Rotational changes of the vertebral pelvic axis after sublaminar instrumentation in adolescent idiopathic scoliosis.
METHODS
The authors studied the rotational effect of sublaminar wiring on the spinal pelvic axis on 20 patients who were being treated for adolescent idiopathic scoliosis.


OBJECTIVE
To determine if sublaminar wiring effectively derotates the scoliotic spine.


BACKGROUND
The correction of the rotational deformity in adolescent scoliosis via sublaminar wiring is not well quantified in the literature. The derotation maneuver of Cotrel-Dubousset has been shown to produce variable and unpredictable amounts of axial derotation.


METHODS
Twenty patients who underwent posterior spine fusion for adolescent idiopathic scoliosis were evaluated using computed tomography scans and plain radiography before and after surgery and at a subsequent follow-up examination (average time of follow-up examination, 35 months after surgery). The degree of angle of vertebral rotation about the sagittal plane and that relative to the pelvis were measured before and after surgery and at a follow-up examination.


RESULTS
The primary thoracic curves were not derotated significantly relative to the pelvis with sublaminar wiring. Primary thoracolumbar curves instrumented on the convexity with pedicle screws were derotated significantly relative to the pelvis (P = .001). The average initial correction was 57%. On final follow-up examination, the correction was 24% (18 of 20 twenty individuals lost axial correction by an average of 34%). In nine of 20 patients the spine was more rotated, relative to the pelvis, than it had been before surgery. No coronal or sagittal decompensation was seen in any curve type.


CONCLUSIONS
Coronal and sagittal plane correction of scoliotic curves may be achieved with sublaminar instrumentation. The ability to derotate axially the scoliotic spine appears to be variable, however, and, in most cases, curve-type dependent. Over time, much correction appears to be lost, and in many patients the scoliosis actually becomes worse than it was before surgery. Nonetheless, the apical derotation that takes place appears to be reasonably true: the percent correction of angle of rotation about the sagittal plane and the percent correction of angle of rotation about the sagittal plain relative to the pelvis were closely correlated. Derotation forces applied to the instrumented spine do not appear to be transmitted to more distal segments.
Wood
K B
KB
Montefiore Medical Center, Bronx, New York, USA.
Olsewski
J M
JM
Schendel
M J
MJ
Boachie-Adjei
O
O
Gupta
M
M
D000293:Adolescent; D000328:Adult; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D009984:Orthopedic Fixation Devices; D010384:Pelvic Bones / Q000503:physiopathology*; D011184:Postoperative Period; D012399:Rotation; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery*; D013131:Spine / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome