Evaluation of the effect of vertebral and disc mechanical torsion on the correction achieved by posterior instrumentation in adolescent idiopathic scoliosis
KeywordsMagnetic Resonance Imaging Vertebral Body Adolescent Idiopathic Scoliosis Idiopathic Scoliosis Cobb Angle
To evaluate the effect of rotational deformation ('mechanical torsion') on the short-term and long-term effectiveness of modern posterior spinal instrumentation in treating the three-dimensional deformity of adolescent idiopathic scoliosis.
Ten patients with idiopathic scoliosis were imaged with three-dimensional magnetic resonance imaging pre-operatively and at six weeks and twelve months post-operatively following Isola posterior instrumentation . Changes in the three-dimensional deformity were measured, and the effect of mechanical torsion within the vertebral bodies and discs on the overall changes analysed.
Posterior instrumentation causes partial and temporary improvement in disc mechanical torsion but insignificant improvement in vertebral mechanical torsion. Changes in disc torsional deformity correlate with changes in apical rotation, Cobb angle and thoracic hypokyphosis.
Mechanical torsion within the vertebral bodies and discs of patients with idiopathic scoliosis presents a fundamental obstacle to effective derotational surgery, and is closely related to subsequent changes in the overall three-dimensional deformity following instrumentation.
This article is published under license to BioMed Central Ltd.