Accuracy of thoracic pedicle screw placement using freehand technique and triggered EMG in adolescent idiopathic scoliosis: Is it different between concave and convex side?

Abstract

To evaluate and compare the accuracy of the placement of thoracic pedicle screws between concave and convex side curve using freehand technique and triggered electromyogram (EMG). Three-hundred sixty eight thoracic pedicle screws were included for the evaluation of accuracy from postoperative computed tomography (CT) scans in 24 patients with adolescent idiopathic scoliosis with a mean follow-up of 27 months (range 24-58 months). All screws had stimulation thresholds greater than 6 mA. We divided the screws into two groups: (1) group A: concave side curve-254 screws (2) group B: convex side curve-114 screws. The mean age at surgery was 12.8 years (range 11-17 years). The preoperative Cobb angle was 57.5° (range 50-75°). There were 41 total breaches (medial = 21, lateral = 20, p = 0.66) with an overall incidence of 11.1%. The overall breach rate did not attain statistically significant difference (group A = 11.8%, group B = 9.6%, p = 0.59). The rate of medial breaches was also similar for both concave and convex side (group A = 6.1%, group B = 5.9%, p > 0.05). No postoperative neurological or vascular complications were noted in both groups. Thoracic pedicle screw placement using both freehand technique and triggered EMG for adolescent idiopathic scoliosis surgery is safe and reliable. The overall accuracy rate is 88.9% with similar breaches on the concave and convex side on postoperative CT scans.