Free-hand Pedicle Screw Placement in Adolescence Idiopathic Scoliosis

Pedicle screw instrumentation has many advantages for correction of adolescent idiopathic scoliosis (AIS) deformity, but screw insertion in AIS could be challenging due to distorted anatomy of pedicles and also rotation and tilt of the vertebrae. In “Free hand” technique, the surgeon locates the pedicle with anatomical landmarks. The purpose of this study was to evaluate the accuracy of pedicle screw position in correction of adolescent idiopathic scoliosis in “free hand” technique.
In a prospective study, 38 consecutive AIS cases who underwent corrective surgery with free-hand technique from 2013 to 2015 in a training hospital in Isfahan-Iran, were studied. Deformity corrections were evaluated with multislice CT-scan. In terms of position, pedicle screws were devided into “excellent” and “misplacement”. Misplaced pedicles were considered as medial, lateral, inferior, superior and anterior vertebral body and the dis-placement as grades 0 to 4.
A total of 720 screws were inserted. 623 screws (86.5%) were perfect and 97 (13.5%) were misplaced. In all the misplaced cases, 39 screws (40.2%) were medial and 58 (59.8%) were lateral and the deviation of screw was less than 2 mm (grade 1). There was no misplacement in the inferior or superior directions. Only one screw with 4 mm anterior misplacement associated with abdominal pain.
Pedicle screw insertion in adolescent idiopathic scoliosis with the “free hand” technique is a safe and reliable method with acceptable accuracy; if obviates time and radiation exposure.