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Factors affecting pelvic rotation in idiopathic scoliosis

View Article: PubMed Central - PubMed

ABSTRACT

Pelvic rotation (PR) is commonly seen in patients with idiopathic scoliosis (IS), but factors contributing to this phenomenon and its relationship with the surgical outcome are not well established.

This retrospective study included 85 IS patients in 2 groups: thoracic curve dominance group (group A) and lumbar curve dominance group (group B). Pre- and postoperative PR was measured on standing posteroanterior radiographs by the left/right ratio (L/R ratio) of horizontal distance between the anterior superior iliac spine (ASIS) and the inferior ilium (SI) at the sacroiliac joint on the same side in both groups. Other radiographic data, age, sex, and Risser sign of each patient were recorded to analyze their correlations with PR before and after operation.

The patients ranged in age from 10 to 35 years with a mean of 17.0 ± 5.2 years. The mean L/R ratio of PR before operation was 0.99 (0.73–1.40) versus 0.98 (0.87–1.26) after operation. The L/R ration was beyond the range of 1 ± 0.1 (indicating the presence of PR) in 17 (20%) patients before operation and in 14 (16.5%) patients after operation. There was no significant difference in PR between the 2 groups of patients either before (P = 0.468) or after (P = 0.944) surgery. The preoperative PR showed a very low correlation with Risser sign (r = 0.220, P = 0.043), apex vertebral rotation (AVR) in the proximal thoracic curve (r = 0.242, P = 0.026), and AVR in the lumbar curve (r = 0.213, P = 0.049), while the postoperative PR showed a very low correlation with Risser sign (r = −0.341, P = 0.001) and postoperative trunk shift (TS) (r = −0.282, P = 0.009). Multiple stepwise regression analysis showed that preoperative PR was affected by proximal thoracic curve AVR and lumbar curve AVR.

There was no significant difference between PR before operation and 2 years after operation. Preoperative PR was mainly correlated with Risser sign and the rotation status of the proximal thoracic curve and lumbar curve, while postoperative PR was mainly correlated with Risser sign and postoperative TS.

No MeSH data available.


Related in: MedlinePlus

A standing posterior–anterior radiograph of a 14-year-old girl with thoracic curve dominance illustrating the measurements of L/R ratio of ASIS-SI and TS. ASIS = anterior-superior iliac spine, L/R ratio = left/right ratio, SI = inferior ilium at the sacroiliac joint, TS = trunk shift.
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Figure 1: A standing posterior–anterior radiograph of a 14-year-old girl with thoracic curve dominance illustrating the measurements of L/R ratio of ASIS-SI and TS. ASIS = anterior-superior iliac spine, L/R ratio = left/right ratio, SI = inferior ilium at the sacroiliac joint, TS = trunk shift.

Mentions: Posteroanterior full-length X-ray radiography of the whole spine was performed in a standard position before surgery and during the 2-year follow-up period after surgery in all IS patients, on which coronal Cobb angle, the degree of Nash-Moe rotation of the apical vertebra and Risser sign were measured. Coronal balance was represented as the horizontal distance between the central sacral vertical line (CSVL) and C7 plumb line (C7PL), and a C7PL presents on the left or right side of the CSVL was designated as the negative or positive value, respectively. TS was measured on the standing posteroanterior X-ray radiographs. First, the apical vertebra of thoracic curve was determined, and then a horizontal line (ab) was drawn through its central point, where points a and b represent the crossover point between the horizontal reference line across the central point of the apical vertebra of the thoracic curve and the left and right boundary of the bony thorax, respectively. The midpoint of the a–b line is c, through which a vertical line was made as the vertical trunk reference line. TS was referred to as the distance (mm) between the vertical trunk reference line and CSVL. Displacement of TS to the right side of CSVL was recorded as the positive value, and that to the left side was recorded as the negative value. Horizontal PR was measured as described.[10] First, the horizontal distance between the anterior superior iliac spine (ASIS) and the inferior ilium (SI) at the sacroiliac joint on the same side was measured on the whole-spine posteroanterior view of X-ray radiography, and then the left/right (L/R) ratio of ASIS-SI was used to represent the degree of horizontal PR (Fig. 1). An L/R ratio of ASIS-SI smaller than 1 indicated right PR in the cephalad view, and vice versa. An L/R ratio within the range of 1 ± 0.1 was defined as physiologic symmetry of the pelvis without the presence of horizontal PR or only minimal rotation. The IS patients were further classified into 2 groups: group A of thoracic curve dominance (equivalent to Lenke I–III) and group B of lumbar curve dominance (equivalent to Lenke V–VI). All imaging data were obtained twice by 2 doctors independently, with the interval between the 2 measurements no <2 weeks. The mean value of the 2 measurements from the 2 doctors was used for analysis.


