Whitecloud T S, Skalley T C, Cook S D, Morgan E L
Department of Orthopaedic Surgery, Tulane University School of Medicine, New Orleans, LA 70112.
Clin Orthop Relat Res. 1989 Aug(245):57-68.
Potential complications due to pedicle screw penetration of the anterior cortex include injury to vascular, visceral, ureteral, sympathetic, and neural structures. This study examined the accuracy of lateral roentgenographic techniques in determining actual screw penetration in vertebral levels T12 through S1 of ten unilateral sets of pedicles in five anatomic specimens. A true lateral roentgenogram alone was inaccurate for determining the penetration of the anterior cortex by a pedicle screw. The greatest discrepancy between roentgenographically apparent and actual screw penetration was found at the L4 and L5 levels. Deviation from a true lateral roentgenographic axis resulted in the most pronounced change in roentgenographically apparent screw penetration at L4 and L5. The roentgenographic axes resulting in the closest approximation of actual screw penetrations were 5 degrees and 10 degrees above the true lateral axis for the T12-L3 and the L4-S1 levels, respectively. At 50% apparent penetration, the screw may be safely assumed to not be penetrating the anterior cortex using a true lateral roentgenogram. At 80% apparent penetration, 30% and 10% probabilities of actual screw penetration of the anterior cortex exist at L4 and L5, respectively. At 100% apparent penetration, there is an almost 100% probability that the screw is actually protruding through the anterior cortex.
椎弓根螺钉穿透椎体前皮质可能引起的并发症包括血管、内脏、输尿管、交感神经和神经结构损伤。本研究检查了侧位X线技术在确定5个解剖标本中10组单侧椎弓根T12至S1椎体水平螺钉实际穿透情况的准确性。仅通过一张真正的侧位X线片来确定椎弓根螺钉对椎体前皮质的穿透情况是不准确的。在X线片显示的螺钉穿透情况与实际穿透情况之间，最大差异出现在L4和L5水平。偏离真正的侧位X线轴会导致L4和L5水平在X线片上显示的螺钉穿透情况出现最明显的变化。对于T12-L3和L4-S1水平，分别在真正侧位轴上方5度和10度时，X线片显示的螺钉穿透情况与实际穿透情况最为接近。在X线片显示50%的穿透时，使用真正的侧位X线片可安全地假定螺钉未穿透椎体前皮质。在X线片显示80%的穿透时，L4和L5水平螺钉实际穿透椎体前皮质的概率分别为30%和10%。在X线片显示100%的穿透时，螺钉实际穿出椎体前皮质的概率几乎为100%。
