[Experimental study of laminectomy of the cervical spine]

The influence of laminectomy on the statics of the cervical spine was experimentally investigated. Pressure tests were carried out with isolated supravital cervical vertebrae with and without intact vertebral arches. Changes occurring during the pressure test were registered by stretching measurement strips. We tried to determine the relation between the height of laminectomy and the dorsal forces being necessary for the maintenance of lordosis in another series of experiments. The experiments were taken with a model developed by ourselves. Following results were reached: The vertebral arch is involved in the interception of axial forces. It shores up the back bird of the vertebral body. This is only visible with reaching the breaking load. A dorsal flexion wedge tilting over in the spinal canal breaks off at vertebrae without intact vertebral arch. After a laminectomy the lordosis of the cervical spine can only be kept up by the increase of dorsal forces. The necessary increase of forces is biggest with the laminectomy of the second and fifth vertebra. A motion-study shows that there occurs a buckling in the area of laminectomy during flexion.