C_(2,3) pedicle screw fixation for management of unstable Hangman fractures / 中华骨科杂志

ABSTRACT

Objective To introduce the method of C2,3 pedicle screw fixation for management of unstable Hangman fractures and evaluate the clinical effects.Methods From October 2001 to October 2005,26 cases with unstable Hangman fractures were treated using Axis and Vertex pedicle screw system.According to the classification system designed by Levine depending on the radiological manifestations of Hangman fractures,there were unstable fractures in 26 cases,who were subdivided into type Ⅱ in 11 cases,type ⅡA in 10 cases and type Ⅲ in 5 cases.There were 18 males and 8 females,aging from 21 to 56 years with an average of 38.5 years.According to Frankel scale,graded as spinal injury D in 6 cases and E in 20 cases.Points of entry for C2 screw insertion were located at the entrance at the posterior aspect of lateral mass.The drill bit was parallel to both of the medial and superior border of C2 pars interarticularis(usually 15?-25? cephalad to the transverse plane and 20?-25? medial to the sagittal plane).The screw hole in the posterior cortex was overdrilled.3.5-4.0 mm screws(26-30 mm,determined by depth gauge)were drived in after the cortex being tapped.The points of screw penetration for the C3 pedicles was slightly lateral to the center of the articular mass and close to the inferior margin of the inferior articular process of the cranially adjacent vertebra.The insertion angle of the pedicle screw was 35?-45? medial to the midline in the transverse plane.3.5-4.0 mm screws,determined by depth gauge were drived in after the cortex being tapped.The whole procedure was done under monitoring of "C"-arm fluoroscopy for safety and accuracy.Results All patients were followed up from 6 to 54 months,with the average of 29 months.There were no screw loosing and breakage,and no spinal cord and vertebral artery injury after surgery.3 screws were placed too close to the vertebral artery canal in C2 and 7 screws in C3,but without clinical consequences.There were 16 cases in excellent,7 good,3 fair according to Mayo(McGrory)scores.Conclusion C2,3 pedicle screw fixation is a effected method for management of unstable Hangman fractures,which proved its value as a method achieving solid bony fusion combined with low rate of complications.