Current models of the musculo-skeletal system fail to accurately predict the relationship between muscle fiber shortening and the relative excursion of the tendino-skeletal interfaces. A simple example of this would be that the tendino-calcaneal interface at the ankle moves approximately 30 mm for a 15 mm soleus muscle fiber shortening. We propose multiple mechanical gain systems to amplify the muscle fiber excursion and the basic design of this proposal is to evaluate these gain systems and determine if they are sufficient to explain the discrepancy between muscle fiber length changes and movement of the ankle. A secondary goal is to understand the underlying mechanics, particularly as it relates to the distortion of muscle tissue during a contraction. The hypotheses to be tested include (1) The proximo-distal displacement of the fiber-aponeurosis interface during an isometric contraction will be due in part to an increase in angle of the interface as well as due to a shortening of the distance between the aponeuroses of insertion and origin, and (2) The proximo-distal displacement of the most distal soleus fiber-aponeurosis of insertion will be less than the linear displacement of the Achilles' tendon insertion point on the calcaneus due to a sling factor that is intrinsic to the musculotendinous-skeletal anatomy. Advanced MR imaging techniques of fiber tracking with Diffusion Tensor Tractography at 3 Tesla, Phase Contrast Imaging, and MRI-compatible dynamometry as well as Finite Element Modeling will be used in combination. This is particularly apt for the PA which asks that a """"""""multidisciplinary research"""""""" with an """"""""integration of principles from a diversity of technical and biomedical field"""""""" be used to """"""""provide new understanding"""""""" and """"""""effectively address a biomedical problem"""""""". We will experimentally investigate several design features of the Triceps Surae Complex that could account for apparent paradoxes in current descriptions of muscle performance and generate a model consistent with our experimental observations. Our goal is better prediction of intrinsic muscle properties and joint performance. Essential variables that we will measure to test these hypotheses include muscle volume, muscle surface area, fiber orientation, aponeurosis separation (muscle thickness), aponeurosis dimension and strain properties of aponeurosis. In 3Dal space, these variables will be quantified at systematically varying ankle joint positions and muscle activation levels. From a past grant from NASA/NSBRI, we have had considerable success in developing most of these relatively difficult techniques, (as per publications in Appendix). The developed model will help to gain better insight into the design features of muscle-tendon complex, a better understanding of chronic muscle adaptations such as disuse atrophy and better prediction of outcomes of surgical treatments such as aponeurotomy, tenectomy and tenotomy. ? ?

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
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Special Emphasis Panel (ZRG1-MOSS-K (03))
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Lester, Gayle E
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University of California San Diego
Schools of Medicine
La Jolla
United States
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Sinha, Shantanu; Sinha, Usha; Malis, Vadim et al. (2018) Exploration of male urethral sphincter complex using diffusion tensor imaging (DTI)-based fiber-tracking. J Magn Reson Imaging 48:1002-1011
Kinugasa, Ryuta; Taniguchi, Keigo; Yamamura, Naoto et al. (2018) A Multi-modality Approach Towards Elucidation of the Mechanism for Human Achilles Tendon Bending During Passive Ankle Rotation. Sci Rep 8:4319
Malis, Vadim; Sinha, Usha; Csapo, Robert et al. (2018) Relationship of changes in strain rate indices estimated from velocity-encoded MR imaging to loss of muscle force following disuse atrophy. Magn Reson Med 79:912-922
Malis, Vadim; Sinha, Usha; Csapo, Robert et al. (2018) Diffusion tensor imaging and diffusion modeling: Application to monitoring changes in the medial gastrocnemius in disuse atrophy induced by unilateral limb suspension. J Magn Reson Imaging :
Sinha, Usha; Malis, Vadim; Csapo, Robert et al. (2018) Shear strain rate from phase contrast velocity encoded MRI: Application to study effects of aging in the medial gastrocnemius muscle. J Magn Reson Imaging 48:1351-1357
Ugarte, Vincent; Sinha, Usha; Malis, Vadim et al. (2017) 3D multimodal spatial fuzzy segmentation of intramuscular connective and adipose tissue from ultrashort TE MR images of calf muscle. Magn Reson Med 77:870-883
Chen, Jiun-Shyan; Basava, Ramya Rao; Zhang, Yantao et al. (2016) Pixel-based meshfree modelling of skeletal muscles. Comput Methods Biomech Biomed Eng Imaging Vis 4:73-85
Sinha, Usha; Csapo, Robert; Malis, Vadim et al. (2015) Age-related differences in diffusion tensor indices and fiber architecture in the medial and lateral gastrocnemius. J Magn Reson Imaging 41:941-53
Sinha, Usha; Malis, Vadim; Csapo, Robert et al. (2015) Age-related differences in strain rate tensor of the medial gastrocnemius muscle during passive plantarflexion and active isometric contraction using velocity encoded MR imaging: potential index of lateral force transmission. Magn Reson Med 73:1852-63
Csapo, Robert; Malis, Vadim; Sinha, Usha et al. (2015) Mapping of spatial and temporal heterogeneity of plantar flexor muscle activity during isometric contraction: correlation of velocity-encoded MRI with EMG. J Appl Physiol (1985) 119:558-68

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