Development and Testing of a Novel Stabilizer Clamp to Reduce Motion During Instrumented Cervical Fusions: The Caption System

BACKGROUND: Navigation of spinal instrumentation is heavily dependent on maintaining an accurate registration of the local anatomy to the navigation software. Any motion of the anatomy reduces accuracy. Historically, navigation in the cervical spine has been limited by the mobile nature of the anatomy. Here, we describe the development and testing of a novel stabilizer clamp designed to reduce motion and improve stability for navigated-instrumentation accuracy. METHODS: Testing was completed both on a flat-top table and separately on a Jackson table. On both tables, the cadaveric specimen was positioned prone with a Mayfield clamp. A total of 30 trials were completed as 3 repeats over 10 applications with force in the anteroposterior (AP) direction, and 30 additional trials with force in the medial-lateral (ML) direction. Displacement was recorded using a digital motion indicator for each trial. The experiment was then repeated after the addition application of a novel cranial stabilization system (Caption device). RESULTS: < 0.05 for each). The result was consistent when the cadaver was positioned both on the flat-top table (50.3% AP and 79.6% ML reduction) and on the Jackson table (53.5% AP and 92.5% ML reduction). With the device attached to the extended bed rails, the Caption cervical stabilization system reduced deflections by 45% AP and 69% ML when compared to deflections without the use of the stabilization system. CONCLUSIONS: The addition of a supplementary cranial stabilization system significantly reduces cranial motion compared with the use of only a Mayfield clamp. CLINICAL RELEVANCE: Increased stability of the cranial and cervical anatomy may allow for a reduction in malposition of navigated cervical instrumentation. Particular benefit may be seen in minimally invasive cases where the bony anatomy cannot be directly visualized, and in placement of cervical pedicle screws where the anatomic tolerances required are very high.