By way of three-dimensional measuremont,the kinematics of the cervical spine after partial discoidectomy was studied on 8 specimens of functional spinal units from dogs.Each specimen was subjected to partial discoidectomy,fixed on a frame and given proper load.Records of the 3-dimensional motions,before and after partial discoidectomy were compared carefully.The data demonstrated that the partial discectomy did bring about definite ill-effect on kinematics of the cervical spine.