Coronal alignment in normal individuals and moderate scoliosis: Normative values, variation with age and comparison with sagittal alignment.

Abstract

Introduction: Global coronal alignment is mainly assessed by C7 plumbline and central sacral vertical line (CSVL), pelvic obliquity and shoulder alignment. A detailed analysis is mandatory when treating spinal deformity. It remains unclear to what extent mild scoliosis influences global coronal alignment.

Research question: The objective was to define a comprehensive set of coronal alignment parameters and to investigate differences between individuals without spinal deformity and with mild scoliosis. The relationship between coronal and sagittal alignment and the influence of age were studied.

Methods: Radiographs of 236 normal individuals (Group N) and 140 patients with scoliosis <35° (Group S) were prospectively collected. Coronal parameters were femoral head distance and angle, pelvic obliquity, Maloney angle, L4 and L5 inclinations, coronal T1 pelvic angle, C7-CSVL and odontoid CSVL offset, coracoid distance and angle. Sagittal cervical, spinopelvic, thoracolumbar and global parameters were measured.

Results: There was no significant difference between groups N and S for coronal parameters, except for L4 and L5 inclinations with a mean difference of 3,3° (p < 0,001). Global coronal alignment kept constant throughout age groups in N and S groups. Sagittal parameters varied with age: C2-C7 lordosis (p < 0,001), T1-T12 kyphosis (p < 0,001), pelvic incidence (p < 0,001). There was no correlation between global coronal and sagittal alignment: R-values ranging from -0.2 to 0.2.

Conclusion: Global coronal parameters were comparable in normal individuals and in scoliosis <35°. Coronal plane parameters were not influenced by age. Sagittal plane parameters varied significantly with age. There was no direct link between coronal et sagittal alignment.