Screw fixation of the upper cervical spine in the pediatric population
Authors: Haque Atif , Price Angela V. , Sklar Frederick H. , Swift Dale M. , Weprin Bradley E. , Sacco David J. 
Published: September 2009

Object
Rigid fixation of the upper cervical spine has become an established method of durable stabilization for a variety of craniocervical pathological entities in children. In children, specifically, the use of C1–2 transarticular screws has been proposed in recent literature to be the gold standard configuration for pathology involving these levels. The authors reviewed the use of rigid fixation techniques alternative to C1–2 transarticular screws in children. Factors evaluated included ease of placement, complications, and postoperative stability.

Methods
Seventeen patients, ranging in age from 3 to 17 years (mean 9.6 years), underwent screw fixation involving the atlas or axis for a multitude of pathologies, including os odontoideum, Down syndrome, congenital instability, iatrogenic instability, or posttraumatic instability. All patients had preoperative instability of the occipitocervical or atlantoaxial spine demonstrated on dynamic lateral cervical spine radiographs. All patients also underwent preoperative CT scanning and MR imaging to evaluate the anatomical feasibility of the selected hardware placement. Thirteen patients underwent C1–2 fusion, and 4 underwent occipitocervical fusion, all incorporating C-1 lateral mass screws, C-2 pars screws, and/or C-2 laminar screws within their constructs. Patients who underwent occipitocervical fusion had no instrumentation placed at C-1. One patient's construct included sublaminar wiring at C-2. All patients received autograft onlay either from from rib (in 15 patients), split-thickness skull (1 patient), or local bone harvested within the operative field (1 patient). Nine patients' constructs were supplemented with recombinant human bone morphogenetic protein at the discretion of the attending physician. Eight patients had surgical sacrifice of 1 or both C-2 nerve roots to better facilitate visualization of the C-1 lateral mass. One patient was placed in halo-vest orthosis postoperatively, while the rest were maintained in rigid collars.

Results
All 17 patients underwent immediate postoperative CT scanning to evaluate hardware placement. Follow-up was achieved in 16 cases, ranging from 2 to 39 months (mean 14 months), and repeated dynamic lateral cervical spine radiography was performed in these patients at the end of their follow-up period. Some, but not all patients, also underwent delayed postoperative CT scans, which were done at the discretion of the treating attending physician. No neurovascular injuries were encountered, no hardware revisions were required, and no infections were seen. No postoperative pain was seen in patients who underwent C-2 nerve root sacrifice. Stability was achieved in all patients postoperatively. In all patients who underwent delayed postoperative CT scanning, the presence of bridging bone was shown spanning the fused levels.

Conclusions
Screw fixation of the atlas using lateral mass screws, in conjunction with C-2 root sacrifice in selected cases, and of the axis using pars or laminar screws is a safe method for achieving rigid fixation of the upper cervical spine in the pediatric population.