Is the apical vertebra the most rotated vertebra in the scoliotic curve?

Abstract

<jats:sec><jats:title>OBJECTIVE</jats:title><jats:p>The aim of this study was to determine if the apical vertebra (AV) in patients with adolescent idiopathic scoliosis (AIS) is the most rotated vertebra in the scoliotic segment.</jats:p></jats:sec><jats:sec><jats:title>METHODS</jats:title><jats:p>A total of 158 patients with AIS (Cobb angle range 20°–101°) underwent biplanar radiography with 3D reconstructions of the spine and calculation of vertebral axial rotations. The type of major curvature was recorded (thoracic, thoracolumbar, or lumbar), and both major and minor curvatures were included. The difference of levels (DL) between the level of maximal vertebral rotation (LMVR) and the AV was calculated as follows: DL = 0 if LMVR and AV were the same, DL = 1 if LMVR was directly above or below the AV, and DL = 2 if LMVR was separated by 1 vertebra or more from the AV. To investigate which factors explained the divergence of the LMVR from the AV, multinomial models were computed.</jats:p></jats:sec><jats:sec><jats:title>RESULTS</jats:title><jats:p>The distribution of the DL was as follows: for major curvatures, 143 were DL = 0, 11 were DL = 1, and 4 were DL = 2; and for minor curvatures, 53 were DL = 0, 9 were DL = 1, and 31 were DL = 2. The determinants of a DL = 2 (compared with DL = 0) were lumbar curvature (compared with thoracic; adjusted OR 0.094, p = 0.001), major curvature (compared with minor; adjusted OR 0.116, p = 0.001), and curvatures with increasing apical vertebral rotation (adjusted OR 0.788, p &lt; 0.001).</jats:p></jats:sec><jats:sec><jats:title>CONCLUSIONS</jats:title><jats:p>This study showed that the AV is the most rotated vertebra in the majority of major curvatures, while in minor curvatures, the most rotated vertebra appears to be the junctional vertebra between major and minor curvatures in a significant proportion of cases.</jats:p></jats:sec>

Maximal Axial Vertebral Rotation in Adolescent Idiopathic Scoliosis: Is the Apical Vertebra the Most Rotated?

“…Almost 54% of individuals (182 of 332) had maximal rotation in the vertebra adjacent to the apical vertebrum, and at a distance of 2 levels vertebra in 4.8% (16 of 332) of main curves and 8.8% (9/102) of minor curves. A similar range was reported by Stokes 3 in 1989 and more recently by Labaki et al 13 Furthermore, significant differences in the magnitude of rotation between the apicalAVR and the maxAVR values were seen in both major and minor curves. This, alongside a similar finding by Labaki et al, 13 suggests that in a significant number of cases the apical vertebra should not considered to be the most rotated, in contrast to the general belief since the early 1990s.…”

“…A similar range was reported by Stokes 3 in 1989 and more recently by Labaki et al 13 Furthermore, significant differences in the magnitude of rotation between the apicalAVR and the maxAVR values were seen in both major and minor curves. This, alongside a similar finding by Labaki et al, 13 suggests that in a significant number of cases the apical vertebra should not considered to be the most rotated, in contrast to the general belief since the early 1990s. 4,5 A significant difference between apicalAVR and maxAVR was seen across all severity groups and most Lenke classification groups.…”

“…12 The results of one recent EOS-based study of 158 patients are consistent with the early findings of Stokes 3 that while the apical vertebra is most commonly the maximally rotated vertebra, there can be a difference of 1 or 2 segments in 9.5% of cases. 13 The purpose of this study was to determine AVRs in the major and minor curves of adolescent idiopathic scoliosis using EOS 2D/3D imaging in a larger population, and to determine if the apical vertebra was the maximally rotated. According to our hypothesis, the apical vertebrae do not always have the largest axial rotation in adolescent idiopathic scoliosis.…”

“… 12 The results of one recent EOS-based study of 158 patients are consistent with the early findings of Stokes 3 that while the apical vertebra is most commonly the maximally rotated vertebra, there can be a difference of 1 or 2 segments in 9.5% of cases. 13 …”

A Novel Classification of 3D Rib Cage Deformity in Subjects With Adolescent Idiopathic Scoliosis

“…17 In the horizontal plane, the vertebrae are rotated, and the maximal rotation generally appears at the level of the apical vertebra. 18 This 3D deformity directly influences the chest wall through the costo-vertebral joints and leads to rib cage asymmetry, which in turn produces a gibbus, or rib hump. This gibbosity, often regarded as the fourth-dimension of scoliotic deformity, [19][20][21] was shown to be directly related to the Cobb angle 22 and was found to be the second most frequently cited factor leading patients to seek surgical treatment due to its esthetically unpleasant nature.…”