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Thoracic and lumbar vertebrae morphology in Lenke type 1 female adolescent idiopathic scoliosis patients.

Hu X, Siemionow KB, Lieberman IH - Int J Spine Surg (2014)

Bottom Line: The chord length was shortest at T1, measuring 32.4 mm and increased gradually to 54.3 mm at L3 but no statistical difference was found between the concave and convex sides.This is consistent with some previous reports which did not distinguish between male and female patients.Our findings suggest that gender does not play a major role in the vertebrae morphology pattern of AIS patients.

View Article: PubMed Central - PubMed

Affiliation: Scoliosis and Spine Tumor Center, Texas Back Institute, Texas Health Presbyterian Hospital Plano, Plano, TX 75093, USA.

ABSTRACT

Background: Pedicle screws are widely used in adolescent idiopathic scoliosis (AIS) surgeries. Pedicle screw malposition may lead to serious vascular and neurologic complications. Knowledge of the morphometric anatomy of the thoracic and lumbar vertebrae is essential for the surgeon while implanting pedicle screws. It has been reported that there is a reduction of pedicle width at the concavity of the curve in AIS patients. However, it is unclear if gender plays a role in this pedicle width pattern. The goal of this study is to assess the vertebrae morphology in a more homogeneous group of AIS patients - female patients with Lenke type 1 curve.

Methods: The thoracic and lumbar vertebra and pedicle morphometry of 17 consecutive Lenke type 1 female AIS patients was analyzed based on 1mm fine cut CT scans. Morphometric anatomy of 539 pedicles from T1 to L5 was studied. Measurements included pedicle length, chord length, transverse pedicle width, transverse pedicle angle and vertebral rotation angle.

Results: The mean age of the patients was 14 years old (range 12-18). The mean Cobb angle was 56° (range 43° -88°) and the mean angle of vertebral rotation varied between 4-13.8°. The apical vertebra was between T7 and T11. The transverse pedicle width was significantly smaller (p < 0.05) on the concave side in the apical region of the thoracic spine (T7 and T8), measuring between 2.1-2.2 mm on the concave side and 2.7-3.1 mm on the convex side. Meanwhile, in some upper thoracic vertebrae (T3, T4, T5), the width was significantly bigger (p < 0.05) on the concave side than on the convex side, measuring between 2.8-4 mm on the concave side and 1.8-2.4 mm on the convex side. In the lumbar spine, the width varied between 4.1-9.9 mm without significant differences between the concave and convex sides (p > 0.05). The pedicle length varied between 15.4-28.7 mm and was significantly smaller (p < 0.05) on the concave side at T4, T5 and L2. The chord length was shortest at T1, measuring 32.4 mm and increased gradually to 54.3 mm at L3 but no statistical difference was found between the concave and convex sides. The transverse pedicle angle varied between 11.8° and 35° and was significantly bigger on the concave side at T7 and on the convex side at L1 (p < 0.05).

Conclusions: The vertebrae morphology in Lenke type 1 female AIS patients is substantially different from the vertebrae in normal spines especially at the apex and in the upper thoracic region. This is consistent with some previous reports which did not distinguish between male and female patients. Our findings suggest that gender does not play a major role in the vertebrae morphology pattern of AIS patients. Furthermore, recognizing this pattern is critical in order to optimize pedicle screw instrumentation and may allow for some leeway adjustments in the pedicle screw trajectory regardless of the methods of implantation.

No MeSH data available.


Related in: MedlinePlus

A, Illustration of a thoracic vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).18, 24, 29, 30 B, Illustration of a lumbar vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).18, 24, 29, 30 C, Illustration of the angle of vertebral rotation (RAsag). RAsag is defined as the angle between the bisector of the bilateral longitudinal spinous-foraminal line and vertical axis.31–35
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Figure 0001: A, Illustration of a thoracic vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).18, 24, 29, 30 B, Illustration of a lumbar vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).18, 24, 29, 30 C, Illustration of the angle of vertebral rotation (RAsag). RAsag is defined as the angle between the bisector of the bilateral longitudinal spinous-foraminal line and vertical axis.31–35

Mentions: Vertebral body morphology including pedicle parameters were measured in all patients from pre-operative thin-cut (1mm) CT scans to characterize the anatomic dimensions. The CT scan is a standard procedure done for the preoperative planning of robotic assisted pedicle screw placement. The measurements included pedicle length, chord length, transverse pedicle width, transverse pedicle angle and angle of vertebral rotation. The pedicle length was measured as the distance from the posterior cortical entry point of the pedicle to the posterior longitudinal ligament along the axis of the pedicle. The chord length was measured as the distance between the posterior cortical entry point of the pedicle and the anterior vertebral cortex in line with the axis of the pedicle. The transverse pedicle width was measured as the endosteal width at the narrowest part of the pedicle. The transverse pedicle angle was measured as the angle between a line perpendicular to the transverse isthmus and a sagittal midvertebral line (Figure 1A, B). The angle of vertebral rotation (RAsag) was measured as the angle between the bisector of the bilateral longitudinal spinous-foraminal line and vertical axis (Figure 1C).


Thoracic and lumbar vertebrae morphology in Lenke type 1 female adolescent idiopathic scoliosis patients.

Hu X, Siemionow KB, Lieberman IH - Int J Spine Surg (2014)

A, Illustration of a thoracic vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).18, 24, 29, 30 B, Illustration of a lumbar vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).18, 24, 29, 30 C, Illustration of the angle of vertebral rotation (RAsag). RAsag is defined as the angle between the bisector of the bilateral longitudinal spinous-foraminal line and vertical axis.31–35
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4325490&req=5

Figure 0001: A, Illustration of a thoracic vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).18, 24, 29, 30 B, Illustration of a lumbar vertebra, showing the pedicle length (AB), the chord length (AC), the transverse pedicle width (DE) and the transverse pedicle angle (F).18, 24, 29, 30 C, Illustration of the angle of vertebral rotation (RAsag). RAsag is defined as the angle between the bisector of the bilateral longitudinal spinous-foraminal line and vertical axis.31–35
Mentions: Vertebral body morphology including pedicle parameters were measured in all patients from pre-operative thin-cut (1mm) CT scans to characterize the anatomic dimensions. The CT scan is a standard procedure done for the preoperative planning of robotic assisted pedicle screw placement. The measurements included pedicle length, chord length, transverse pedicle width, transverse pedicle angle and angle of vertebral rotation. The pedicle length was measured as the distance from the posterior cortical entry point of the pedicle to the posterior longitudinal ligament along the axis of the pedicle. The chord length was measured as the distance between the posterior cortical entry point of the pedicle and the anterior vertebral cortex in line with the axis of the pedicle. The transverse pedicle width was measured as the endosteal width at the narrowest part of the pedicle. The transverse pedicle angle was measured as the angle between a line perpendicular to the transverse isthmus and a sagittal midvertebral line (Figure 1A, B). The angle of vertebral rotation (RAsag) was measured as the angle between the bisector of the bilateral longitudinal spinous-foraminal line and vertical axis (Figure 1C).

Bottom Line: The chord length was shortest at T1, measuring 32.4 mm and increased gradually to 54.3 mm at L3 but no statistical difference was found between the concave and convex sides.This is consistent with some previous reports which did not distinguish between male and female patients.Our findings suggest that gender does not play a major role in the vertebrae morphology pattern of AIS patients.

View Article: PubMed Central - PubMed

Affiliation: Scoliosis and Spine Tumor Center, Texas Back Institute, Texas Health Presbyterian Hospital Plano, Plano, TX 75093, USA.

ABSTRACT

Background: Pedicle screws are widely used in adolescent idiopathic scoliosis (AIS) surgeries. Pedicle screw malposition may lead to serious vascular and neurologic complications. Knowledge of the morphometric anatomy of the thoracic and lumbar vertebrae is essential for the surgeon while implanting pedicle screws. It has been reported that there is a reduction of pedicle width at the concavity of the curve in AIS patients. However, it is unclear if gender plays a role in this pedicle width pattern. The goal of this study is to assess the vertebrae morphology in a more homogeneous group of AIS patients - female patients with Lenke type 1 curve.

Methods: The thoracic and lumbar vertebra and pedicle morphometry of 17 consecutive Lenke type 1 female AIS patients was analyzed based on 1mm fine cut CT scans. Morphometric anatomy of 539 pedicles from T1 to L5 was studied. Measurements included pedicle length, chord length, transverse pedicle width, transverse pedicle angle and vertebral rotation angle.

Results: The mean age of the patients was 14 years old (range 12-18). The mean Cobb angle was 56° (range 43° -88°) and the mean angle of vertebral rotation varied between 4-13.8°. The apical vertebra was between T7 and T11. The transverse pedicle width was significantly smaller (p < 0.05) on the concave side in the apical region of the thoracic spine (T7 and T8), measuring between 2.1-2.2 mm on the concave side and 2.7-3.1 mm on the convex side. Meanwhile, in some upper thoracic vertebrae (T3, T4, T5), the width was significantly bigger (p < 0.05) on the concave side than on the convex side, measuring between 2.8-4 mm on the concave side and 1.8-2.4 mm on the convex side. In the lumbar spine, the width varied between 4.1-9.9 mm without significant differences between the concave and convex sides (p > 0.05). The pedicle length varied between 15.4-28.7 mm and was significantly smaller (p < 0.05) on the concave side at T4, T5 and L2. The chord length was shortest at T1, measuring 32.4 mm and increased gradually to 54.3 mm at L3 but no statistical difference was found between the concave and convex sides. The transverse pedicle angle varied between 11.8° and 35° and was significantly bigger on the concave side at T7 and on the convex side at L1 (p < 0.05).

Conclusions: The vertebrae morphology in Lenke type 1 female AIS patients is substantially different from the vertebrae in normal spines especially at the apex and in the upper thoracic region. This is consistent with some previous reports which did not distinguish between male and female patients. Our findings suggest that gender does not play a major role in the vertebrae morphology pattern of AIS patients. Furthermore, recognizing this pattern is critical in order to optimize pedicle screw instrumentation and may allow for some leeway adjustments in the pedicle screw trajectory regardless of the methods of implantation.

No MeSH data available.


Related in: MedlinePlus