Filipov Orlin, Gueorguiev Boyko
Vitosha Hospital, Simeonovsko Shose Str. 108-B, 1700 Sofia, Bulgaria.
AO Research Institute Davos, Clavadelerstrasse 8, 7270 Davos, Switzerland.
Injury. 2015 Feb;46(2):218-26. doi: 10.1016/j.injury.2014.11.013. Epub 2014 Nov 27.
Osteosynthesis of femoral neck fractures is related to 20-46% complication rate. Filipov's novel method for biplane double-supported screw fixation (BDSF), using three cannulated screws, has demonstrated excellent clinical results since 2007. Its two calcar-buttressed screws are oriented in different coronal inclinations with steeper angles to the diaphyseal axis and intended to provide constant fixation strength under different loading situations. The aim of this study was to biomechanically evaluate BDSF fixation strength and compare it with the conventional fixation (CFIX) using three parallel cannulated screws.
Eight fresh-frozen and six embalmed human femoral pairs with simulated AO/OTA31-B2.2 fracture were fixed applying either CFIX or BDSF. Quasistatic tests were performed in anteroposterior (AP) bending, followed by axial quasistatic, cyclic and destructive quasistatic tests run in 10° flexion with 7° or 16° varus specimen inclination.
Initial axial stiffness was significantly higher for BDSF in comparison with CFIX at 7° inclination (p=0.02) and not significantly different between BDSF and CFIX at 16° inclination. Compared with the intact state, it decreased significantly at 7° inclination only for CFIX (p=0.01), but not for BDSF. Interfragmentary displacement during cyclic testing was significantly smaller for BDSF than CFIX at 7° inclination (p≤0.04) and not significantly different between BDSF and CFIX at 16° inclination. Failure load did not differ significantly between BDSF and CFIX at both inclinations.
Femoral neck fracture stability can be substantially increased applying BDSF due to better cortical screw support and screw orientation. Having two calcar-buttressed screws oriented in different inclinations, BDSF can enhance constant stability during various patient activities. The more unstable the situation, the better BDSF stability is in comparison to CFIX.
股骨颈骨折的骨合成与20%至46%的并发症发生率相关。自2007年以来，菲利波夫的新型双平面双支撑螺钉固定（BDSF）方法，即使用三根空心螺钉，已显示出优异的临床效果。其两根股骨距支撑螺钉在不同的冠状倾斜度上与骨干轴线成更陡的角度，旨在在不同的负荷情况下提供恒定的固定强度。本研究的目的是对BDSF固定强度进行生物力学评估，并将其与使用三根平行空心螺钉的传统固定（CFIX）进行比较。
对八对新鲜冷冻和六对防腐处理的人体股骨施加CFIX或BDSF，模拟AO/OTA31 - B2.2骨折进行固定。在前 - 后（AP）弯曲中进行准静态测试，然后在标本倾斜7°或16°、屈曲10°的情况下进行轴向准静态、循环和破坏性准静态测试。
在7°倾斜度下，BDSF的初始轴向刚度与CFIX相比显著更高（p = 0.02），在16°倾斜度下，BDSF与CFIX之间无显著差异。与完整状态相比，仅CFIX在7°倾斜度下显著降低（p = 0.01），而BDSF未降低。在7°倾斜度下，循环测试期间的骨折块间位移BDSF比CFIX显著更小（p≤0.04），在16°倾斜度下，BDSF与CFIX之间无显著差异。在两种倾斜度下，BDSF和CFIX的破坏载荷均无显著差异。
由于更好的皮质螺钉支撑和螺钉方向，应用BDSF可显著提高股骨颈骨折的稳定性。BDSF有两根以不同倾斜度定向的股骨距支撑螺钉，可在患者的各种活动中增强恒定稳定性。情况越不稳定，与CFIX相比，BDSF的稳定性越好。
