外加中空螺釘在內側支撐骨板固定股骨頸骨折中所扮演的角色

Role of Cannulated Screws in the Fixation of Pauwels III 70-Degree Femoral Neck Fractures with a Medial Buttress Locking Plate

使用內側支撐骨板加上三根中空螺釘可以有效固定垂直型股骨頸骨折，然而，要將三根中空螺釘與內側支撐骨板一同植入股骨頸狹小的空間內是一項技術要求極高的手術。為了在穩定度和植入的中空螺釘數量間取得平衡，本研究使用有限元素模型來比較內側支撐骨板搭配不同數量的中空螺釘配置對股骨頸骨折固定的穩定度差異。本研究建立了一個股骨頸骨折的有限元素模型，骨折間隙為1毫米且骨折面與水平面之夾角為70度。本研究比較的固定方式包括內側支撐骨板加上三根平行的中空螺釘成朝下三角形的配置、兩根中空螺釘以及一根中空螺釘。此外，一根中空螺釘的位置差異，位於股骨頸的前、中和後，亦會納入分析與比較。結果顯示，使用內側支撐骨板加上三根與兩根中空螺釘的模型，股骨頭最大位移量與骨折間隙的變化量皆明顯小於只有使用一根中空螺釘的模型，且使用內側支撐板能夠防止骨折間隙下緣的坍塌量，但是，骨板的等效應力亦會明顯高於中空螺釘的應力。根據目前的結果，建議在處理骨折面接近垂直面類型的股骨頸骨折時，除了內側支撐骨板外，最少加上兩支以上的中空螺釘，以確保骨折處之穩定度，不建議只加上一隻中空螺釘，以免因為骨折處的不穩定引發後續併發症。

A medial buttress locking plate and three cannulated screws have been proposed for the management of Pauwels III femoral neck fractures. However, the implantation of three cannulated screws together with the medial buttress locking plate is a highly demanding technique. To maintain a balance between the number of cannulated screws and the stability of the fixation in Pauwels III femoral neck fractures, this study compared the mechanical stability of a fractured femur with a medial buttress plate and different configurations of cannulated screws with finite element (FE) simulation. An FE hip model with a fractured femur neck fixed using different fixation approaches was created in this study. The fracture was defined as Pauwels III femoral neck fracture with a 1-mm gap. The approaches used included three traditional parallel cannulated screws in a downward triangular configuration, a medial buttress locking plate along with three cannulated screws in a downward triangular configuration, two superior screws, and one cannulated screw. Furthermore, different locations, namely, the anterior, middle, and posterior to the femoral neck, were considered for the cannulated screw. The results indicated that the gap deformation and the displacement of the fractured femur head with the medial buttress plate along with two and three cannulated screws were significantly smaller than that with the medial buttress plate along with one cannulated screw and just three cannulated screws. Furthermore, the medial buttress plate could prevent the inferior part of the fracture gap from collapsing under loading. However, the stress of the locking plate and screws was higher than that of the cannulated screws. Based on the present simulation, instead of one cannulated screw, two superiorly placed cannulated screws or three cannulated screws placed in a downward triangular configuration are recommended in combination with a medial buttress locking plate for the management of Pauwels III femoral neck fractures.