Análise cinemática do deslocamento ao passo e das forças sobre as articulações do membro pélvico de bezerros durante o apoio

Abstract

The main purpose of this research is to obtain the internal forces on the joints, as well as the moments on the segments of young calves hind limbs obtained by inverse dynamic analysis of their gait during the stance phase. A biomechanical tow-dimensional model of the animals limb was developed and implemented in MATLAB to make this study possible. The input variables were obtained experimentally, with the kinematic and kinetic data collected through the technique of cinemetry and using the force plate provided by the Laboratório de Biomecânica do Esporte da Escola de Educação Física, Fisioterapia e Terapia Ocupacional (EEFFTO), of Universidade Federal de Minas Gerais (UFMG). For acquisition of inertial parameters (mass, center of mass and moment of inertia) of each segment, it was developed a methodology based on the construction of a simplified geometric model of a solid elliptical section from computerized tomography images produced at Veterinary Hospital of UFMG, with the purpose to obtain these parameters in vivo. The results of the simulation using solid elliptical section indicate that the model is a less expensive alternative and easy to calculate the inertial parameters of young calves, not requiring any equipment to obtain the results, showing relative error of up 10,9% to locate the center of mass, when compared to the values extracted by the computerized tomography, in which the original geometry of each segment is obtained from the segmentation of images and the density of each tissue is given to the obtained model. The results of dynamic analyses indicate that this technique is appropriated to evaluate the forces and the moments arising at the joints of the hind limb, as long as the values found match with the obtained results from studies of other quadrupeds (COLBORNE et al., 1998; CLAYTON et al., 2000, 2001; THORUP et al., 2007a; RODRIGUES, 2008). The magnitudes in the joint moments of the calves presented in this study were lower than those showed on horses and a little higher than those presented in pigs, being similar to the last one. The differences, however, can be attributed to the different methods of modeling and the segments size of each animal. From the presented methodology, it will be possible to perform analyzis of various situations, comparing the activities performed according different mechanical strategies and muscle of these animals.