Static optimization of muscle forces during the stance phase of the normal gait including the physiological properties of muscle in the objective function

2007 ◽  
Vol 10 (sup1) ◽  
pp. 59-60 ◽  
Author(s):  
A. Bonnefoy ◽  
R. Dumas ◽  
N. Doriot ◽  
M. Senk ◽  
D. Pradon ◽  
...  
Keyword(s):  
Objective Function ◽  
Stance Phase ◽  
Muscle Forces ◽  
Static Optimization ◽  
Normal Gait ◽  
Physiological Properties

An Analytical Examination of Muscle Force Estimations Using Optimization Techniques

1993 ◽  
Vol 207 (3) ◽  
pp. 139-148 ◽  
Author(s):  
J H Challis ◽  
D G Kerwin
Keyword(s):  
Objective Function ◽  
Muscle Force ◽  
Human Movement ◽  
Optimization Techniques ◽  
Muscle Model ◽  
Muscle Forces ◽  
Objective Functions ◽  
Physiological Properties ◽  
Maximal Activation

Muscle forces are often estimated during human movement using optimization procedures. The optimization procedures involve the minimization of an objective function relating to the muscle forces. In this study 15 different objective functions were evaluated by examining the analytical solutions to the objective functions and by comparing their force predictions with the forces estimated using a validated muscle model. The muscle forces estimated by the objective functions were shown to give poor correspondence with the muscle model predicted muscle forces. The objective function estimates were criticized for not taking sufficient account of the physiological properties of the muscles. As a consequence of the analysis of the objective functions an alternative, simpler function was presented with which to estimate muscle forces in vivo. This function required that to satisfy a given joint moment, the force exerted by each of the muscles divided by the maximum force possible by the muscle was constant for all muscles. For this function the maximum muscle force was determined using a muscle model assuming maximal activation.

INVESTIGATION OF THE INFLUENCE OF THE ELBOW JOINT REACTION ON THE PREDICTED MUSCLE FORCES USING DIFFERENT OPTIMIZATION FUNCTIONS

2009 ◽  
Vol 12 (01) ◽  
pp. 31-43 ◽  
Author(s):  
Rositsa T. Raikova
Keyword(s):  
Objective Function ◽  
Elbow Joint ◽  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Biomechanical Model ◽  
Moment Equation ◽  
Muscle Forces ◽  
Joint Stability ◽  
Biarticular Muscles ◽  
Joint Reaction

Less attention is paid to joint reactions when optimization tasks are solved aiming to predict individual muscle forces driving a biomechanical model. The reactions are important, however, for joint stability and for prevention from injuries, especially for fast motions and submaximal loading. The purpose of the paper is to investigate the influence of the joint reaction as a criterion in an objective function and to study the possibilities for prediction of antagonistic co-contraction. Planar elbow flexions in the sagittal plane with duration from 0.4 to 2 s are simulated, and muscle forces and elbow joint reaction are calculated solving numerically optimization tasks formulated for models with one (elbow moment equation only) and two (elbow and shoulder moment equations) degrees of freedom (DOF). The objective function is a weighted sum of muscle forces and joint reaction raised to different powers. The following conclusions can be made: (1) if the joint reaction is included in the objective function, antagonistic co-contraction can be predicted even for 1 DOF model; in some situations the use of such objective function can destroy the synergistic muscles' action; (2) the prediction of antagonistic muscles' co-contraction for 2 DOF model depends on the way the biarticular muscles are modeled, and this is valid for both dynamic and quasistatic conditions; if there are no biarticular muscles, antagonistic co-contraction cannot be predicted in one joint using popular objective functions, like minimum of sum of muscle forces or muscle stresses raised to a power.

scholarly journals Newly designed computer controlled knee-ankle-foot orthosis (Intelligent Orthosis)

1998 ◽  
Vol 22 (3) ◽  
pp. 230-239 ◽  
Author(s):  
T. Suga ◽  
O. Kameyama ◽  
R. Ogawa ◽  
M. Matsuura ◽  
H. Oka
Keyword(s):  
Lower Limb ◽  
Stance Phase ◽  
Gait Cycle ◽  
Normal Subjects ◽  
Swing Phase ◽  
Ankle Foot Orthosis ◽  
Normal Gait ◽  
Heel Contact ◽  
Computer Controlled ◽  
Foot Orthosis

The authors have developed a knee-ankle-foot orthosis with a joint unit that controls knee movements using a microcomputer (Intelligent Orthosis). The Intelligent Orthosis was applied to normal subjects and patients, and gait analysis was performed. In the gait cycle, the ratio of the stance phase to the swing phase was less in gait with the knee locked using a knee-ankle-foot orthosis than in gait without an orthosis or gait with the knee controlled by a microcomputer. The ratio of the stance phase to the swing phase between controlled gait and normal gait was similar. For normal subjects the activity of the tibialis anterior was markedly increased from the heel-off phase to the swing phase in locked gait. The muscle activities of the lower limb were lower in controlled force in locked gait showed spikes immediately after heel-contact in the vertical at heel-contact in the sagittal to locked gait, gait with the Intelligent Orthosis is smooth and close to normal gait from the viewpoint of biomechanics. Even in patients with muscle weakness of the quadriceps, control of the knee joint using the Intelligent Orthosis resulted in a more smooth gait with low muscle discharge.

