C臂X线机不同投射角度透视对股骨颈骨折经皮内固定后上方in-out-in螺钉的评估

目的 探讨采用C臂X线机不同投射角度透视图像评估股骨颈骨折经皮内固定模型后上方in-out-in（IOI）螺钉的精准性。方法 选取6个Synbone股骨近端人工骨标准模型,模拟股骨颈骨折经皮倒三角空心螺钉内固定手术方式向股骨颈内分别置入3枚2.5 mm的导针,其中后上方的那枚导针设计成IOI状态。使用C臂X线机,观察以下不同投射角度X线透视图像上股骨颈后上方的IOI导针穿出皮质的情况：（1）标准正侧位和轴位透视;（2）动态旋转手术床透视;（3）C臂X线机顺序旋转透视。结果 （1）6个模型的标准正侧位透视图像均显示置入的3枚导针完全位于股骨颈内,未见穿破皮质;股骨颈轴位透视均可见后上方IOI导针明显穿出皮质。（2）逆时针旋转手术床与水平面约20°时透视可发现IOI导针穿出皮质。（3）C臂X线机影像增强器顺时针旋转40°时,可清晰观察到IOI导针穿破了皮质,在股骨颈内呈现IOI状态。结论 C臂X线机正侧位透视图像在评估股骨颈骨折经皮内固定后上方的IOI螺钉时存在假象,而使用40°顺时针旋转透视的图像可清晰显示股骨颈后上方IOI螺钉。

C-arm X-ray fluoroscopy with different projection angles in the evaluation of "in-out-in" posterosuperior screws during percutaneous internal fixation of femoral neck fractures

Objective This study was performed to explore the accuracy of C-arm X-ray fluoroscopic images at different projection angles in the evaluation of in-out-in (IOI) posterosuperior screws during percutaneous internal fixation of femoral neck fractures. Methods Six Synbone standard models of proximal femur artificial bone were selected. Then, three 2.5-mm guide pins were placed into the femoral neck according to the same method by simulating percutaneous inverted triangular hollow screw fixation, of which the posterosuperior one was intentionally designed as IOI. C-arm X-ray machine was used to observe the penetration of the IOI guide pin at the posterosuperior side of the femoral neck through the cortex on C-arm X-ray fluoroscopic images at different projection positions: standard adem position and lateral fluoroscopic images and axial fluoroscopy; fluoroscopy after dynamic rotation of the operating bed at a certain angle to the horizontal plane; and sequential rotation fluoroscopy of the C-arm X-ray. Results The standard anteroposterior and lateral fluoroscopic images of the six models showed that the three guide pins were completely located in the femoral neck, and no perforation of the cortex was observed. Axial perspective of the femoral neck showed that the IOI guide pin obviously pierced through the cortex. When the operating bed was rotated at approximately 20° counterclockwise, the fluoroscopy showed that the IOI guide pin penetrated the cortex. When the C-arm image intensifier was sequentially rotated at 40°, the IOI guide pin penetrated the cortex and showed an IOI state in the femoral neck. Conclusion The adem position and lateral fluoroscopic images showed a false appearance in the evaluation of the IOI posterosuperior screws during percutaneous internal fixation of femoral neck fractures. Images with 40° sequential rotation fluoroscopy clearly showed the IOI posterosuperior screws of the femoral neck.