki ◽  
Kazuhiro Matsui ◽  
Takanori Oku ◽  
Kanna Uno ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Equilibrium Point ◽  
Ankle Joint ◽  
Movement Analysis ◽  
Human Movement ◽  
Order System ◽  
Force Output ◽  
Mechanical Stiffness ◽  
Human Ankle ◽  
Ankle Movement

This paper presents a novel method for creating an electrical stimulation pattern to control the equilibrium-point (EP) of human ankle movement. Focusing on the synergetic activation of agonist–antagonist (AA) muscles, the proposed method employs the ES-AA ratio (the ratio of the electrical stimulation levels for AA muscles) and the ES-AA sum (the sum of the electrical stimulation levels for AA muscles), which are based on the AA ratio (the ratio of the electromyography (EMG) voltage levels for AA muscles) and the AA sum (the sum of the EMG voltage levels for AA muscles) used in human movement analysis [1, 2]. The ES-AA ratio is related to the EP of the joint whereas the ES-AA sum is associated with mechanical stiffness of the joint. Using the AA concepts, we estimated the transfer function between the input ES-AA ratio (for the tibialis anterior (TA ) and gastrocnemius (GC)) and the force output of the endpoint in the ankle joint in an isometric environment by investigating the frequency characteristics, and finally found that the ankle-joint system was a second-order system with dead time in terms of the ES-AA ratio and foot force.

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