Occipito-cervical fusion. Indications, technique and results.

Fusion ofthe occiput to the upper cervical spine is an uncommon but important operation as it is the only means ofpermanently stabilising the interveningjoints. Instability ofthe atlas or axis on the remainder of the cervical spine is dangerous, and if it progresses to subluxation or dislocation there is a risk of damage to the medulla, spinal cord and nerve roots. Fusion may be required for primary conditions causing instability in this region, such as congenital anomalies, spontaneous atlanto-axial dislocation, or post-traumatic dislocation following fracture of the dens [odontoid process]. It may also be necessary as a means of restoring stability after extensive cervical decompression by laminectomy. Occipito-cervical fusion was reported by Foerster (1927), who used a fibular graft to stabilise a progressive atlanto-axial dislocation after fracture of the dens. Juvara and Dimitriu (1928) attempted to fuse an unstable atlanto-axial dislocation with a tibial graft in a patient with tetraplegia: this patient died. The first reported operation using an iliac bone graft was that of Kahn and Yglesias (1935) in a case of progressive atlanto-axial subluxation after failed