Abstract
Objective: Idiopathic scoliosis is a complex, three-dimensional deformity. Surgical correction has been assessed by radiographic measurements in the coronal and sagittal planes and vertebral rotation. However the primary concern for the patient is the transverse plane deformity at the skin surface. The purpose of this study was to correlate the surface and radiographic measurements of transverse plane deformity in idiopathic thoracolumbar scoliosis before and after single stage anterior fusion with instrumentation.
Design: A consecutive, prospective study of patients operated upon by a single surgeon.
Subjects: 24 patients (23 female) with idiopathic thoracolumbar scoliosis operated on between 1990 and 1999. Mean age at surgery 14.8 yrs (range 10.9 to 17.5). All had single stage surgery through an anterior thoraco-abdominal approach with anterior release of a mean of 4 discs (range 3 to 6). Anterior instrumentation was inserted using vertebral body screws secured to a single contoured rod with interbody bone grafting using strips of rib autograft.
Outcome measures: All patients were assessed both radiographically and by surface topography using the Integrated Shape Imaging System (ISIS) pre-operatively, post-operatively and during each follow-up visit for a mean 3.1 years (range 1.8–9.1).
Results: Radiographically the mean pre-operative coronal Cobb angle of 49 degrees (range 30 to 74) was reduced to 13 degrees (range 0 to 32) following surgery with a mean 2 degree loss (range −5 to 10) at final follow-up. The Perdriolle rotation was reduced by a mean of 19 degrees (range 5 to 30) with a mean 1 degree loss (range −6 to 6) of correction at final follow-up.
ISIS showed the mean pre-operative Standing Angle of Trunk Inclination (sATI) of 15 degrees (range 7 to 25) was reduced to 5 degrees (range 0 to 15) post-operatively with a further mean improvement of 2 degrees during the follow-up period. The final sATI was within the range of normality for 21 patients (87 percent). Spinal balance in the coronal plane improved from a mean of 24mm to 11mm. Spinal balance in the sagittal plane was unchanged.
Conclusions: Anterior surgery for idiopathic thoracolumbar scoliosis is effective in reducing transverse plane deformity. The Standing Angle of Trunk Inclination is returned to the normal range in 87% of cases. Coronal plane balance is improved by surgery. These corrections occur mainly due to surgery but also continue on follow up (growth).
The abstracts were prepared by Mr Peter Millner. Correspondence should be addressed to Peter Millner, Consultant Spinal Surgeon, Orthopaedic Surgery, Chancellor Wing, Ward 28 Office Suite, St James’ University Hospital, Beckett Street, Leeds LS9 7TF.
