ABSTRACT
Introducción: La recuperación del grado de movilidad de las estructuras internas de la mano es un factor importante en la rehabilitación de pacientes. Objetivo: Estudiar la cinemática del movimiento de flexión-extensión de las estructuras internas del dedo pulgar a través de un mecanismo de palanca. Métodos: Se emplearon los métodos de análisis y síntesis de la teoría de mecanismos y máquinas. El dedo pulgar se definió como una cadena cinemática de tres grados de libertad. Resultados: La velocidad y aceleración máxima se obtuvieron en el recorrido de la posición extrema superior hasta la de agarre. La velocidad angular para la unión metacarpo-falángica (MCP) fue 9.12 rad/s, 18.10 rad/s en la inter-falángica proximal (PIP) y 10.07 rad/s en la inter-falángica distal (DIP); la velocidades lineal para la unión metacarpo-falángica (MCP) fue 0.45 m/s, 0.73 m/s en la inter-falángica proximal (PIP) y 0.30 m/s para la inter-falángica distal (DIP); as aceleraciones para MCP fue 4.10 m/s2 en el caso de la tangencial, 187.61 m/s2 para la normal; en la inter-falángica proximal (PIP) fue de 13.3 m/s2 en el caso de la tangencial, 163.71 m/s2 para la normal; y para la inter-falángica distal (DIP) fue de 3.04 m/s2 en el caso de la tangencial, 31.52 m/s2 para la normal. Conclusiones: Se definen las ecuaciones fundamentales que permitieron el obtener las velocidades y las aceleraciones durante el movimiento de flexo-extensión de las uniones del mecanismo, en las posiciones principales del dedo pulgar(AU)
Introduction: The recuperation of the range of mobility of the hand is an important factor in the patient rehabilitation. Objective: To study the kinematics of the flexion-extension movement of the thumb by a bar mechanism. Methods: The methods of analysis and synthesis of the theory of mechanisms and machines were used. The thumb was defined as a kinematic mechanism of three degrees of freedom. Results: The maximum speed was obtained between the upper position and the intermediate (or gripping) position. The angular velocities for the metacarpophalangeal joint (MCP) were 9.12 rad/s, in the proximal inter-phalangeal (PIP) of 18.10 rad/s and the distal inter-phalangeal (DIP) 10.07 rad/s. Also the linear velocities behaved as follows for the metacarpophalangeal joint (MCP) was 0.45 m/s, in the proximal inter-phalangeal (PIP) of 0.73 m/s to the distal inter-phalangeal (DIP) 0.30 m/s. Also the maximum accelerations are also obtained from the upper-end position to the intermediate (or gripping). Accelerations for the metacarpophalangeal joint (MCP) were 4.10 m/s2 for tangential component, 187.61 m/s2 for normal component; in the proximal phalangeal inter (PIP) was 13.3 m/s2 for tangential component, 163.71 m/s2 for normal component; and inter-phalangeal distal (DIP) were 3.04 m/s2 for tangential component, 31.52 m/s2 for normal component. Conclusions: The fundamental equations that allowed obtaining the velocities and accelerations during the movement of flexion and extension of the mechanism joints in the main positions of thumb were defined(AU)
Subject(s)
Humans , Thumb , Biomechanical Phenomena/physiology , Hand Injuries/rehabilitationABSTRACT
OBJECTIVES: 3D patient-specific model of the tibia is used to determine the torque needed to initialize the tibial torsion correction. METHODS: The finite elements method is used in the biomechanical modeling of tibia. The geometric model of the tibia is obtained from CT images. The tibia is modeled as an anisotropic material with non-homogeneous mechanical properties. CONCLUSIONS: The maximum stress is located in the shaft of tibia diaphysis. With both meshes are obtained similar results of stresses and displacements. For this patient-specific model, the torque must be greater than 30 Nm to initialize the correction of tibial torsion deformity.