Department of Orthopedic Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai 200233, China.
Biomed Res Int. 2019 Jul 7;2019:2584151. doi: 10.1155/2019/2584151. eCollection 2019.
To verify the biomechanical importance with respect to the integrity of posteromedial cortex of femoral neck fracture (FNF) and demonstrate whether the modified fixation of cannulated screws (CSs) could increase the biomechanical strength.
A total of 24 left artificial femurs were randomly divided into three groups. The osteotomy was made in the center of the femoral neck at a 20° angle to the shaft axial. The posteromedial cortices of femoral neck were removed in groups B and C. In group A, 8 femurs with intact posteromedial cortex were fixed with three parallel partial thread screws (PTSs), forming a standard triangle. In group B, the femurs were stabilized with the same fixation of CSs like group A. In group C, two inferior PTSs were replaced by two fully thread screws (FTSs).
The lower A-P and axial stiffness and load to failure along with higher axial displacement were found in group B compared with group A (p≤0.001 for all). Between groups B and C, the modified fixation of CSs increased A-P and axial stiffness and load to failure and reduced the axial displacement (p≤0.001 for all).
We verified that the comminuted posteromedial cortex affected the biomechanical strength adversely and resulted in higher displacement. The modified fixation of CSs characterized by two inferior FTSs could improve the biomechanical performance and buttress the femoral head fragment better.
验证股骨颈骨折（FNF）后柱完整性的生物力学重要性，并证明改良空心螺钉（CSs）固定能否增加生物力学强度。
将 24 个左侧人工股骨随机分为三组。在与骨干轴向成 20°角的中心位置对股骨颈进行截骨。在 B 组和 C 组中去除股骨颈后柱皮质。在 A 组中，8 个完整的股骨颈后柱采用三根平行的部分螺纹螺钉（PTSs）固定，形成标准三角形。在 B 组中，股骨采用与 A 组相同的 CSs 固定。在 C 组中，两根下 PTS 被两根全螺纹螺钉（FTSs）取代。
与 A 组相比，B 组的 A-P 和轴向刚度以及失效时的载荷以及更高的轴向位移降低（所有 p≤0.001）。与 B 组相比，CSs 的改良固定增加了 A-P 和轴向刚度以及失效时的载荷，并降低了轴向位移（所有 p≤0.001）。
我们验证了粉碎性后柱皮质会对生物力学强度产生不利影响，导致更高的位移。由两根下 FTSs 组成的 CSs 改良固定可改善生物力学性能，更好地支撑股骨头碎片。
