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

backgroundNavigation 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.

methodsTesting 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).

resultsThe Caption cranial stabilizer significantly reduced both AP motion (45%-53% reduction) and ML motion (69%-92% reduction;

conclusionsThe 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. LEVEL OF EVIDENCE: 5: