Analysis of the cervical spine sagittal alignment in young idiopathic scoliosis: a morphological classification of 120 cases

Abstract

Purpose To analyze the relationship between the cervical spine and global spinal-pelvic alignment in young patients with idiopathic scoliosis based on a morphological classification, and to postulate the hypothesis that cervical kyphosis is a part of cervico-thoracic kyphosis in them. Methods 120 young patients with idiopathic scoliosis were recruited retrospectively between 2006 and 2011. The following values were measured and calculated: cervical angles (CA), cervico-thoracic angles (CTA), pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), spinal sacral angle (SSA), hip to C7/hip to sacrum, thoracic kyphosis (TK), lumbar lordosis (LL), Roussouly sagittal classification, Lenke Type Curve and Lumbar Modifier. The cervical curves were classified as lordosis, straight, sigmoid and kyphosis. They were categorized into four groups as cervical non-kyphosis group (CNK Group), cervical kyphosis group (CK Group), cervical-middle-thoracic kyphosis group (CMTK Group), and cervical-lower-thoracic kyphosis group (CLTK Group) according to their morphological characters of sagittal alignments. All parameters were compared and analyzed among groups. Results The incidence of cervical kyphosis was 40 % (48/ 120). The CA and the CTA were in significant correlation (r = 0.854, P = 0.00). The cervical spine alignments were revealed to be significantly different among groups (r = 85.04, P = 0.00). Significant differences among groups in CA, CTA and TK were also detected. A strong correlation between the group type and Lenke Lumbar Modifier was still seen (P \ 0.05). Fisher's exact test revealed that the individual vertebral body kyphosis and wedging were directly related to the overall cervical kyphosis (P = 0.00, respectively). Conclusion The cervical kyphosis is correlated with global sagittal alignment, and is a part of cervico-thoracic sagittal deformity in young patients with idiopathic scoliosis. Despite the deformity in cervical alignment, the global spine could still be well-balanced with spontaneous adjustment. The correlation between our grouping based on the morphological characteristics of the sagittal alignments and Lenke Lumbar Modifier suggests that the coupled motion principle be appropriate to explain the modifications both in coronal and sagittal planes.

Analysis of the relationship between coronal and sagittal deformities in adolescent idiopathic scoliosis

“…This study found that 72.4 % of the recruited subjects stood with C7 plumbline behind HA and supero-posterior corner of S1. The proportion is similar to Yu's report in scoliotic population but lower than that in Mac-Thiong's report in normal Caucasian population [12,14]. Thus, as pointed out previously, the anterior shift of C7 plumbline may indicate the risk of the development of sagittal spinal imbalance, and the possible underlying pathology should be screened and identified [14,19,25].…”

“…*Statistically significant at P \ 0.05. Oneway ANOVA test [11] but lower than that of Caucasian counterparts [7][8][9]12]. Besides, previous comparison studies reported similar PI between the two groups with a thoracic or lumbar curve [8,9], which was echoed by this study (Table 4).…”

“…Recently, the deformity of spine on coronal and sagittal planes has been separately explored and characterized in the patients with adolescent idiopathic scoliosis (AIS) [4][5][6][7][8][9][10][11][12], and correlation has been proven to exist between different sagittal spino-pelvic parameters [7,10,12,[14][15][16][17][18]. However, the relationship of the parameters on different planes has been seldom explored, except for some comparative studies between the groups with a thoracic or lumbar curve in AIS patients [8,9,11].…”

Cervical spine alignment following lumbar pedicle subtraction osteotomy for sagittal imbalance

“…Reciprocal changes outside of the fused segments have previously been reported for the thoracic, lumbar and pelvic regions [7][8][9][10][11]. It has also been noted that changes in global spinal alignment following surgery affect the alignment of the cervical region [12][13][14][15].…”

Variations of cervical lordosis and head alignment after pedicle subtraction osteotomy surgery for sagittal imbalance

“…The variation of cervical alignment after surgery for sagittal imbalance has received less attention in the scientific literature. Only recently, a few papers discuss on cervical alignment after surgery for idiopathic scoliosis [10,11], or correction of sagittal imbalance in adults [12,13]. A deeper comprehension of the mechanisms and of the changes that take place at the cervical spine in sagittal malalignment and after corrective surgery is of interest to anticipate potential reciprocal influences in patients with spinal deformity.…”