The contribution of an electronic conductivity device to the safety of pedicle screw insertion in scoliosis surgery

STUDY DESIGN.: Retrospective, controlled clinical study. OBJECTIVE.: To evaluate the contribution of an electronic conductivity device (ECD) to the safety of pedicle screw insertion in pediatric scoliosis surgery. SUMMARY OF BACKGROUND DATA.: The implantation of pedicle screws in spinal deformity correction surgery has evolved into the currently predominant fixation technique. Methodologies for optimizing placement of pedicle screws are fluoroscopy, electromyography, and intraoperative image-based navigation. A hand-held ECD was recently introduced. METHODS.: Pedicle screw insertion was analyzed in 248 pediatric scoliosis patients (idiopathic, congenital, neuromuscular, syndromatic). Group I included 150 procedures without the aid of the ECD and group II included 98 ECD-aided procedures. The two groups were matched by age, sex, etiology, Cobb angle, and surgical criteria. Data on screw position and concomitant neuromonitoring alarms were compared. Group I consisted of patients operated with both the hybrid construct and pedicle screw instrumentation, while group II consisted of patients operated solely with pedicle screws. Both groups were operated on by a single surgeon with the same neurophysiologic methodology. Clinically relevant misplaced pedicle screws were established by intraoperative monitoring alarms concomitant with pedicle screw insertion. RESULTS.: A total of 1270 pedicle screw placements were analyzed in group I and compared with 1400 pedicle screw placements in group II. Neuromonitoring alarms concomitant with screw placement occurred in 10 procedures in group I (6.6%) compared with 3 in group II (3.0%). The contribution of the electronic device to reducing the number of neurophysiologic alarms was significant (P = 0.048, Fisher exact test). Nine of the 13 monitoring alarms (69%) were associated with implantation adjacent to the apex of the spinal curve. CONCLUSION.: The use of an ECD significantly reduced the incidence of clinically relevant misplaced screws in a variety of scoliosis patients, thereby increasing the safety of pedicle screw implantation.