Surgical correction of scoliosis by in situ contouring: a detorsion analysis.

Methods: A detorsion analysis of the scoliosis surgical correction by means of in situ contouring technique (ISC). Objective: To describe the technique of ISC. To measure the vertebral and intervertebral axial rotation in thoracic and lumbar curves and their correction obtained by ISC.

Background: The vertebral and intervertebral axial rotation allows to evaluate the severity of the curves. However, the intervertebral axial rotation is barely studied and the vertebral axial rotation is a controversial point of the surgical correction.

Methods: Twenty patients with thoracic and lumbar scoliosis were operated on with ISC. Vertebral axial rotation at the apex and the sum of intervertebral axial rotations all along the curve were computed before and after surgery from the three-dimensional stereoradiographic reconstruction of the spine and the pelvis. All the measurements were made in the standing position.

Results: Correction of the axial rotation was obtained at the apex of both thoracic and lumbar curves of idiopathic and degenerative scoliosis. The mean values of correction (in terms of axial rotation) were 8 degrees to 19 degrees (62%-67%). The percentage of correction of the sum of intervertebral axial rotations all along the curve, proposed as a "detorsion index" (preoperative - postoperative/preoperative), was found at 57% to 92%. No significant differences were found for the correction (in terms of axial rotation and detorsion) between idiopathic and degenerative curves.

Conclusions: The axial rotation was measured in clinics on standing patients with scoliosis from three-dimensional stereoradiographic reconstruction and demonstrated a reliable detorsion obtained by ISC.