Technique of Pedicle Screw Fixation and Derotation for the Improvement of Rotational Deformity in Scoliosis Surgery:Derotation:Screw Rotation

Lee, Sang Min; Suk, Se Il; Kim, Jin Hyok; Kim, Won Joong; Jung, Ewy Ryong; Nah, Ki Ho; Sohn, Hong Moon; Lee, Sang Hoon

Abstract

STUDY DESIGN: This is a prospective design. SUMMARY AND BACKGROUND DATA: Derotation makes powerful coronal and satisfactory sagittal correction, however, making rotational correction is still controversy.
OBJECTIVES
To introduce a new technique to improve the vertebral rotation.
METHODS
1. Fix the pedicle screws of concave side of thoracic spine with nut driver or derotator before derotation maneuver. 2. During the derotation (counter-clockwise), rotate the nut driver/derotator to the opposite direction (clockwise).
RESULTS
A King type II AIS girl with the magnitude of right thoracic and left lumbar curve was 54 degrees and 40degress respectively was reviewed. Thoracic apical rotation was checked 32 degrees. When derotation maneuver was done, the Cobbs angle of thoracic verteba was corrected to 14 degrees (74.1%), however the apical angle was aggravated to 34 degrees . When derotation-screw rotation(DSR) was done, thoracic angle was corrected to 3 degrees with 94.4% of curve correction. The apical rotation was improved to 25 degrees. Preoperative 19.6 degrees of RAsac was corrected to 10.4 degrees showing 46.9% of correction. Postooperatively she was balanced inspite of overcorrection.
CONCLUSION
Derotation itself did not improve or slightly aggravate the rotation of apical vertebra. Apical rotation was dramatically improved by derotation combined by screw rotation technique. Maximal curve correction was obtained without trunk decompensation. This new technique may replace the advantages of anterior instrumentation in better rotational correction and saving fusion levels.