[Classification of the adolescent idiopathic scoliosis and preoperative strategy]

The authors analysed 841 patients (83% girls and 17% boys) with adolescent idiopathic scoliosis. 678 patients (group I) were treated with the Harrington technique and 163 patients (group II) were treated using multisegmental instrumentation. Follow-up time in group I was on average 14.2 years, and 28 months in group II. Preoperative assessment of patients in group was based on clinical and radiological examination. Assessment of the spine was mainly based on coronal radiogram done in an upright position and lateral side-bending radiograms in a supine position. Traction and lateral X rays were rarely taken into account in this study. The fusion area was decided according to the end vertebrae of the structural curves. The caudal end of the fusion area was identified using Harrington's stable zone. The curves were classified in accordance with the SRS suggestions. Taking into account the apex of the curve, the deformations were classified into: cervico-thoracic, thoracic, thoraco-lumbar, lumbar and lumbo-sacral curves. In group II the triplanar (3D) character of the deformity was taken into account. In the coronal plane the upper and lower stable vertebra of the major structural curves were identified using the CSVL (Central Sacral Vertical Line) based on long films (70 cm x 110 cm) with and without traction. Lumbar curve was classified as mild, moderate, severe according to CSVL. In the axial plane vertebral rotation was assessed according to Nash and Moe method. A careful analysis of lateral radiograms in the upright standing position was performed. Lateral radiograms were performed also in maximal flexion and hyperextension of the spine to obtain a dynamic evaluation of the sagittal plane. Conoral radiograms with maximal rotation of the trunk to assess mobility of the caudad segments of the deformity. Classification of the scoliotic deformity based on its triplanar character included: thoracic curves (King III, IV, V types), double major (thoracic and lumbar), "false" double major curve (thoracic and lumbar) King type II, thoracolumbar/lumbar curves--the main curve is thoracolumbar lumbar/thoracolumbar curves--the main curve is lumbar--10 degrees the thoracolumbar component--King type I triple major curve--all curves have similar structural changes. Correct identification of the type of scoliosis, assessment of structural changes in the frontal, sagittal and axial plane (three dimensional 3D) and analysis of the size and correctiveness of the lumbar curve and all parameters which play a key role in rational preoperative planning. Redefining or at least maintaining lumbar lordosis is far more important than correction of thoracic kyphosis.