Authors: XinLiang Zhang DaGeng Huang XiaoDong Wang JinWen Zhu YiBing Li BaoRong He DingJun Hao
Publish Date: 2016/05/31
Volume: 26, Issue: 4, Pages: 1058-1063
Abstract
Ponticulus posticus is a common anatomic variation that can be mistaken for a broad posterior arch during C1 pedicle screw placement When the atlas lateral mass screws are placed via the posterior arch injury to the vertebral artery may result To our knowledge there are few clinical studies that have analyzed the feasibility of C1 pedicle screw fixation in patients with ponticulus posticus in clinical practiceBetween January 2008 and January 2012 11 consecutive patients with atlantoaxial instability and with a ponticulus posticus at C1 underwent posterior fusion surgery in our institution According to preoperative computed tomography CT reconstruction a complete ponticulus posticus was found unilaterally in nine patients and bilaterally in two Postoperative CT reconstructive imaging was performed to assess whether C1 pedicle screw placement was successful Patients were followed up at regular intervals and evaluated for symptoms of ponticulus posticus syndromeThirteen C1 pedicles atlas vertebral artery groove each with a complete ponticulus posticus were successfully inserted with thirteen 35 or 40mm diameter pedicle screws without resection of the bony anomaly No intraoperative complications venous plexus vertebral artery or spinal cord injury occurred The mean followup period was 21 range 14–30 months Postoperative CT reconstructive images showed that all 13 pedicle screws were inserted in the C1 pedicles without destruction of the atlas pedicle cortical bone In the followup period none of the patients demonstrated clinical symptoms of ponticulus posticus syndrome or developed bone fusionThreedimensional CT imaging should be considered prior to C1 pedicle screw fixation in patients with ponticulus posticus to avoid mistaking the ponticulus posticus for a widened dorsal arch of the atlas If there is no ponticulus posticus syndrome preoperatively C1 pedicle screw fixation can be successfully performed without removing the bony anomaly
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