Zhang Wenxi, Ji Yueping, Wang Xinming, Liu Jie, Li Dong
Department of Orthopaedics, The Peoples' Hospital of Liyang, Changzhou, Jiangsu, PR China.
Department of Orthopaedics, The Peoples' Hospital of Liyang, Changzhou, Jiangsu, PR China.
Injury. 2017 Nov;48(11):2485-2495. doi: 10.1016/j.injury.2017.09.003. Epub 2017 Sep 6.
The mirror imaging 3D printing model can be used a as a reference for anatomical reduction in unilateral lower limb fractures. However, the premise of using mirror technology is that the bilateral lower limb bones are similar enough. Because one side had a fracture, it was impossible to compare this directly to the other side. Usually, surgeons think that the bilateral bones are symmetrical and use mirror technology without judging their symmetry.
In patients with a unilateral lower limb bone fracture, we measured the long axis and short axis of the three selected transverse sections of the bilateral long bone for comparison to judge the symmetry of the bilateral long bones on CT images. Then, we printed a life-size normal mirror image of the long bone that is similar to the affected side. The model was used as a reference for the anatomical reduction of fractures and preoperative practice.
Seventy-eight patients with lower limb bone fracture were included in this study. 24 groups of data were generated according to the same level and same axis. There were significant differences between the short axis of the left and right femoral condyle 5cm from the intercondylar keel (p=0.011), and the short axis of the distal tibia 15cm from the ankle dome (p=0.026). There was no significant difference between the left and right sides in the other 22 groups. Of all of the patients in our research, 3 patients decided to forego the surgical treatment and the operation was performed on the model instead, and the lengths of 2 patients showed deviation in actual operations, preventing anatomical reduction. The remaining 73 patients used the pre-bended plates and screws from preoperative practice in the actual operations, and postoperative X-ray examinations showed that the length of the deviation was within the permissible range.
The "Comparison of long axis and short axis of three equidistant transverse sections" method makes it easy to judge the symmetry of the bilateral long bones, and prevents the blindness of preoperative planning using the contralateral mirror model directly.
镜像3D打印模型可作为单侧下肢骨折解剖复位的参考。然而，使用镜像技术的前提是双侧下肢骨骼足够相似。由于一侧发生了骨折，无法直接与另一侧进行比较。通常，外科医生认为双侧骨骼是对称的，在未判断其对称性的情况下就使用了镜像技术。
对于单侧下肢骨折患者，我们在CT图像上测量双侧长骨三个选定横切面的长轴和短轴以作比较，判断双侧长骨的对称性。然后，我们打印出与患侧相似的长骨实物大小的正常镜像。该模型用作骨折解剖复位和术前练习的参考。
本研究纳入78例下肢骨折患者。根据相同水平和相同轴线生成24组数据。在距髁间嵴5cm处的左右股骨髁短轴（p = 0.011）以及距踝关节穹顶15cm处的胫骨干骺端短轴（p = 0.026）存在显著差异。其他22组左右两侧无显著差异。在我们研究的所有患者中，3例患者决定放弃手术治疗，转而在模型上进行手术，2例患者的长度在实际手术中出现偏差，无法进行解剖复位。其余73例患者在实际手术中使用了术前练习中预弯的钢板和螺钉，术后X线检查显示偏差长度在允许范围内。
“三个等距横切面长轴和短轴比较”方法便于判断双侧长骨的对称性，避免了直接使用对侧镜像模型进行术前规划的盲目性。
