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This project holds all the files necessary for a SIMM-based musculoskeletal model of the human lower-extremity which can also be easily imported and used in OpenSIM. 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.

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Please cite the following paper:
- Delp, S.L., Loan, J.P., Hoy, M.G., Zajac, F.E., Topp E.L., Rosen, J.M.: An interactive graphics-based model of the lower extremity to study orthopaedic surgical procedures, IEEE Transactions on Biomedical Engineering, vol. 37, pp. 757-767, 1990.

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About the model:
Originally developed in DATE by Scott Delp to examine how surgical changes in musculoskeletal geometry and muscle architecture affect muscle force and joint motion this model uses seven segments and seven degrees-of-freedom to represent the human lower extremity. The model is about 1.8m tall and has the strength of a young, adult male. Muscle lines of action for forty-three muscle-tendon actuators are based on their anatomical relationships to three-dimensional surface representations of bones. A model for each actuator was formulated to compute its isometric force-length relation. The kinematics of the lower extremity were specified by modeling the hip, knee, ankle, subtalar, and metatarsophalangeal joints. Thus, the force and joint moment that each muscle-tendon actuator develops can be computed for any body position. The joint moments calculated with the model compare well with experimentally measured isometric joint moments.

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