导航指引下打入股骨远近端的导针与股骨轴线间的关系

Relations between the femoral proximal and distal guide wires inserted with fluoroscopy-based computerized navigation and the femoral axis lines

目的研究导航指引下股骨远近端打入的导针与股骨轴线间关系,评估导针打入的准确性。方法首先获取5个完整的人造股骨模型。于导航指引下在每个股骨的近端和远端分别打入2枚和3枚导针,应用CT扫描模型储存数据后拔出导针。随后在股骨模型的股骨干中点,垂直于股骨长轴用电锯横形锯断股骨。分别将股骨远侧骨折块相对于近侧骨折块内旋5mm、内旋10mm、外旋5mm和外旋10mm。在这4个不同的位置上,用普通接骨板固定锯开的股骨块后再在股骨的远近端于导航指引下分别打入导针。重复CT扫描实验模型并储存数据。利用CT扫描图像的叠加技术分别测量股骨近端轴、髁轴和股骨远近端导针间的角度。结果股骨近端导针A和B分别与股骨近端设定的轴线1之间形成角度1A和1B。1B为(-0.316±2.678)°,1A为(0.348±2.717)°,两者相关系数r值为0.961。1A与1B间差值为(0.664±0.751)°,角度1A与1B间差异无统计学意义(P=0.792)。远端导针C、D和E分别与股骨远端股骨髁后缘的轴线2之间形成角度2C、2D和2E。2C为(0.760±2.792)°,2D为(-0.240±2.580)°,2E为(0.784±3.284)°,2C与2D、2C与2E、2D与2E的偏相关系数r值分别为0.883、0.886和0.867,三者间差异无统计学意义(P=0.387)。股骨近端导针B与远端导针C、D和E之间形成的夹角BC、BD和BE与股骨远近端轴线1和2形成的夹角12之间差值分别为(-1.672±3.651)°、(-1.880±3.730)°、(-1.236±3.537)°。3个角度差值间的差异无统计学意义(P>0.05)。结论在导航指引下打入的股骨远近端导针与术中所确定的股骨远近端轴线之间无明显差异,股骨远近端导针间的夹角可以真实地反映股骨的旋转角度。本研究所采用的方法可行性好,准确度高,为进一步研究该方法在临床的应用提供了坚实的实验基础。

Objective To investigate the relations between the guide wires inserted into the proximal and distal femur under the guidance of navigation system and the femoral proximal and distal axis lines, and to evaluate the accuracy of insertion. Methods Five artificial femoral bones were used in the study. Under the guidance of two-dimensional navigation system, two and three guide wires were inserted, into proximal and distal femur respectively. The guide wires were pulled out after CT scan. Femur was divided into two bone blocks at the midpoint of femoral shaft with a saw. The distal block was rotated externally 5 mm and 10 mm as well as internally 5 mm and 10 mm, respectively. At these four positions, a plate was used to fix femoral fracture and the guide wires were drilled into proximal and distal femur again. CT scans of the whole femur were taken again. The angles among the greater trochanter-femoral head landmark line, posterior line of femoral condyles and guide wires of proximal and distal femur were measured by image superimposition for CT scan. Results Angles 1A and 1B, the angles between the guide wire A and B of proximal femur and the greater trochanter-femoral head landmark line 1, were （0.348±2.717）° and （-0.316±2.678）°, respectively （r=0.961, P=0.792）. Angles 2C, 2D and 2E, the angles between the guide wire of C, D and E and the posterior line of femoral condyles 2, were （0. 760 ± 2.792）°, （-0. 240± 2. 580）° and （0. 784 ± 3. 284）°, respectively. The correlation coefficients between theangle 2C, 2D and 2E were 0. 883, 0. 886 and 0. 867, respectively, and there was no significant difference between the three angles （P=0.387）. Comparsion of the angle BC, BD and BE formed by the proximal guide wire B and the distal guide wire C, D and E with the angle 12 formed by the femoral proximal axis 1 and the femoral distal axis 2 showed that the the average differences were （- 1. 672±3.651）°, （- 1. 880±3.730）° and （-1.236± 3.537）°, respectively. There were no significant differences among the angle BC, BD and BE （P 〉 0. 05）. Conclusion Both the proximal and distal guide wire inserted under the guidance of navigation system are very close to the greater trochanter-femoral head landmark line and the posterior line of femoral condyles respectively. The intersection angles between the femoral proximal and distal guide wires truly represent the rotation deformity of the femur. This new method used in this study has good feasibility and high accuracy, with the ability to obtain the rotation angle of the femur in real-time and correct femoral rotation deformity in further application study in clinics.