title: A model of the upper extremity for simulating musculoskeletal surgery and analyzing neuromuscular control.
abstract: Biomechanical models of the musculoskeletal system are frequently used to study neuromuscular control and simulate surgical procedures. To be broadly applicable, a model must be accessible to users, provide accurate representations of muscles and joints, and capture important interactions between joints. We have developed a model of the upper extremity that includes 15 degrees of freedom representing the shoulder, elbow, forearm, wrist, thumb, and index finger, and 50 muscle compartments crossing these joints. The kinematics of each joint and the force-generating parameters for each muscle were derived from experimental data. The model estimates the muscle-tendon lengths and moment arms for each of the muscles over a wide range of postures. Given a pattern of muscle activations, the model also estimates muscle forces and joint moments. The moment arms and maximum moment-generating capacity of each muscle group (e.g., elbow flexors) were compared to experimental data to assess the accuracy of the model. These comparisons showed that moment arms and joint moments estimated using the model captured important features of upper extremity geometry and mechanics. The model also revealed coupling between joints, such as increased passive finger flexion moment with wrist extension. The computer model is available to researchers at http://nmbl.stanford.edu.
authors.affiliation: Mechanical Engineering Department, Stanford University, Stanford, California 94305, USA.
authors.forename: Katherine R S
authors.initials: KR
authors.lastname: Holzbaur
authors.forename: Wendy M
authors.initials: WM
authors.lastname: Murray
authors.forename: Scott L
authors.initials: SL
authors.lastname: Delp
mesh_terms: D001696:Biomechanical Phenomena / Q000379:methods; D003198:Computer Simulation; D006801:Humans; D007537:Isometric Contraction; D007596:Joints / Q000502:physiology; D008953:Models, Anatomic; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D034941:Upper Extremity / Q000502:physiology* / Q000601:surgery