The Role of Electromyograms in Resolving Musculoskeletal Interactions in Able-Bodied and Disabled Human Individuals

Mizrahi, J.

doi:10.5772/24977

Cited by 3 publications

(1 citation statement)

References 49 publications

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“…However, we believe that using the optimization criterion with the least TFCF prediction error, and constraining it further to match the actual in vivo TFCF, provides the best currently possible estimation of muscle forces at the knee. Further studies which, additionally to the in vivo JCFs, also use comprehensive EMG measurements as boundary conditions to further constrain the solution space could provide even more realistic muscle force estimations [ 51 ]. While our small cohort of TKR patients cannot represent all habitual and cultural variations of human locomotion, it is still the largest group worldwide in which in vivo measurements of the TFCF are possible.…”

Section: Discussionmentioning

confidence: 99%

Impact of antagonistic muscle co-contraction on in vivo knee contact forces

Trepczynski

Kutzner

Schwachmeyer

et al. 2018

J NeuroEngineering Rehabil

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BackgroundThe onset and progression of osteoarthritis, but also the wear and loosening of the components of an artificial joint, are commonly associated with mechanical overloading of the structures. Knowledge of the mechanical forces acting at the joints, together with an understanding of the key factors that can alter them, are critical to develop effective treatments for restoring joint function. While static anatomy is usually the clinical focus, less is known about the impact of dynamic factors, such as individual muscle recruitment, on joint contact forces.MethodsIn this study, instrumented knee implants provided accurate in vivo tibio-femoral contact forces in a unique cohort of 9 patients, which were used as input for subject specific musculoskeletal models, to quantify the individual muscle forces during walking and stair negotiation.ResultsEven between patients with a very similar self-selected gait speed, the total tibio-femoral peak forces varied 1.7-fold, but had only weak correlation with static alignment (varus/valgus). In some patients, muscle co-contraction of quadriceps and gastrocnemii during walking added up to 1 bodyweight (~ 50%) to the peak tibio-femoral contact force during late stance. The greatest impact of co-contraction was observed in the late stance phase of stair ascent, with an increase of the peak tibio-femoral contact force by up to 1.7 bodyweight (66%).ConclusionsTreatment of diseased and failed joints should therefore not only be restricted to anatomical reconstruction of static limb axes alignment. The dynamic activation of muscles, as a key modifier of lower limb biomechanics, should also be taken into account and thus also represents a promising target for restoring function, patient mobility, and preventing future joint failure.Trial registrationGerman Clinical Trials Register: ID: DRKS00000606, date: 05.11.2010.Electronic supplementary materialThe online version of this article (10.1186/s12984-018-0434-3) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Impact of antagonistic muscle co-contraction on in vivo knee contact forces

Trepczynski

Kutzner

Schwachmeyer

et al. 2018

J NeuroEngineering Rehabil

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Mechanical Impedance and Its Relations to Motor Control, Limb Dynamics, and Motion Biomechanics

Mizrahi

2015

J. Med. Biol. Eng.

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The concept of mechanical impedance represents the interactive relationship between deformation kinematics and the resulting dynamics in human joints or limbs. A major component of impedance, stiffness, is defined as the ratio between the force change to the displacement change and is strongly related to muscle activation. The set of impedance components, including effective mass, inertia, damping, and stiffness, is important in determining the performance of the many tasks assigned to the limbs and in counteracting undesired effects of applied loads and disturbances. Specifically for the upper limb, impedance enables controlling manual tasks and reaching motions. In the lower limb, impedance is responsible for the transmission and attenuation of impact forces in tasks of repulsive loadings. This review presents an updated account of the works on mechanical impedance and its relations with motor control, limb dynamics, and motion biomechanics. Basic questions related to the linearity and nonlinearity of impedance and to the factors that affect mechanical impedance are treated with relevance to upper and lower limb functions, joint performance, trunk stability, and seating under dynamic conditions. Methods for the derivation of mechanical impedance, both those for within the system and material–structural approaches, are reviewed. For system approaches, special attention is given to methods aimed at revealing the correct and sufficient degree of nonlinearity of impedance. This is particularly relevant in the design of spring-based artificial legs and robotic arms. Finally, due to the intricate relation between impedance and muscle activity, methods for the explicit expression of impedance of contractile tissue are reviewed.

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