Posterior rod system of the cervical spine: a new implant allowing optimal screw insertion.

A new implant system for posterior stabilisation of the occipitocervical junction and the cervical and upper thoracic spine is described. The system consists of rods and clamps. For fixation to the occiput, the 3.5-mm titanium rod goes over into a 3.5-mm AO-reconstruction plate. Several clamps may be fixed to the rod at variable intervals, depending on the anatomical situation and the specific needs. Five types of clamps with different angulations of the screw hole with respect to the rod allow optimal screw insertion and fixation of the rod at all levels instrumented. Locking screws may be used to allow fixed stabilisation of the screw to the rod. Hooks for sublaminar anchoring, connectors to other rods and a cross-linking device are also available. Unlike plate fixators, the system allows screw insertion at any angle and at any interval. Therefore, optimal screw insertion is possible in any anatomical situation. Furthermore, ample space is available for bone grafting of the posterior aspect of the lateral masses. This is especially important following a laminectomy. Preliminary clinical results in 20 patients are presented; no complications have been seen to date. Our system has recently been approved as an AO-implant.