LISS-DF钢板近端螺钉不同固定方式的力学分析

背景：近年来LISS-DF钢板在临床上得到了广泛应用，随访过程出现了近端螺钉松动、退出的现象，这种现象与近端螺钉的单皮质固定是否存在着相关性尚无定论。 目的：探讨LISS-DF钢板近端螺钉单双皮质不同组合方式固定的力学特性。 方法：用185根新鲜羊股骨，造成股骨远端AO33-A3型骨折模型，均采用5孔LISS-DF钢板通过骨折近端螺钉单双皮质不同组合方式固定，分别作拔出、扭转力学实验，寻找理想的固定方式。 结果与结论：骨折远、近端螺钉常规固定4孔，拔出实验显示：骨折近端螺钉第1、3双皮质、2、4双皮质及1、4双皮质固定时，骨折两端的抗拔出力无显著性差异(P > 0.05)。扭转实验显示：第1、3孔、2、4孔和1、4孔双皮质固定时的抗扭矩值大比较接近，其中1、3孔、2、4孔比较，无显著性差异(P > 0.05)，其余各组之间比较差异显著(P < 0.05)。提示，采用相同规格的LISS-DF钢板治疗股骨远端骨折时，骨折近端螺钉第1、3孔或2、4孔双皮质组合方式固定时，骨折两端的钢板螺钉固定强度的平衡性好，同时在对抗扭转和抗拔出方面明显优于其他组合固定方式。

Biomechanical evaluation of different fixation methods using screws and less invasive stabilization system-distal femur plate at proximal fracture

BACKGROUND: In recent years, Less Invasive Stabilization System-distal femur (LISS-DF) plate has been widely used clinically, and proximal screw loosening and withdrawal are observed during follow-up. However, it remains unclear whether there is correlation between this phenomenon and unilateral cortical fixation of proximal screw. OBJECTIVE: To explore the biomechanical effect of LISS-DF by screw fixation with different unilateral or bilateral cortical in proximal distal femoral fracture. METHODS: Of 185 fresh sheep femora, the distal femoral fracture model of AO33-A3 was made. Five-hole LISS-DF plate was used in combination with screws through the fracture of the proximal cortex of unilateral or bilateral cortical fixed. Pulling and torsion tests were performed to identify ideal fixation way. RESULTS AND CONCLUSION: Fracture distal and proximal screws were used for 4-hole conventional fixation. Pull out experiment showed that there was no significant difference in fracture strength values at both ends of the resistance to pull out in the first 1 and 3 hole fracture of the proximal screws double cortex, 2, 4 and 1, 4 bilateral cortical fixation (P > 0.05). Torsion experiment showed that when the holes of 1 and 3, 2 and 4 and 1 and 4 were fixed, the anti-torque values were similar, and no differences were observed between 1-3 and 2-4 holes (P > 0.05), but differences were observed among other groups (P < 0.05). Results show that when using the same specification LISS-DF plate in the treatment of distal femoral fractures, the 1, 3 holes or 2, 4 holes bilateral cortical fixation displayed good fixation strength of the balance between plate and screw, and better resistance against torsion and pulling out compared with other fixation methods.