Direct transpedicular osteosynthesis with lag screw in the treatment for indicated Hangmans Fracture / 中华骨科杂志

ABSTRACT

Objective To define the indications of direct transpedicular lag screw to treat traumatic spondylolisthesis of axis (Hangmans fracure) and to evaluate the result of the technique. Methods From February 1998 to December 2000, 22 patients with acute traumatic spondylolisthesis of axis were treated. Ten of them achieved anatomic reduction by skull traction but no acceptable stability was ensured by traction alone. Among the ten patients, eight had integral and normal shaped C2 vertebral bodies (6 male, 2 female; age ranged from 18 to 42 years with an average of 28.2 years; 5, 2 and 1 patients classified as type Ⅰ, Ⅱ and Ⅱa injuries respectively according to Levine-Edwards classification and graded as D spinal injury in 2 cases and E in 6 cases according to Frankel scale) were further fixed with transpedicular lag screw. Under general anesthesia, the patients were laid in prostrate decubitus in a prepared head-neck-chest ventral plaster plate with skull traction in place to maintain reduction and lateral image intensification was applied to confirm the reduction. A posterior midline incision from C1-C3 was performed, and soft tissue was released to expose clearly the lamina, lateral mass, superior and medial aspect of the C2 pars interarticularis (isthmus plus pedicle). Points of entry for screw insertion were located at the entrance at the posterior aspect of lateral mass. The drill bit is parallel to both of the medial and superior border of C2 pars interarticularis (usually 25?-30? cephalad to the transverse plane and 30?-35? medial to the sagittal plane). The screw hole in the posterior cortex was overdrilled with a 3.5 mm drill bit for interfragmentary compression. 3.5 mm screws (25-30 mm, determined by depth gauge) were drived in after the cortex being tapped with a 3.5 mm tap. The whole procedure was done under monitoring of "C" arm fluoroscopy for safety and accuracy. Results It costs an average of 70 minutes to finish the procedure with mean blood loss of 250 ml. Hospital stay was about 18 days. A mean follow up time of 14 months (11 to 18 months) didnt confirm any early or late postoperative complications, all cases gained bony union 3 months later with complete neurological function recovery. The range of neck rotation was restored normal with no C2,3 instability or screw loosing found. Conclusion With appropriate indications, transpedicular lag screw fixation provides good reduction and stability to Hangmans fracture. This technique can only be applied to the fractures which are reductable.