[Surgical treatment of atlanto-axial dislocation. An introduction of two new methods]

In the past fourty-two months we have operatively treated twenty cases of several types of atlanto-axial dislocation (AAD) including an atlanto-axial deformity. A transoral retropharyngeal approach to the anterior arch of the atlas and the body of the axis was performed in two cases of AAD with dens fracture, 2 traumatic pure anterior AAD with relatively narrow spinal canal and 1 os odontoideum. The operative method we have devised is a modification of the transoral micro-surgical odontoid resection. In hyperextended position the fractured dens or os odontoideum comes to the position nearest to the anterior arch of the atlas and a distance between the atlas and the axis almost disappears. In this position a Halo device is installed and the anterior arch of the atlas, the dens and the body of the axis are fixed by an autograft all together. The articular joints between the atlas and the axis are also fixed by small grafts. The "three points fixation" of the atlanto-axial vertebrae may be a better and safer operative technique for selected AADs. Another method for AAD is a posterior atlanto-axial fixation using a metal plate (Urlich Medical Instruments Co., West Germany). This technique is a modification of fixation with wire and methyl methacrylate. A strong point of this new method is that the laminae of the atlas, axis and C3 vertebra in some cases, are fixed not with wire but a plate. The wire is used only to fix the plate on the laminae, so that the wire is not snapped on elastic fatigue.(ABSTRACT TRUNCATED AT 250 WORDS)