Since 1943, nine patients have had cervico-occipital fusion performed at the Mayo Clinic. Two patients had definite congenital anomalies, three had roentgenographic evidence of a separate odontoid process with dislocation of the atlas on the axis, and four had dislocation or instability as a result of severe trauma to the neck. In most cases the technique of Cone and Turner was used, with modifications. Fusion to the occiput and to the vertebrae resulted in six of the nine patients.
The study of these cases has led to the conclusion that many patients who have had a diagnosis of an ununited fracture of the odontoid with dislocation of the atlas on the axis actually have had a congenital anomaly of the odontoid and possibly a congenital anomaly of the associated ligaments. It also seems probable that patients in whom spontaneous dislocation of the atlas develops in comijunction with an infectious process may be more susceptible to such dislocation because of an underlying congenital or post-traumatic anomaly of the odontoid process and the neighboring ligaments.
Cervico-occipital fusion is successful in the majority of cases. It is more likely to result if extensive posterior decompression of the spinal cord is not necessary. However, if such decompression is not necessary, fusion of only the first and second cervical vertebrae is usually required. Prolonged immobilization of the head and cervical portion of the spinal column, preferably with a brace, until the wound is healed and then with either a Minerva or Calot type plaster-of-Paris cast followed again by the brace for a total of six to twelve months, is necessary for cervico-occipital fusion. The limitation of motion resulting from fusion of the occiput to the axis is hardly missed by the average person.