Over the past twenty years, there has been a significant increase in the use of cervical plates for single and multi-level anterior cervical surgery. For example, at the most recent Cervical Spine Research Society meeting, the members of this society reported using cervical plates in approximately 92% of all anterior cervical discectomies and fusions. One of the goals of a cervical plate is to improve initial stability in the post-operative period in order to decrease the need for wearing a cervical collar and result in a faster return to normal activities. In addition, anterior cervical plate fixation can potentially decrease the complications of graft dislocation, end plate fracture, and late kyphotic collapse.

The design team for the ATLANTIS™ Anterior Cervical Plate System, which includes the world-renowned spine surgeons Dr. Volker Sonntag, Dr. Regis Haid, and Dr. Stephen Papadopoulos, set out to create a comprehensive instrumentation system that would incorporate all of the ideal features of modern cervical plates in a single system. The features that are available in the ATLANTIS™ System include flexibility in construct choice, an attached locking mechanism, and variability in screw placement.

The ability to choose between unicortical and/or bicortical screw purchase allows the surgeon to tailor the amount of screw to cortex fixation to the needs of the patient. In primary cases with appropriate bone quality, a unicortical screw can be selected for ease of fixation without having to penetrate the distal (far) cortex. In revision surgeries, or situations where osteoporosis makes single cortex fixation less desirable, surgeons have the flexibility of using a bicortical screw for additional pull-out resistance.

Basics and Benefits
Anterior plate fixation offers many benefits such as: resistance to graft displacement, a reduced incidence of pseudoarthrosis (a type of non-union) related to micromotion, maintaining anterior cervical alignment when multi-level discectomies or corpectomies are performed, and a decreased need for bracing.

There are certain situations in anterior cervical surgery where the pre-determined trajectory of the fixed angle screw may be undesirable. The ATLANTIS™ Anterior Cervical Plate System can easily address these situations by allowing the surgeon to switch to a variable angle screw that permits greater freedom in choosing the placement and trajectory of the screw into the vertebral body. This need often arises in revision surgeries where screw purchase may be compromised by existing screw holes and more flexibility is needed in order to place a screw into solid bone.

Another common situation that may require the use of a variable angle screw arises when a hemi-corpectomy is performed in order to treat the underlying pathology. After the hemi-corpectomy has been completed, the amount of bone available for screw purchase can be quite small and a fixed angle screw with a 12 degree cephalad/caudal screw trajectory with respect to the plate may violate the disc space above or below the level of the surgery. In this instance, the variable angle screw allows the surgeon to chose a trajectory that is less steep and ensures that the screw is appropriately placed in the remainder of the vertebral body.

The third situation that often dictates the use of variable angle screws involves the placement of screws into vertebral bodies at the extremes of the cervical spine. Limited exposure of the inferior and superior (top and bottom) of the cervical spine can make fixed angle screw placement difficult because the proper positioning of the instrumentation may be impaired by soft tissue and the physiologic limits to further retraction. The variable angle screws permit a steeper trajectory so that the surgeon is able to place a screw into the vertebral bodies at either end of the cervical spine without having to adhere to the requirement for a 12-degree cephalad/caudad trajectory with the fixed screws.