后凸成形术经皮穿刺与椎弓根螺钉植入内倾角的影像学研究

The image study of leaning inside angle in percutaneous balloon kyphoplasty and pedicle screw insertion

目的探讨后凸成形术经皮穿刺与椎弓根螺钉植入内倾角的差异，为后凸成形术治疗骨质疏松性椎体压缩性骨折术中准确穿刺提供影像学依据。方法选取正常胸腰椎（T8-L5）CT图像120椎，借助计算机软件测量椎弓根螺钉植入内倾角及后凸成形术穿刺方向内倾角及各相关参数，统计分析后凸成形术经皮穿刺与椎弓根螺钉植入内倾角的差异。结果椎弓根内倾角与椎弓根侧距、椎序呈正相关，随着椎序的递增，椎弓根侧距逐渐增大，内倾角也逐渐增大，k的椎弓根内倾角最大；椎体前外侧壁的宽度与对称性即椎体前1／4侧距与椎弓根内倾角呈负相关，其值越小，椎体前外侧壁越扁平，椎弓根内倾角也就越大，术中要求经椎弓根穿刺的角度也越大，反之亦然；后凸成形术穿刺方向较椎弓根轴线内倾角大（13．27°±0．16°）；椎弓根螺钉植入内倾角较椎弓根内倾角大（6．87°±0．09°）；后凸成形术穿刺方向较椎弓根螺钉植入内倾角大（6．40°±0．07°）。结论椎弓根螺钉植入内倾角应较椎弓根轴线内倾角略大，以防止螺钉穿破椎体前外侧壁并获得更佳的钉道深度；后凸成形术穿刺方向应较椎弓根螺钉植入内倾角大，以获得球囊在椎体内的最佳位置。

Objective To discuss the differences of leaning inside angle between the percutaneous balloon kyphoplasty and pedicle screw insertion, and provide the reference of exactly puncturing in kyphoplasty for osteoporotic vertebral compression fractures. Methods The CT images of 120 normal thoracolumbar vertebra （T8-L5） in six normal adult specimens were selected to measure the leaning inside angles of pedicle axis, kyphoplasty and pedicle screw by the Computer Dynamic Measure. The differences of the leaning inside angle between the percutaneous balloon kyphoplasty and pedicle screw insertion were analyzed. Results There was positive correlation between the leaning inside angle and the pedicle lateral distance and level, with the level increased the pedicle lateral distance increased and the leaning inside angle also increased, so the highest angle was in L 5. The width and the symmetry of anterior wall also affected the puncture direction through the pedicle approach and there was negative correlation between the parameter lateral distance in anterior quarter of the vertebra and the angle. The kyphoplasty angle was more （13.27°± 0.16°） than pedicle axis, and the angle of pedicle screw was more （6.87°±0.09°） than pedicle axis, but the kyphoplasty angle was more （6.40°±0.07°） than pedicle screw. Conclusion The leaning inside angle of pedicle screw should be more than pedicle axis to prevent the screw penetrate through the anterolateral wall as well as get the best screw path depth. The kyphoplasty angle should be more than pedicle screw angle to get the best balloon position in the vertebra.