股骨髓腔的解剖学测量及与股骨交锁髓内钉的匹配性研究

Research on geometric feature of femoral medullary cavity and it＇s matching with intramedullary nail

目的通过CT扫描图像对股骨髓腔进行解剖学测量，模拟分析髓腔与股骨交锁髓内钉的匹配性，探讨髓内钉手术中远端锁钉置人困难的原因。方法对30个干燥股骨标本进行CT横断面扫描，每一个股骨按骨干全长均匀提取20幅图像，分别测量每幅图像中轴点及髓腔壁一周8个点在X、Y轴上的数据。用三维绘图软件画出髓腔、中轴线、髓内钉在三维空间上的形态，重叠后进行比对。绘制髓腔中轴冠状面及矢状面的折线型数据图表，与髓内钉数据结合，模拟髓内钉插入髓腔，观察髓内钉切出髓腔壁情况。结果将股骨髓腔中轴线与髓内钉重叠后进行比对，二者在冠状面上较一致，在矢状面上髓腔弧度较髓内钉大。模拟髓内钉插入髓腔，冠状面上有6根髓内钉于股骨标本的中上段切出髓腔内侧或外侧壁，切出率为20％（6／30），矢状面上有13根髓内钉从前缘切出，切出率为43％（13／30）。结论常规股骨交锁髓内钉与大多数股骨髓腔匹配，但髓腔解剖结构有一定的变异性，部分髓腔成角过大使髓内钉发生形变是引起髓内钉远端锁钉置入困难的主要原因。

Objective To＇investigate the geometric feature of femoral medullary cavity through CT scanning and it＇s matching with femoral intramedullary nail, and to analysis the reason for difficulties in implanting distal lock pin. Methods Thirty dried femur specimens were measured through CT scanning, and twenty images were taken evenly according to the total length of shaft of femur from each femur. In each image, the data of the central axis point and eight points around medullary cavity wall in X and Y axes were obtained, which were used to reconstruct the three-dimensional models of medullary cavity, central axis, intramedullary nail by computer software. And the models were overlapped for comparison. Then the coronal and sagittal fold line charts for central axis of medullary cavity were drawn. The inserting process of intramedullary nail was simulated to observe whether the nail would punch out of the medullary cavity wall. Results The central axis of femoral medullary cavity and intramedullary nail were overlapped and compared. They matched well in the coronal plane, but the curves of femoral medullary cavity were larger than those of intramedullary nails in sagittal plane. While simulating the inserting process of intramedullary nail, 6 nails punched out of the medullary cavity wall in coronal plane （20%, 6/30）, so did 13 nails in sagittal plane （43%, 13/30）. Conclusion Intramedullary nails match well with most of the femoral medullary cavities. However, the anatomic structure of the femoral medullary cavity differs individually. Curves of some femoral medullary cavity are large, which can cause deformation of intramedullary nail, and this is the main reason for the failure of distal locking.