Hu Xiaobang, Siemionow Krzysztof B, Lieberman Isador H
Scoliosis and Spine Tumor Center, Texas Back Institute, Texas Health Presbyterian Hospital Plano, Plano, TX 75093, USA.
Department of Orthopaedic Surgery, University of Illinois Medical Center, Chicago, IL 60612 USA.
Int J Spine Surg. 2014 Dec 1;8. doi: 10.14444/1030. eCollection 2014.
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.
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.
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).
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.
椎弓根螺钉广泛应用于青少年特发性脊柱侧凸（AIS）手术。椎弓根螺钉位置不当可能导致严重的血管和神经并发症。对于外科医生而言，了解胸腰椎的形态测量解剖结构在植入椎弓根螺钉时至关重要。据报道，AIS患者侧弯凹侧的椎弓根宽度会减小。然而，性别是否在这种椎弓根宽度模式中起作用尚不清楚。本研究的目的是评估一组更同质化的AIS患者——Lenke 1型曲线的女性患者的椎体形态。
基于1mm层厚的CT扫描，分析了17例连续的Lenke 1型女性AIS患者的胸腰椎及椎弓根形态测量数据。研究了从T1到L5的539个椎弓根的形态测量解剖结构。测量包括椎弓根长度、弦长、椎弓根横向宽度、椎弓根横向角度和椎体旋转角度。
患者的平均年龄为14岁（范围12 - 18岁）。平均Cobb角为56°（范围43° - 88°），椎体平均旋转角度在4 - 13.8°之间。顶椎在T7和T11之间。胸椎顶区（T7和T8）凹侧的椎弓根横向宽度明显更小（p < 0.05），凹侧测量值在2.1 - 2.2mm之间，凸侧在2.7 - 3.1mm之间。同时，在一些上胸椎（T3、T4、T5），凹侧宽度明显大于凸侧（p < 0.05），凹侧测量值在2.8 - 4mm之间，凸侧在1.8 - 2.4mm之间。在腰椎，宽度在4.1 - 9.9mm之间，凹侧和凸侧之间无显著差异（p > 0.05）。椎弓根长度在15.4 - 28.7mm之间，在T4、T5和L2处凹侧明显更小（p < 0.05）。弦长在T1最短，为32.4mm，在L3逐渐增加到54.3mm，但凹侧和凸侧之间未发现统计学差异。椎弓根横向角度在11.8°和35°之间，在T7凹侧明显更大，在L1凸侧明显更大（p < 0.05）。
Lenke 1型女性AIS患者的椎体形态与正常脊柱的椎体形态有很大不同，尤其是在顶区和上胸椎区域。这与之前一些未区分男性和女性患者的报道一致。我们的研究结果表明，性别在AIS患者的椎体形态模式中不起主要作用。此外，认识到这种模式对于优化椎弓根螺钉内固定至关重要，并且无论植入方法如何，都可能允许在椎弓根螺钉轨迹上进行一些灵活调整。
