Modeling of the Cervical Spine as a System With Several Degrees of Freedom Subjected to a Non-periodic Excitation Force.

Background: and rationale: Previous cervical traction studies have investigated the impact of traction force intensity and duration of traction force on outcomes of cervical traction therapy. Objective The present study aims to demonstrate the impact of the intensity of the traction force and the time of the rise of this force on the measurement of separation during cervical spine traction. Method the human cervical spine was modeled as a system with eight degrees of freedom, an undamped system subjected, first of all, to a force of rectangular impulse then to a force of progressive intensity (sloping). The equations of motion describing this model were written and then solved using modal analysis. The intensity of the traction force and the time rise of the force were gradually modified in order to verify their impact on the evolution of the increase in intervertebral spaces. Result the numerical results showed that the intervertebral spaces calculated using different increments of the rise time (1'', 5'', 10'', 15'' and more) do not differ much and this remains proportional to the gradual increase in the tensile force applied (100N, 150N, 200N). A gradual increase in the intervertebral spaces has also been observed, these spaces being all the higher as the tensile force is greater. Conclusion This study confirms the need to monitor the speed of deployment of the traction force (rise time) as well as the progressive evolution of the widening of the intervertebral spaces, proportional to the traction force applied. However, it emphasizes that the time variation of the climb has almost no influence on the gain in intervertebral space. Hence the need on the one hand to monitor the speed of execution of the cervical traction to avoid damage to the anatomo- physiological structures and on the other hand the downward revision of the duration of a cervical traction session.