Pedicle rotation in scoliosis: a marker for occult intrathecal abnormalities

The Perdriolle method was used to assess retrospectively radiographic pedicle rotation for association with occult intrathecal abnormalities in patients with scoliosis.

To determine if pedicle rotation can be predictive of underlying intrathecal abnormalities.

Scoliosis associated with intrathecal abnormalities is thought to produce less rotation than true idiopathic scoliosis. No supporting evidence was found in the literature.

A consecutive series of patients with a presenting diagnosis of idiopathic scoliosis were reviewed for anteroposterior radiographs and spinal magnetic resonance imaging (MRI). A blinded single examiner evaluated radiographic curve parameters. MRI reports were reviewed for the presence or absence of intrathecal abnormalities.

A total of 78 MRIs included 15 intrathecal abnormalities and 63 normals. The abnormal MRI group had more males and apex left curves. Primary curve in the intrathecal abnormality group had a mean of 9.6 degrees of apical vertebrae rotation compared to 17.7 degrees in idiopathic curves (average 37 degrees and 40 degrees Cobb angles, respectively). Of angulation, 1 degrees correlated with 0.21 degrees and 0.34 degrees of rotation in intrathecal abnormality versus no abnormality groups, respectively.

Curves with occult intrathecal pathology had significantly less rotation than those without. Pedicle rotation assessment is a useful adjuvant for identifying scoliosis with intrathecal abnormalities.