Influences of Speed and Treadmill Inclination on the Local Dynamic Stability of Human Knee Joint

2018 ◽  
Vol 880 ◽  
pp. 130-135 ◽  
Author(s):  
Marius Georgescu ◽  
Alin Petcu ◽  
Daniela Tarniţă
Keyword(s):  
Dynamic Stability ◽  
Knee Joints ◽  
Single Subject ◽  
Local Dynamic ◽  
Human Knee ◽  
Finite Time Lyapunov Exponents ◽  
Local Dynamic Stability ◽  
Human Knee Joint ◽  
Flexion Extension ◽  
Experimental Time Series

In this paper finite-time Lyapunov exponents (LE) were estimated to quantify the local dynamic stability from the experimental time series of the flexion-extension angle of single subject knee joints, walking over-ground and on plane and inclined treadmill with different speeds and inclinations.

Local Dynamic Stability Versus Kinematic Variability of Continuous Overground and Treadmill Walking

2000 ◽  
Vol 123 (1) ◽  
pp. 27-32 ◽  
Author(s):  
J. B. Dingwell ◽  
J. P. Cusumano ◽  
P. R. Cavanagh ◽  
D. Sternad
Keyword(s):  
Dynamic Stability ◽  
Finite Time ◽  
Local Stability ◽  
Neuromuscular Control ◽  
Treadmill Walking ◽  
Local Dynamic ◽  
Kinematic Data ◽  
Finite Time Lyapunov Exponents ◽  
Gait Kinematics ◽  
Local Dynamic Stability

This study quantified the relationships between local dynamic stability and variability during continuous overground and treadmill walking. Stride-to-stride standard deviations were computed from temporal and kinematic data. Maximum finite-time Lyapunov exponents were estimated to quantify local dynamic stability. Local stability of gait kinematics was shown to be achieved over multiple consecutive strides. Traditional measures of variability poorly predicted local stability. Treadmill walking was associated with significant changes in both variability and local stability. Thus, motorized treadmills may produce misleading or erroneous results in situations where changes in neuromuscular control are likely to affect the variability and/or stability of locomotion.

To What Extent Does Not Wearing Shoes Affect the Local Dynamic Stability of Walking?: Effect Size and Intrasession Repeatability

2014 ◽  
Vol 30 (2) ◽  
pp. 305-309 ◽  
Author(s):  
Philippe Terrier ◽  
Fabienne Reynard
Keyword(s):  
Dynamic Stability ◽  
Effect Size ◽  
Intraclass Correlation ◽  
Clinical Findings ◽  
Local Dynamic ◽  
Gait Stability ◽  
Local Dynamic Stability ◽  
Gait Parameters ◽  
Absolute Agreement ◽  
The Stability

Local dynamic stability (stability) quantifies how a system responds to small perturbations. Several experimental and clinical findings have highlighted the association between gait stability and fall risk. Walking without shoes is known to slightly modify gait parameters. Barefoot walking may cause unusual sensory feedback to individuals accustomed to shod walking, and this may affect stability. The objective was therefore to compare the stability of shod and barefoot walking in healthy individuals and to analyze the intrasession repeatability. Forty participants traversed a 70 m indoor corridor wearing normal shoes in one trial and walking barefoot in a second trial. Trunk accelerations were recorded with a 3D-accelerometer attached to the lower back. The stability was computed using the finite-time maximal Lyapunov exponent method. Absolute agreement between the forward and backward paths was estimated with the intraclass correlation coefficient (ICC). Barefoot walking did not significantly modify the stability as compared with shod walking (average standardized effect size: +0.11). The intrasession repeatability was high (ICC: 0.73–0.81) and slightly higher in barefoot walking condition (ICC: 0.81–0.87). Therefore, it seems that barefoot walking can be used to evaluate stability without introducing a bias as compared with shod walking, and with a sufficient reliability.

Effect of Load Carrying on Local Dynamic Stability

2007 ◽  
Vol 51 (15) ◽  
pp. 909-913 ◽  
Author(s):  
Jian Liu ◽  
Thurmon E. Lockhart ◽  
Kevin Granata
Keyword(s):  
Dynamic Stability ◽  
Load Condition ◽  
Local Dynamic ◽  
Fall Injuries ◽  
Local Dynamic Stability ◽  
Load Carrying ◽  
Trunk Acceleration ◽  
The Stability ◽  
Major Factors

Occupational load carrying tasks are considered one of the major factors contributing to slip and fall injuries. The objective of the current study was to explore the feasibility to assess the stability changes associated with load carrying by local dynamic stability measures. Twenty-five young participants were involved in a treadmill walking study, with their trunk acceleration profiles measured wirelessly by a tri-axial accelerometer. Finite time local dynamic stability was quantified by maximum Lyapunov exponents (maxLE). The results showed a significant increase in long term maxLE in load condition, indicating the declined local dynamic stability due to the load carrying. Thus, current study confirmed the discriminative validity and sensitivity of local dynamic stability measure and its utility in the load carrying scenario.

A New Load Application System for In Vitro Study of Ligamentous Injuries to the Human Knee Joint

1995 ◽  
Vol 117 (4) ◽  
pp. 373-382 ◽  
Author(s):  
J. M. Bach ◽  
M. L. Hull
Keyword(s):  
Knee Joint ◽  
Degree Of Freedom ◽  
Load Application ◽  
Accuracy Evaluation ◽  
Application System ◽  
Human Knee ◽  
Human Knee Joint ◽  
Flexion Extension ◽  
External Loads

This paper describes the design and accuracy evaluation of a new six degree of freedom load application system for in vitro testing of the human knee joint. External loads of both polarity in all six degrees of freedom can be applied either individually or in any combination while the knee is permitted to move unconstrained in response to applied loads. The flexion/extension degree of freedom permits the full physiological range of motion. In addition to external loads, forces of the three major muscle groups (quadriceps, hamstrings, gastrocnemius) crossing the joint can be developed. Full automation and rapid convergence of loads to programmed values are achieved through a computer which feeds command signals to servo controller/electro-pneumatic servo valves. The servo valves regulate pressure to pneumatic actuators which develop the various loads. Experiments undertaken to quantify the accuracy of both load and displacement measurements reveal that errors particularly in load measurement are effectively controlled through the apparatus design.

Finite Element Model of the Human Knee Joint to Study Tibio-Femoral Contact Mechanics

2000 ◽  
Author(s):  
Tammy Haut Donahue ◽  
Maury L. Hull ◽  
Mark M. Rashid ◽  
Christopher R. Jacobs
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Degrees Of Freedom ◽  
Soft Tissues ◽  
Element Model ◽  
Human Knee ◽  
Human Knee Joint ◽  
Solid Models ◽  
Flexion Extension ◽  
A New Technique

Abstract A finite element model of the tibio-femoral joint in the human knee was created using a new technique for developing accurate solid models of soft tissues (i.e. cartilage and menisci). The model was used to demonstrate that constraining rotational degrees of freedom other than flexion/extension when the joint is loaded in compression markedly affects the load distribution between the medial and lateral sides of the joint. The model also was used to validate the assumption that the bones can be treated as rigid.

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