Calculation of muscle forces during normal gait under consideration of femoral bending moments.
This paper introduces a new approach for computing lower extremity muscle forces by incorporating equations that consider "bone structure" and "prevention of bending by load reduction" into existing optimization algorithms. Lower extremity muscle and joint forces, during normal gait, were calculated and compared using two different optimization approaches. We added constraint equations that prevent femoral bending loads to an existing approach that considers "minimal total muscular force". Gait parameters such as kinematics, ground reaction forces, and surface electromyographic activation patterns were examined using standardized gait analysis. A subject-specific anatomic model of the lower extremities, obtained from magnetic resonance images of a healthy male, was used for the simulations. Finite element analysis was used to calculate femoral loads. The conventional method of calculating muscle forces leads to higher rates of femoral bending and structural stress than the new approach. Adding equations with structural subject-specific parameters in our new approach resulted in reduced femoral stress patterns. These findings show that our new approach improves the accuracy of femoral stress and strain simulations. Structural overloads caused by bending can be avoided during inverse calculation of muscle forces.
Department of Computer Science and Engineering, Frankfurt University of Applied Sciences, Frankfurt/Main, Germany. Electronic address: fredericklutz@web.de.
Frederick
F
Lutz
Department of Mechanical Engineering, University of Applied Sciences, Esslingen, Germany.
Roland
R
Mastel
Aerpah-Clinic Esslingen-Kennenburg, Esslingen, Germany.
Martin
M
Runge
Orthopedic University Hospital Friedrichsheim gGmbH, Frankfurt/Main, Germany.
Felix
F
Stief
Experimental Orthopedics & Trauma Surgery, Frankfurt Initiative for Regenerative Medicine, Johann-Wolfgang-Goethe-Universität, Frankfurt/Main, Germany.
André
A
Schmidt
Orthopedic University Hospital Friedrichsheim gGmbH, Frankfurt/Main, Germany.
Andrea
A
Meurer
Department of Biomechatronics, Ilmenau University of Technology, Ilmenau, Germany.
Hartmut
H
Witte
D001696:Biomechanical Phenomena; D005269:Femur / Q000502:physiology*; D020342:Finite Element Analysis; D005684:Gait; D006801:Humans; D009068:Movement; D018482:Muscle, Skeletal / Q000502:physiology*; D013314:Stress, Mechanical
Femoral bending; Inverse dynamics; Muscle forces; Musculoskeletal simulation