The clinical features of cevical spine pedicle screw malposition

English Keywords:Cervical pedicle screw  Misplacement  Complication  Feature

English Abstract:

  【Abstract】 Objectives: To evaluate the accuracy of cervical spine pedicle screw(CPS) insertion, and to explore the features of pedicle screw misplacement. Methods: Thirty-two patients stabilized by CPS were included. The cervical disorders included cervical fracture/dislocation(16 cases), ossification of posterior longitudinal ligament(8 cases), multiple cervical intervertebral disc herniation(1 case), neurilemoma(3 cases), spinal meningioma(3 cases) and ependymoma(1 case). Pre- and post-operative computed tomography(CT) scanning and multiple-planner reconstruction were used to determine the relevant parameters(entry point, the angle, the diameter and the length of pedicle) and accuracy of the CPS insertion. And the accuracy was classified according to Lee′s classification criterion: grade 0, no perforation; grade 1, perforation less than 25%; grade 2, perforation more than 25% but less than 50%; grade 3, perforation more than 50%. Grade 2 and 3 were regarded as misplacement. The pedicle screw placement was under the guidance of C-arm fluoroscopy. The features of screw misplacement were observed. Clinical outcome was assessed in all cases. Results: Among thirty-two patients, three lateral mass screws and one C1 laminar hook were used to replace preoperative planned pedicle screws. One hundred and forty-seven CPS were placed(40 screws in C1-C2, 107 screws in C3-C7), including 53 screws with grade 0, 67 screws with grade 1, 17 screws with grade 2(2 screws in C1-C2, 15 screws in C3-C7), and 10 screws with grade 3(1 screw in C1-C2, 9 screws in C3-C7). The total misplacement rate was 18.3%(grade 2 and 3, 27/147): 17 screws perforated lateral wall, 5 screws perforated inferior wall, 4 screws perforated superior wall, and 1 screw perforated medial wall. Pedicle screw perforation rate in C1-C2(7.5%, 3/40) was statistically less than that in C3-C7(22.4%, 24/107)(P<0.05). The rate of lateral wall perforation(11.5%) was statistically higher than that of superior wall(2.7%), inferior wall(3.4%) and medial wall(0.7%)(P<0.01), respectively. Bleeding from pedicle trajectory was found in 6 pedicles of 5 patients and was filled with bone-wax before pedicle screw insertion. Three patients complained postoperative radicular pain on the upper limb and relieved after restriction of cervical motion and neurotrophic medicine administration. No other complications were found. Conclusions: Misplacement of CPS occurs frequently, but relevant complications are scarce. Lateral wall perforation is more frequent than whtat of medial, superior or inferior wall. The incidence of pedicle screw perforation in C3-C7 is more than that in C1-C2.