Factors affecting pelvic rotation in idiopathic scoliosis
A standing posterior–anterior radiograph of a 14-year-old girl with thoracic curve dominance illustrating the measurements of L/R ratio of ASIS-SI and TS. ASIS = anterior-superior iliac spine, L/R ratio = left/right ratio, SI = inferior ilium at the sacroiliac joint, TS = trunk shift.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120956&req=5

Figure 1: A standing posterior–anterior radiograph of a 14-year-old girl with thoracic curve dominance illustrating the measurements of L/R ratio of ASIS-SI and TS. ASIS = anterior-superior iliac spine, L/R ratio = left/right ratio, SI = inferior ilium at the sacroiliac joint, TS = trunk shift.
Mentions: Posteroanterior full-length X-ray radiography of the whole spine was performed in a standard position before surgery and during the 2-year follow-up period after surgery in all IS patients, on which coronal Cobb angle, the degree of Nash-Moe rotation of the apical vertebra and Risser sign were measured. Coronal balance was represented as the horizontal distance between the central sacral vertical line (CSVL) and C7 plumb line (C7PL), and a C7PL presents on the left or right side of the CSVL was designated as the negative or positive value, respectively. TS was measured on the standing posteroanterior X-ray radiographs. First, the apical vertebra of thoracic curve was determined, and then a horizontal line (ab) was drawn through its central point, where points a and b represent the crossover point between the horizontal reference line across the central point of the apical vertebra of the thoracic curve and the left and right boundary of the bony thorax, respectively. The midpoint of the a–b line is c, through which a vertical line was made as the vertical trunk reference line. TS was referred to as the distance (mm) between the vertical trunk reference line and CSVL. Displacement of TS to the right side of CSVL was recorded as the positive value, and that to the left side was recorded as the negative value. Horizontal PR was measured as described.[10] First, the horizontal distance between the anterior superior iliac spine (ASIS) and the inferior ilium (SI) at the sacroiliac joint on the same side was measured on the whole-spine posteroanterior view of X-ray radiography, and then the left/right (L/R) ratio of ASIS-SI was used to represent the degree of horizontal PR (Fig. 1). An L/R ratio of ASIS-SI smaller than 1 indicated right PR in the cephalad view, and vice versa. An L/R ratio within the range of 1 ± 0.1 was defined as physiologic symmetry of the pelvis without the presence of horizontal PR or only minimal rotation. The IS patients were further classified into 2 groups: group A of thoracic curve dominance (equivalent to Lenke I–III) and group B of lumbar curve dominance (equivalent to Lenke V–VI). All imaging data were obtained twice by 2 doctors independently, with the interval between the 2 measurements no <2 weeks. The mean value of the 2 measurements from the 2 doctors was used for analysis.

View Article: PubMed Central - PubMed

ABSTRACT

Pelvic rotation (PR) is commonly seen in patients with idiopathic scoliosis (IS), but factors contributing to this phenomenon and its relationship with the surgical outcome are not well established.

This retrospective study included 85 IS patients in 2 groups: thoracic curve dominance group (group A) and lumbar curve dominance group (group B). Pre- and postoperative PR was measured on standing posteroanterior radiographs by the left/right ratio (L/R ratio) of horizontal distance between the anterior superior iliac spine (ASIS) and the inferior ilium (SI) at the sacroiliac joint on the same side in both groups. Other radiographic data, age, sex, and Risser sign of each patient were recorded to analyze their correlations with PR before and after operation.

The patients ranged in age from 10 to 35 years with a mean of 17.0&#8202;&plusmn;&#8202;5.2 years. The mean L/R ratio of PR before operation was 0.99 (0.73&ndash;1.40) versus 0.98 (0.87&ndash;1.26) after operation. The L/R ration was beyond the range of 1&#8202;&plusmn;&#8202;0.1 (indicating the presence of PR) in 17 (20%) patients before operation and in 14 (16.5%) patients after operation. There was no significant difference in PR between the 2 groups of patients either before (P&#8202;=&#8202;0.468) or after (P&#8202;=&#8202;0.944) surgery. The preoperative PR showed a very low correlation with Risser sign (r&#8202;=&#8202;0.220, P&#8202;=&#8202;0.043), apex vertebral rotation (AVR) in the proximal thoracic curve (r&#8202;=&#8202;0.242, P&#8202;=&#8202;0.026), and AVR in the lumbar curve (r&#8202;=&#8202;0.213, P&#8202;=&#8202;0.049), while the postoperative PR showed a very low correlation with Risser sign (r&#8202;=&#8202;&minus;0.341, P&#8202;=&#8202;0.001) and postoperative trunk shift (TS) (r&#8202;=&#8202;&minus;0.282, P&#8202;=&#8202;0.009). Multiple stepwise regression analysis showed that preoperative PR was affected by proximal thoracic curve AVR and lumbar curve AVR.

There was no significant difference between PR before operation and 2 years after operation. Preoperative PR was mainly correlated with Risser sign and the rotation status of the proximal thoracic curve and lumbar curve, while postoperative PR was mainly correlated with Risser sign and postoperative TS.

No MeSH data available.


Related in: MedlinePlus