Biomechanical comparison of three internal fixation configurations for low transcondylar fractures of the distal humerus

BackgroundWe aimed to evaluate the biomechanical stiffness and strength of different internal fixation configurations and find suitable treatment strategies for low transcondylar fractures of the distal humerus.Methods and materialsThirty 4^th generation composite humeri were used to create low transcondylar fracture models that were fixed by orthogonal and parallel double plates as well as posterolateral plate and medial screw (PPMS) configurations (n=10 in each group) using an anatomical locking compression plate-screw system and fully threaded medial cortical screws. Posterior bending (maximum 50 N), axial loading (maximum 200 N) and internal rotation (maximum 10 N·m) were tested, in that order, for each specimen. Stiffness under different biomechanical settings among different configurations were compared. Another 18 sets of fracture models were created using these three configurations (n=6 in each group) and the load to failure under axial loading among different configurations was compared.ResultsUnder posterior bending, the stiffness of parallel group was higher than orthogonal group (P<0.001), and orthogonal group was higher than PPMS group (P<0.001). Under axial loading, the stiffness of parallel group was higher than orthogonal group (P=0.001) and PPMS group (P<0.001); however, the difference between orthogonal and PPMS group was not statistically significant (P>0.05). Under internal rotation, the stiffness of parallel group was higher than orthogonal group (P=0.044), and orthogonal group was higher than PPMS group (P=0.029). In failure test under axial loading, the load to failure in the orthogonal group was lower than parallel group (P=0.009) and PPMS group (P=0.021), but the difference between parallel group and PPMS group was not statistically significant (P>0.05). All specimens in orthogonal group demonstrated “distal medial failure”; most specimens had “distal medial and trochlear failure” in the parallel group; most specimens exhibited “contact failure” in the PPMS group.ConclusionFor treating low transcondylar fractures, the overall stiffness and strength of the parallel configuration were superior to those of the orthogonal and PPMS configurations. Nevertheless, the PPMS configuration can provide adequate stability and stiffness comparable to double-plate configurations under axial loading. Therefore, the PPMS construct may have certain clinical value.     

海螵蛸对骨愈合相关基因表达的影响

为揭示中药海螵蛸在骨折愈合过程中的干预作用,了解海螵蛸的调节靶点,探索建构中药基因组学的途径.通过在大鼠胫骨打孔的方法建立单因素干扰模型,在不同时间点采用原位杂交方法对各类mRNA的变化进行动态观察骨愈合过程中Ⅰ、Ⅱ、Ⅲ型前胶原mRNA、转化生长因子(TGG)-β1 mRNA、骨形态发生蛋白(BMP)-2mRNA、血管内皮生长因子(VEGF) mRNA表达情况.结果显示,海螵蛸在骨折早期对Ⅰ、Ⅲ型前胶原mRNA、VEGFmRNA、BMP-2mRNA的表达升高,而对Ⅱ型前胶原mRNA、TGF-β1 mRNA的表达量无明显影响;但达到峰值后,Ⅱ、Ⅲ型前胶原mRNA表达水平下降,VEGFmRNA、TGF-β1mRNA表达量中后期维持于较高水平.表明海螵蛸与血管形成有关,对骨折软骨形成早期具有促进骨诱导的作用,并对成骨细胞的增殖及合成活性有较大影响.     

The 3D-printed patient-specific acetabular component in the management of extensive acetabular defect with combined bilateral pelvic discontuinity

Extensive acetabular defects with combined pelvic discontinuity is a surgical challenge. The ideal treatment choice is not adopted, yet. We here introduce the 3D-printed custom acetabular component in the management of extensive acetabular defect with combined pelvic discontinuity. The article presents the surgical technique and and discuss the advantages and disadvantages of this method. Furthermore, we present a successful treatment of a 64-year old using this construct.