The Research Of The Digital Image Method Of The Measurement About The Cervical Spine Movement In The Three-dimensional Space And The Mechanical Properties Of Cervical Spine

Three-dimensional human motion data measurement has a lot of applications in clinical rehabilitation, animation design and so on. In the field of clinical medicine, this technology is widely used in measuring the degrees of cervical spine. Cervical spine is the most complex structure of spine, its exercise frequency is highest, and it is the largest loading part of the body. Because the lifestyle of modern people has changed, cervical disease has become a common disease in the aged, the incidence rate is between 3.8% to 17.6%. As the number of patients with cervical vertebra disease is increasing year by year, the number of cervical spondylosis surgery is also increasing. The movement of each joint of the lower cervical spine is important for the diagnosis of the cervical spondylosis.According to the structural characteristics of the cervical spine, a 3-D spine motion measurement system has been build. Three marks are posted on the corresponding position of spinous process and transverse process of each cervical vertebrae. Using the technique of stereo vision and 3D digital image correlation(3D-DIC),four cameras are circularly arranged tracking the position of the marks without dead angle. Through the precision analysis, the precision of this system can reach 0.2mm. Then according to the cervical vertebra coordinate system,the angles of the cervical spine joints are computed, when the tester's cervical spine is moving, such as flexion, lateral bending and axial motions. In addition, the coupling relationship of the cervical spine joints can also be computed.Only using the digital image method, the measurement of the cervical spine movement has obvious defects. This system has been improved to solve these problems by proposing a parameter measurement method based on the relationship of the lower cervical spine motion. The angle is obtained by measuring the marker positions of each cervical joint during movement. Based on the method of measuring the instantaneous center of the motion and the regular pattern of the coupling motion, a kinematic model of the cervical spine is proposed in accordance with the kinematics characteristic of the lower cervical spine. According to the parametric model of the cervical spine, the motion curve is revised to improve the accuracy of measurement.Finally, we obtain the biomechanical parameters of cervical spine from the relevant medical literature, deep and detailed study the biomechanical property of cervical spine, reasonably simplify the cervical vertebrae, intervertebral disc and ligament and apply them in the mechanical model of the cervical vertebra. At last we analysis the cervical spine model using second types of Lagrange formula. By the calculation of the stress of intervertebral disc in different modes of motion, we can analysis the mechanical characteristics of the cervical intervertebral disc in the process of movement.