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==== Ten Simple Rules Example ====
== Full Body Musculoskeletal Model for Muscle-Driven Simulation of Human Gait ==

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Background: Musculoskeletal models provide a non-invasive means to study human movement and predict the effects of interventions on gait. This study describes the validation of an open-source 3-D musculoskeletal model with high-fidelity representations of the lower limb musculature of healthy young individuals that can be used to generate accurate simulations of gait.

''Disclaimer: This example does not necessarily demonstrate the level of detail required to fully satisfy the Committee’s credibility guidelines [1]. The granularity of how each rule is applied is solely dependent on the needs of each modeling and simulation project.''
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'''Rule 1: Define context clearly'''
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 * Domain of Use: Fundamental research
 * Use Capacity:  This is an open-source, three-dimensional musculoskeletal model that:
      * Has high-fidelity representations of the lower limb musculature of '''healthy, young adult individuals'''
      * Is '''computationally fast''' enough for use in muscle-driven simulations

 * Strength of Influence: Is suitable for simulating '''normal gait''' -- specifically for walking and jogging/running, but should be tested before use for activities that require high knee flexion such as sprinting and cycling


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'''Rule 2: Use appropriate data'''
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 * Data used to develop the model include 1) motion capture data from 41 retro-reflective markers tracked at 100 Hz using an eight-camera motion capture system; 2) ground reaction forces and moments measured at 2000 Hz using over-ground force plates; 3) musculotendon parameters derived from previous anatomical measurements of 21 cadaver specimens and magnetic resonance images of 24 young healthy subjects

 * Expected variability in the data is provided in Supplemental Table I of Rajagopal et al. [2]

 * Data used to validate the model: Experimental electromyography (EMG) data for the gluteus maximus, gluteus minimus, rectus femoris, vastus lateralis, biceps femoris long head, gastrocnemius lateralis, tibialis anterior, and soleus

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'''Rule 3: Evaluate within context'''
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 * Tested model fidelity criteria by: 1) qualitative comparison of musculoskeletal geometry of the model to experimental data; 2) quantitative and qualitative verification of simulated muscle-generated joint moments to inverse dynamics joint moments; 3) qualitative validation of simulated muscle activity to EMG data

 * Comprehensive testing and sensitivity analysis are still needed.

 * Tested computational speed by comparing the speed of the Full Body Model to generate a single gait cycle simulation relative to other frequently used musculoskeletal models.

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'''Rule 4: List limitations explicitly'''
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 * Model does not contain representations of all lower limb muscles or representations of ligaments or other soft tissues. 
 * Chosen musculotendon parameters represent an average individual based on experimental data from literature, and these data contain variability, which is not captured in the model.
 * It is assumed that as a muscle-tendon unit changes length, all fibers in the muscle change length equally.
 * Model tested within defined ranges of motion: 40° plantarflexion to 30° dorsiflexion; 0° to 120° knee flexion; 30° hip extension to 120° hip flexion; 50° hip abduction to 30° hip adduction; and 40° hip external rotation to 40° hip internal hip rotation.
 * Users should always test within kinematic space the model will be used – particularly for movement with higher knee flexion angles.

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'''Rule 5: Use version control'''
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 All versions of the model, associated data, and documentation are managed using the subversion repository provided at [[https://simtk.org/projects/full_body|SimTK]].

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'''Rule 6: Document adequately'''
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 All associated documentation (e.g., readme file) and publications are freely available for download from the [[https://simtk.org/projects/full_body|project website at SimTK]].

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'''Rule 7: Disseminate broadly'''
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 The model, data used to create the simulations, documentation, and publications are freely available for download from the SimTK project site. The user community is also encouraged to make refinements and share them.

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'''Rule 8: Get independent reviews'''
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 Prior to making the model publically available, the model was submitted for independent review in conjunction with publication review of their manuscript. During the initial submission of the manuscript and model:

  * All four reviewers were able to reproduce the results reported in the manuscript;
  * Reviewers noted a need for more streamlined and documented process to re-run simulations; and
  * Several data discrepancies were identified in the initial submission of the manuscript and model [4].

 With resubmission of the manuscript and model, Rajagopal et al. made several enhancements that improved the usability of the model and alleviated data discrepancies. 

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'''Rule 9: Test competing implementations'''
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 * Simulation computation time of the model was compared to two other commonly used OpenSim models:  the Delp model modified to include arms, and the Arnold model (both cited in Rajagopal et al. [2])
 * Model’s fidelity to simulate normal gait was not compared with these two commonly used models or any other model. 

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'''Rule 10: Conform to standards'''
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 * Model testing conformed to published guidelines for best practices [[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4321112/|“Best practices for verification and validation of musculoskeletal models and simulations of human movement”]] [5] 
 * Human subject testing was carried out with Institutional Review Board approval
 * Data collection, processing, and reporting methods conformed to practices generally accepted by the biomechanics community.

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'''Review Details'''
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'''Information Sources'''

 [1] [[https://https://translational-medicine.biomedcentral.com/articles/10.1186/s12967-020-02540-4#MOESM1|Erdemir, A, et al. "Credible Practice of Modeling and Simulation in Healthcare: Ten Rules from a Multidisciplinary Perspective," Journal of Translational Medicine, 18:369, 2020.]]
 
 [2] [[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5507211/|Rajagopal A, Dembia CL, DeMers MS, Delp DD, Hicks JL, Delp SL.," Full-Body Musculoskeletal Model for Muscle-Driven Simulation of Human Gait," IEEE Trans Biomed Eng. 2016 Oct;63(10):2068-79. doi: 10.1109/TBME.2016.2586891. Epub 2016 Jul 7.]]
 
 [3] [[https://simtk.org/projects/full_body|Project website]]
 
 [4] [[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5225786/|Erdemir A, Guess TM, Halloran JP, Modenese L, Reinbolt JA, Thelen GD, Umberger BR., "Commentary on the Integration of Model Sharing and Reproducibility Analysis to Scholarly Publishing Workflow in Computational Biomechanics," IEEE Trans Biomed Eng. 2016 Oct;63(10):2080-2085. doi:10.1109/TBME.2016.2602760.]]

 [5] [[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4321112/|Hicks JL, Uchida TK, Seth A, Rajagopal A, Delp SL., "Is My Model Good Enough? Best Practices for Verification and Validation of Musculoskeletal Models and Simulations of Movement," J Biomech Eng. 2015 Feb 1;137(2):020905. doi: 10.1115/1.4029304.]]

'''Analysis History'''

 * Original review by Lealem Mulugeta on March 20, 2018
 * Updated by Joy Ku on April 23, 2020. Added categories for defining context (Rule 1).
 * Updated by Ahmet Erdemir on July 25, 2020. Added additional citations in regard to independent review (Rule 8) and conformance to standards (Rule 10).
 * Updated by Joy Ku on October 20, 2020 to match Ahmet Erdermir's edits for supplementary material for related publication [1]. 

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