Intraoperative comparison of two instrumentation techniques for the correction of adolescent idiopathic scoliosis - Rod rotation and translation

Study Design. A prospective and controlled comparative study of two instrum entation techniques used :or the correction of adolescent idiopathic scolio sis. Objective. To measure the three-dimensional intraoperative correction obtai ned with a rotation maneuver as compared with that obtained with a translat ion maneuver of the first instrumentation rod inserted to determine the dif ference, if any, in the two techniques for achieving three-dimensional corr ection. Summary of Background Data. Adequate three-dimensional correction of scolio tic deformities has been reported with the Cotrel-Dubousset instrumentation using the rod-rotation maneuver. More recently, however, authors of studie s with newer instrumentation systems have claimed that better correction ca n be obtained using a translation technique. So far, no report has clearly demonstrated the three-dimensional changes obtained with this more recent i nstrumentation technique. Methods, The changes in position of thoracic and lumbar vertebrae exposed d uring surgery were documented using a three-dimensional magnetic digitizer in 70 adolescents with idiopathic scoliosis undergoing correction by a post erior approach. Vertebral positions were measured intraoperatively before a nd after the surgical maneuver in 39 patients with the Cotrel-Dubousset ins trumentation (rod rotation) and in 31 patients with the Colorado instrument ation (translation). Results. In both groups, adequate three-dimensional correction of the scoli otic deformities was documented, with significant chanties in the frontal a nd sagittal planes and in the orientation of the plane of maximum deformity for thoracic and lumbar curves. On the other hand, no significant differen ces were documented between the two procedures except in the frontal plane where a tendency for greater correction was observed for thoracic curves wi th the translation technique. Conclusions. The two instrumentation techniques are equally able to achieve a comparable and effective three-dimensional correction of the scoliotic d eformities. The use of either a rotation maneuver or a translation techniqu e during surgery does not result in any significant measurable difference i n three-dimensional correction.