Leonidou Andreas, Moazen Mehran, Lepetsos Panagiotis, Graham Simon M, Macheras George A, Tsiridis Eleftherios
Academic Department of Orthopaedics and Trauma, Division of Surgery, Aristotle University Medical School, University Campus, 54 124 Thessaloniki, Greece.
Medical and Biological Engineering, School of Engineering, University of Hull, Hull HU6 7RX, UK.
Injury. 2015 Feb;46(2):213-7. doi: 10.1016/j.injury.2014.10.060. Epub 2014 Nov 1.
Optimal management of periprosthetic femoral fractures (PFF) around a well fixed prosthesis (Vancouver B1) remains controversial as adequate fixation needs to be achieved without compromising the stability of the prosthesis. The aim of this study was to highlight the effect of bone quality i.e. canal thickness ratio (CTR), and fracture topography i.e. fracture angle and its position in relation to the stem, on the biomechanics of a locking plate for a Vancouver B1 fracture. A previously corroborated simplified finite element model of a femur with a cemented total hip replacement stem was used in this study. Canal thickness ratio (CTR) and fracture topography were altered in several models and the effect of these variations on the von Mises stress on the locking plate as well as the fracture displacement was studied. Increasing the CTR led to reduction of the von Mises stress on the locking plate as well as the fracture movement. In respect to the fracture angle with the medial cortex, it was shown that acute angles resulted in lower von Mises stress on the plate as opposed to obtuse angles. Furthermore, acute fracture angles resulted in lower fracture displacement compared to the other fractures considered here. Fractures around the tip of the stem had the same biomechanical effect on the locking plate. However, fractures more distal to the stem led to subsequent increase of stress, strain, and fracture displacement. Results highlight that in good bone quality and acute fracture angles, single locking plate fixation is perhaps an appropriate management method. On the contrary, for poor bone quality and obtuse fracture angles alternative management methods might be required as the fixation might be under higher risk of failure. Clinical studies for the management of PFF are required to further support our findings.
对于固定良好的假体（温哥华B1型）周围的股骨假体周围骨折（PFF），最佳治疗方法仍存在争议，因为需要在不影响假体稳定性的前提下实现充分固定。本研究的目的是强调骨质量即髓腔厚度比（CTR）以及骨折形态即骨折角度及其与假体柄的位置关系对温哥华B1型骨折锁定钢板生物力学的影响。本研究使用了先前验证过的带有骨水泥全髋关节置换柄的股骨简化有限元模型。在多个模型中改变髓腔厚度比（CTR）和骨折形态，并研究这些变化对锁定钢板上的von Mises应力以及骨折位移的影响。增加CTR会导致锁定钢板上的von Mises应力以及骨折移动减少。关于与内侧皮质的骨折角度，结果表明锐角导致钢板上的von Mises应力低于钝角。此外，与这里考虑的其他骨折相比，锐角骨折导致的骨折位移更低。假体柄尖端周围的骨折对锁定钢板具有相同的生物力学影响。然而，假体柄更远端的骨折会导致应力、应变和骨折位移随后增加。结果表明，在骨质量良好且骨折角度为锐角的情况下，单锁定钢板固定可能是一种合适的治疗方法。相反，对于骨质量差和骨折角度为钝角的情况，可能需要其他治疗方法，因为固定失败的风险可能更高。需要进行关于PFF治疗的临床研究以进一步支持我们的发现。