Mechanical Stress Patterns in the Human Proximal Tibial Growth Plate During the Stance Phase of Normal Gait

2002 ◽  
Author(s):  
Amy L. Lerner ◽  
David L. Gushue ◽  
Emily A. Gedbaw
Keyword(s):  
Growth Plate ◽  
Stance Phase ◽  
Bone Growth ◽  
Proximal Tibia ◽  
Material Model ◽  
Growth Disorders ◽  
Loading Conditions ◽  
Normal Gait ◽  
Poroelastic Material ◽  
Stress Patterns

Since the mid 1800’s clinicians and researchers have considered the effect of mechanical stresses on bone growth and the development of growth disorders [1]. However, the specifics of this relationship remain poorly understood. Both clinical and experimental evidence support the concept that magnitude, frequency and duration of loads are critical in defining the response of cartilage to pressures [2, 3]. Yet, the range of physiologic pressures in the growth plate has not been identified, and most models of growing bones have considered single quasi-static loading conditions and/or elastic material models that can not accurately represent time dependence [4, 5]. It was the goal of this study to implement loading conditions representing an entire stance phase of gait in a two-dimensional model of the proximal tibia of a normal child. A poroelastic material model was used in order to identify the variations in growth plate pressures in both time and location, and investigate the potential for fluid flow within the growth plate.

Musculoskeletal Model of the Human Knee With Representation of Menisci During the Stance Phase of a Walk Cycle

2012 ◽  
Author(s):  
Mohammad Kia ◽  
Trent M. Guess ◽  
Antonis Stylianou
Keyword(s):  
Knee Joint ◽  
Stance Phase ◽  
Musculoskeletal Model ◽  
Musculoskeletal Modeling ◽  
Ground Reaction Forces ◽  
Forward Dynamics ◽  
Muscle Forces ◽  
Human Knee ◽  
Reaction Forces ◽  
Movement Simulation

Movement simulation and musculoskeletal modeling can predict muscle forces, but current methods are hindered by simplified representations of joint structures. Simulations that incorporate muscle forces, an anatomical representation of the natural knee, and contact mechanics would be a powerful tool in orthopedics. This study combined a validated anatomical model of a knee joint with menisci and a musculoskeletal model of the human lower extremity. A forward-dynamics muscle driven simulation of the stance phase of a walk cycle was simulated in LifeMOD (Lifemodeler, Inc) and muscle forces and ground reaction forces were estimated. The predicted forces were evaluated using test data provided by Vaughan CL. et al. (1999).

Development and Functional Testing of An Unloading Concept for Knee Osteoarthritis Patients: A Pilot Study

2021 ◽  
Author(s):  
Jonas Stensgaard Stoltze ◽  
Jari Pallari ◽  
Behrokh Eskandari ◽  
Anderson S. Oliveira ◽  
Cristina I. Pirscoveanu ◽  
...  
Keyword(s):  
Knee Osteoarthritis ◽  
Healthy Subject ◽  
Muscle Activation ◽  
Stance Phase ◽  
Experimental Tests ◽  
Functional Testing ◽  
Joint Force ◽  
Normal Gait ◽  
Musculoskeletal Models ◽  
Clinical Experiments

Abstract This paper presents a knee brace design that applies an extension moment to unload the muscles in stance phase during gait, and thereby the knee, as alternative to conventional valgus braces for knee osteoarthritis patients. The concept was tested on one healthy subject during normal gait with a prototype, which was designed to activate and deactivate in order to apply the extension moment in the stance phase only and hereby avoid any interference during the swing phase. Electromyography measurements and musculoskeletal models were used to evaluate the brace effects on muscle activation and knee compressive forces respectively. Simulations predicted an ideal reduction of up to 36%, whereas experimental tests revealed a reduction of up to 24% with the current prototype. The prototype brace also reduced the knee joint force impulse up to 9% and EMG peak signal of the vasti muscles with up to 19%. Due to these reductions on a healthy subject, this bracing approach seem promising for reducing knee loads during normal gait. However, further clinical experiments on knee osteoarthritis patients are required to evaluate the effect on both pain and disease progression.

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