頚椎椎弓根スクリュー (CPS) 刺入精度の変遷

—ナビゲーションシステムを中心に—

抄録

  Objective : Cervical pedicle screw (CPS) may be the best anchor system for posterior cervical segmental fixation, but may carry high surgery-related risks such as neurovascular injury. The purpose of this study was to evaluate the accuracy of CPS placement by using various techniques such as a free-hand, computer navigation system.

  Methods : Posterior cervical instrumented fixation using a CPS was performed in 156 patients during the period January 2002 to April 2016. The patients were divided into five groups depending on the insertion techniques as follows : group 1 (free-hand technique with fluoroscopy), group 2 (preoperative three-dimensional [3-D] computed tomography [CT] based navigation system), group 3 (intraoperative 3-D CT based navigation system : O-arm), group4 (O-arm plus a cannulated screw), and group 5 (full-time navigation system).

  Results : At the spinal level of C2 through T3, 861 CPSs were placed. The radiological accuracy of the CPS placement was evaluated by using postoperative CT (post-insertion intraoperative CT when using an O-arm). The rate of-CPS misplacement (more than half of the screw) was 14.5% (8/55 screws) with the free-hand technique, 3.1% (14/452 screws) with the preoperative 3-D CT based navigation system, 1.1% (2/178 screws) with an O-arm, 0.8% (1/132 screws) with an O-arm plus a cannulated screw, and 0% with the full-time navigation system. In total, 54 screws (6.2%) were found to perforate the cortex of the pedicle, although no neural or vascular complications closely associated with CPS placement were observed.

  Conclusion : Image-guided CPS placement has been an important advancement to secure the safety of surgery, although whether a CPS is needed should be carefully determined on the basis of the individual pathology and background.