Graham Simon M, Mak Jonathan H, Moazen Mehran, Leonidou Andreas, Jones Alison C, Wilcox Ruth K, Tsiridis Eleftherios
Institute of Medical and Biological Engineering, University of Leeds, Leeds, LS2 9JT, UK.
School of Engineering, University of Hull, Hull, HU6 7RX, UK.
J Orthop Sci. 2015 Sep;20(5):875-80. doi: 10.1007/s00776-015-0735-3. Epub 2015 May 13.
The incidence of periprosthetic femoral fractures (PFF) around a stable stem is increasing. The aim of this biomechanical study was to examine how three different methods of fixation, for Vancouver type B1 PFF, alter the stiffness and strain of a construct under various configurations, in order to gain a better insight into the optimal fixation method.
Three different combinations of proximal screws and Dall-Miles cables were used: (A) proximal unicortical locking screws alone; (B) proximal cables and unicortical locking screws; (C) proximal cable alone, each in combination with distal bicortical locking screws, to fix a stainless steel locking compression plate to five synthetic femora with simulated Vancouver type B1 PFFs. In one synthetic femora, there was a 10-mm fracture gap, in order to simulate a comminuted injury. The other four femora had no fracture gap, to simulate a stable injury. An axial load was applied to the constructs at varying degrees of adduction, and the overall construct stiffness and surface strain were measured.
With regards to stiffness, in both the gap and no gap models, method of fixation A was the stiffest form of fixation. The inclusion of the fracture gap reduced the stiffness of the construct quite considerably for all methods of fixation. The strain across both the femur and the plate was considerably less for method of fixation C, compared to A and B, at the locations considered in this study.
This study highlights that the inclusion of cables appears to damage the screw fixations and does not aid in construct stability. Furthermore, the degree of fracture reduction affects the whole construct stability and the bending behaviour of the fixation.
稳定型股骨柄周围的人工关节周围股骨骨折（PFF）发病率正在上升。这项生物力学研究的目的是研究三种不同的固定方法如何改变温哥华B1型PFF在各种配置下的结构刚度和应变，以便更好地了解最佳固定方法。
使用近端螺钉和Dall-Miles缆线的三种不同组合：（A）仅近端单皮质锁定螺钉；（B）近端缆线和单皮质锁定螺钉；（C）仅近端缆线，每种组合均与远端双皮质锁定螺钉一起，将不锈钢锁定加压钢板固定到五个模拟温哥华B1型PFF的合成股骨上。在一个合成股骨中，有一个10毫米的骨折间隙，以模拟粉碎性损伤。其他四个股骨没有骨折间隙，以模拟稳定损伤。在不同程度的内收情况下对结构施加轴向载荷，并测量整体结构刚度和表面应变。
关于刚度，在有间隙和无间隙模型中，固定方法A是最硬的固定形式。对于所有固定方法，骨折间隙的存在都相当大地降低了结构的刚度。与A和B相比，在本研究考虑的位置，固定方法C在股骨和钢板上的应变都要小得多。
本研究强调，使用缆线似乎会损害螺钉固定，并且无助于结构稳定性。此外，骨折复位程度会影响整个结构的稳定性和固定的弯曲行为。
