Au Experimental And Biomechanical Study Of Anterior Distraction Between Cervical Vertebrae

Objective: To establish the optimal height of the strut-graft for clinical surgery, this study analyzed the effect of change in strut-graft height on the lordotic curvatures and immediate biomechanical stability of the cervical spine on which corpectomy and strut-graft reconstruction with different height was performed. Methods: Six fresh human cervical spine specimen of young cadaver were used for biomechanical test in following seven serial conditions: harvested, C5 corpectomy and strut-grafted respectively with a distraction of 0mm, 2mm, 4mm, 6mm and 8mm between C4 and C6 vertebra, C5 corpectomy and strut-grafted with an anterior cervical plate. For every work conditions , specimen were screened and made plain lateral radiographs to correlate strut-graft height with lordotic curvatures of cervical spine. Then six pure moments of 2.0 Nm were applied in flexion, extension , bilateral bending , bilateral axial rotation, parameters of three-dimensional motion were determined by sterophtography . After the radiographs been digitized, the angles between the posterior margins of vertebrae were measured by the computer image analysis software, and the immediate stability of C3,C5,C5,C4 compound and C6q in different conditions also was analysis by the computer. Results: Compared to the intact condition or strut-grafted without a distraction, the cervical spine lordotic curvatures of the C2-.q and C segments and the global immediate stability of the operated segments were significantly increased by the application of strut-graft with a distraction over 4mm. More significant decrease were foud in the rangs of extension, lateral bending and axial rotation movements. Conclusions: Strut-graft with an appropriate distraction after corpectomy plays an important role not only in regain and maintain the cervical spine lordotic curvatures but also in acquire the global immediate stability of the cervical spine. After single vertebra corpectomy, the proper range of distraction between the superior and inferior vertebra maybe among 4-6 millimeters.