Recurrent Atlantoaxial Instability Due to Fracture of the Posterior C1 Ring: A Late Finding Following Posterior C1–C2 Fusion Using the Halifax Clamp

Although its use has fallen out of favor, the Halifax interlaminar clamp was used for many years to treat cervical instability through a posterior approach. Numerous complications, the majority of which are related to hardware failure, have been reported with the use of the interlaminar clamps and have led to the development of alternative techniques for posterior fusion, such as transarticular screw fixation. This report presents a case of recurrent atlantoaxial instability due to fracture of the posterior C1 ring that occurred 12 years after a posterior C1-C2 fusion with Halifax clamps. To the authors’ knowledge, this is the first case report of symmetric fractures through the posterior C1 ring lateral to the site of the Halifax clamps, resulting in recurrent atlantoaxial instability. This report focuses on the surgical management of this complication and provides a review of the literature that pertains to complications following the use of the Halifax clamp to treat atlantoaxial instability. (Journal of Surgical Orthopaedic Advances 18(1):45–50, 2009)