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Two axes of rotation of the carpometacarpal (CMC) joint of seven cadaver thumbs were located using an axis finder. The flexion-extension axis is located in the trapezium and the abduction-adduction axis is in the first metacarpal. These axes are fixed, are not perpendicular to each other or to the bones, and do not intersect. Motion of the first metacarpal(More)
Most researchers have modelled the thumb as three rigid links with connections of two universal joints (carpometacarpal joint and metacarpo-phalangeal joint), and a hinge joint (interphalangeal joint). Although this produces the required number of degrees of freedom, the resulting motion is not anatomically accurate. In this work, the thumb is modelled as a(More)
The purpose of this work is to develop a 3D inverse dynamic model of the human finger for estimating the muscular forces involved during free finger movements. A review of the existing 3D models of the fingers is presented, and an alternative one is proposed. The validity of the model has been proved by means of two simulations: free flexion-extension(More)
The ideal diameter for a tool handle for males and females has been determined using an existing biomechanical model of the hand validated in previous works. The model estimates a 33-mm optimum diameter tool handle for the general population (males and females). When the optimum diameter for a tool handle is selected, the muscles exert the minimum force(More)
The axes of rotation of the thumb interphalangeal and metacarpophalangeal joints were located using a mechanical method. The interphalangeal joint axis is parallel to the flexion crease of the joint and is not perpendicular to the phalanx. This offset of the axis with respect to the phalanx explains the ulnar deviation and pronation that occurs with flexion(More)
A three-dimensional scalable biomechanical model of the four fingers of the hand to evaluate power grip is proposed. The model has been validated by means of reproducing an experiment in which the subjects exerted the maximal voluntary grasping force over cylinders of different diameters. The model is used to simulate the cylinder grip for two hand sizes(More)
A method for scaling the muscle action is proposed and used to achieve a 3D inverse dynamic model of the human finger with all its components scalable. This method is based on scaling the physiological cross-sectional area (PCSA) in a Hill muscle model. Different anthropometric parameters and maximal grip force data have been measured and their correlations(More)
Interactive graphics for hand surgery was used to apply mathematical modeling and describe the kinematics of the hand and its resultant effect on hand function. Dynamic high resolution displays and three-dimensional images were tailored for use with a specific patients' hand and a new and powerful design and analysis tool produced. Methods were developed to(More)
The multi-joint model is a kinematic simulation of the long flexor tendons of the fingers. The tendons modeled are the flexor pollicis longus, the flexor digitorum profundus, and the flexor digitorum superficialis. The simulated tendons are displayed on an Evans and Sutherland PS330 color graphics terminal attached to a display of articulated bones of the(More)
The clinical reliability of torque range of motion (TROM) has not been tested. This preliminary review was performed to determine the intra- and interrater reliability of TROM. The proximal interphalangeal joints of the index and middle fingers of 14 normal subjects, 56 digits, were tested by applying extension forces of 200 g, 400 g, 600 g, and 800 g. Data(More)