Abstract:

Objective　To explore the characters of intra-stress distribution in cervical spine during cervical rotatory manipulation (CRM).　Methods　A 3D finite element model of C3/4～C6/7 was set up through software systems handling normal C3～C7 CT images. The decomposed mechanic parameters of CRM were analyzed by the finite element system. The changes of intra-stress distribution in model were displayed simultaneously during simulating manipulation.　Results　The size and region of stress suffered cervical model gradually decreased, and then increased gradually during pulling manipulation. The regions of stress concentration were mainly in C3/4 zygapophyseak joints. With increased thrust in C4 spinous process turning to the left, left bottom and root of C4 spinous process, combination area in left bottom and vertebral of pedicle C4 spinous process appeared stress concentration in turn, with the greatest stress of 9.627 kpa. In the process of cervical spine turning and right rotating about 40°, bilateral C3~C6 zygapophyseak joints, C4~C6 vertebral arch, the root of C4~C6 spinous process and the lateral side of C4~C6 vertebral body appeared stress concentration in turn, with the greatest stress of 363.6kpa in right of C3/4  zygapophyseak joints. The size and the region of stress suffered model reduced quickly at the stage of quickly returning to neutral position.　Conclusions　Cervical spine has its unique characters of intra-stress distribution under the CRM. Zygapophyseak joints suffer the major stress during the cervical spine movement.Model suffered the greatest stress under right rotation with 40°, but it did not injure the normal structrue of cervical spine.

Key words: Cervical spine, Finite element, Cervical rotatory manipulation, Stress