McLain Robert F, Ferrara Lisa, Kabins Mark
Department of Orthopaedic Surgery, and the Spine Research Laboratory, the Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA.
Spine (Phila Pa 1976). 2002 Nov 15;27(22):2467-71. doi: 10.1097/00007632-200211150-00009.
An anatomic study of pedicle dimensions and orientation was performed for upper thoracic vertebrae from elderly human subjects.
To quantify dimensions of thoracic pedicles, and to determine the potential for safe transpedicular screw fixation in the upper thoracic spine.
Clinical and anatomic reports support thoracic pedicle fixation as a safe, effective alternative to hook fixation in both normal and osteoporotic bone. Much available data, however, pertains to young, robust patients, thoracolumbar segments, and mixed placement techniques.
For this study, T1-T6 vertebrae from 18 human cadavers were separated into individual vertebrae. Examiners measured each vertebra to determine medial-lateral pedicle width, cranial-caudal pedicle height, and coaxial depth from lamina to anterior vertebral cortex. Mean values were derived from repeated measures compared by level and side.
Dimension a varied with individual and level, but not between the left and right pedicles. Pedicle diameter uniformly diminished as specimens proceeded caudally from T2. Findings showed that 25% of T1 pedicles, 17% of T2 pedicles, and 42% of T3 pedicles were narrower than 5.5 mm. At T4 61% of pedicles were too small, at T5 67% were too small, and at T6 75% were too small to accept a 5.5-mm screw. Dimension b remained relatively constant. Pedicles became increasingly narrow and oblong in the T4-T6 cross sections. Dimension c increased consistently from T1 to T6. Safe screw lengths ranged from 30 mm at T1 and T2, to 35 mm at T4 -T5, to 40 mm at T5 and T6.
Even the largest patients had some pedicles that could not accommodate the smallest standard pedicle screw, and more than one half of the pedicles average patients were too small. Transpedicular screw placement is not safe in these patients. Proper placement must avoid penetration of the medial pedicle wall.
对老年人体上胸椎的椎弓根尺寸和方向进行解剖学研究。
量化胸椎椎弓根的尺寸，并确定上胸椎安全经椎弓根螺钉固定的可能性。
临床和解剖学报告支持在正常和骨质疏松骨中，胸椎椎弓根固定是一种安全、有效的钩状固定替代方法。然而，现有的许多数据涉及年轻、健壮的患者、胸腰段以及混合置入技术。
在本研究中，将18具人类尸体的T1 - T6椎体分离为单个椎体。检查者测量每个椎体，以确定椎弓根的内外宽度、头尾方向的椎弓根高度以及从椎板到椎体前皮质的同轴深度。通过水平和侧别比较重复测量得出平均值。
尺寸a因个体和水平而异，但左右椎弓根之间无差异。随着标本从T2向尾端推进，椎弓根直径均匀减小。结果显示，25%的T1椎弓根、17%的T2椎弓根和42%的T3椎弓根窄于5.5毫米。在T4，61%的椎弓根太小，在T5，67%太小，在T6，75%太小，无法容纳5.5毫米的螺钉。尺寸b保持相对恒定。在T4 - T6横切面中，椎弓根变得越来越窄且呈椭圆形。尺寸c从T1到T6持续增加。安全螺钉长度范围从T1和T2处的30毫米，到T4 - T5处的35毫米，再到T5和T6处的40毫米。
即使是体型最大的患者，也有一些椎弓根无法容纳最小的标准椎弓根螺钉，且平均体型患者超过一半的椎弓根太小。在这些患者中经椎弓根螺钉置入不安全。正确的置入必须避免穿透椎弓根内侧壁。
