The project releases the ARMS Lab dynamic musculoskeletal model of the human hand and wrist, implemented in OpenSIM. Please see the model summary for details of the new model and its use. We include tutorials to perform simulations of maximal grip strength, maximal pinch strength, active hand opening, and passive hand opening with this model. In order to respect the time and effort put in by the original developers please carefully read accompanying publications and cite appropriate references in future work. The links to the left contain all the files (Downloads) and documentation (Documents) related to the model.

Please cite the following paper:
- The accompanying publication is currently under review for publication.
- A pre-print of the manuscript is available on biorxiv, citation information will be updated as the peer review process is completed.

In the meantime, please cite the biorxiv pre-print:
D. C. McFarland, B. I. Binder-Markey, J. A. Nichols, S. J. Wohlman, M. de Bruin, and W. M. Murray, "A Musculoskeletal Model of the Hand and Wrist Capable of Simulating Functional Tasks," bioRxiv, p. 2021.12.28.474357, 2021, doi: 10.1101/2021.12.28.474357.


About the model:
This model of the hand and wrist includes 23 independent degrees of freedom (DOF) including a flexion/extension DOF for each interphalangeal joint of the four fingers and thumb, flexion/extension and ab-adduction DOFs for each metacarpophalangeal joint of the fingers, a flexion/extension DOF for the metacarpophalangeal joint of the thumb, flexion/extension and ab-adduction DOFs for the carpometacarpal thumb joint, a coupled flexion DOF for the carpometacarpal joints of the ring and little finger, and flexion/extension and radial/ulnar deviation DOFs for the wrist. The model includes passive joint properties for all flexion/extension DOFs of the phalanges and thumb, for carpometacarpal ab-adduction of the thumb, and for wrist flexion and deviation DOFs. Forty-three Hill-type muscle-tendon actuators representing the intrinsic muscles of the hand, the extrinsic muscles of the hand, and the primary wrist muscles are included in the model. The kinematics of each joint and the force-generating parameters for each muscle were derived from experimental data. We include tutorials to perform simulations of maximal grip strength, maximal pinch strength, active hand opening, and passive hand opening. An optimal control theory framework that combines forward-dynamics simulations with a simulated-annealing optimization is used to simulate maximum grip and pinch force.

The model’s maximum grip force production match experimental measures of grip force, force distribution amongst the digits, and displays sensitivity to wrist flexion. Simulated lateral pinch strength falls within variability of in vivo palmar pinch strength data. The active and passive hand opening simulations predict reasonable activations and demonstrated passive motion mimicking tenodesis, respectively.