ABSTRACT
STUDY DESIGN: The Perdriolle method was used to assess retrospectively radiographic pedicle rotation for association with occult intrathecal abnormalities in patients with scoliosis. OBJECTIVE: To determine if pedicle rotation can be predictive of underlying intrathecal abnormalities. SUMMARY OF BACKGROUND DATA: Scoliosis associated with intrathecal abnormalities is thought to produce less rotation than true idiopathic scoliosis. No supporting evidence was found in the literature. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.