Consecutive series of computed tomography (CT) of tibias and fibulae with no fracture or deformity were converted to stereo-lithograph format, and imported into Meshmixer software (Autodesk, San Rafael, California). A 3.6 × 180 mm fibula rod model was virtually inserted to best fit the intramedullary canal of the fibula model and to a depth of 0 mm proud at the distal fibula. The location of the entry point in relationship to the fibular tip, and the distance between the rod and the lateral fibula cortex were measured.
CT of 41 fibulae (23 male and 18 female patients) contributed to the three-dimensional fibula modeling. The entry point was 3.5 mm (SD 2.0) medial to (in mortise view) and 1.0 mm (SD 2.1) anterior to (in lateral view) the fibular tip. The fibula rod was inserted to a depth of 6.2 mm (SD 2.1) proximal to the fibula tip. The mean shortest distance of the rod to the outer cortex was 1.88 mm (SD 0.87). There was a breach of the posterolateral cortex in one patient.
The guide pin entry site of fibula rod should be medial and anterior offset with reference to the fibula tip, in contrary to the distal tip as recommended in the manual. There is a chance of breaching the posterolateral cortex with rod entry.
方法:将没有骨折或畸形的胫骨和腓骨的连续系列计算机断层扫描(CT)转换为立体光刻格式,并导入到Meshmixer软件(Autodesk,圣拉斐尔,California).实际上插入了3.6×180mm的腓骨棒模型,以最适合腓骨模型的髓内管,并在腓骨远端突出到0mm的深度。进入点相对于腓骨尖端的位置,并测量了棒与腓骨外侧皮质之间的距离。
结果:41例腓骨(男性23例,女性18例)的CT有助于腓骨的三维建模。入口点在腓骨尖端内侧(在榫槽视图中)为3.5mm(SD2.0),在腓骨尖端前方(在外侧视图中)为1.0mm(SD2.1)。将腓骨棒插入腓骨尖端近侧6.2mm(SD2.1)的深度。杆到外皮层的平均最短距离为1.88mm(SD0.87)。一名患者的后外侧皮质破裂。
结论:腓骨棒的导针进入部位应相对于腓骨尖端内侧和前方偏移,与手册中建议的远端尖端相反。杆进入有可能破坏后外侧皮层。