Modeling of Multiarticular Muscles: Importance of Inclusion of Tendon-Pulley Interactions in the Finger

• Published in: IEEE transactions on biomedical engineering Vol. 56; no. 9; pp. 2253 - 2262
• Main Authors: Lee, Sang Wook, Kamper, Derek G.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.09.2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Algorithms; Biomechanical Phenomena - physiology; Dynamics; Electric Stimulation; finger; Finger Joint - physiology; Fingers; Fingers - physiology; hand; Humans; In vivo; Injuries; joint coordination; Male; Mechanical Phenomena; Models, Biological; moment arm (MA); Motor drives; Muscle, Skeletal - physiology; Muscles; Protocols; pulley; Pulleys; Reproducibility of Results; Solid modeling; Tendons; Tendons - physiology; Torque
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2009.2019119

The purpose of this study was to examine force transmission from one of the major multi-articular muscles of the finger, flexor digitorum pro-fundus (FDP), to the index finger. Specifically, we examined whether the popular moment arm (MA)-joint torque technique of modeling muscle force transmission can accurately represent the effects of the FDP on finger movement. A dynamic finger model employing geometric MA values (model I) was compared with another model including realistic tendon force transformation mechanisms via pulley structures and joint reaction forces (model II). Finger flexion movements generated by these models were compared with those obtained from in vivo stimulation experiments. The model with the force transformation mechanisms (model II) resulted in more realistic joint spatial coordination (i.e., proximal interphalangeal > metacarpophalangeal ges distal interphalangeal) than the MA-based model (model I) in relation to the movement patterns evoked by stimulation. Also, the importance of the pulley structures and passive joint characteristics was confirmed in the model simulation; altering/eliminating these components significantly changed the spatial coordination of the joint angles during the resulting movements. The results of this study emphasize the functional importance of the force transformation through various biomechanical components, and suggest the importance of including these components when investigating finger motor control, such as for examining injury mechanisms or designing rehabilitation protocols.