Niederhäuser Simone K, Tepic Slobodan, Weber Urs T
Tierärztliches Überweisungszentrum, Small Animal Referral Practice, CH-4456 Tenniken, Switzerland.
Am J Vet Res. 2015 May;76(5):402-10. doi: 10.2460/ajvr.76.5.402.
To evaluate the effect of screw position on strength and stiffness of a combination locking plate-rod construct in a synthetic feline femoral gap model.
30 synthetic long-bone models derived from beechwood and balsa wood.
3 constructs (2 locking plate-rod constructs and 1 locking plate construct; 10 specimens/construct) were tested in a diaphyseal bridge plating configuration by use of 4-point bending and torsion. Variables included screw position (near the fracture gap and far from the fracture gap) and application of an intramedullary pin. Constructs were tested to failure in each loading mode to determine strength and stiffness. Failure was defined as plastic deformation of the plate or breakage of the bone model or plate. Strength, yield angle, and stiffness were compared by use of a Wilcoxon test.
Placement of screws near the fracture gap did not increase bending or torsional stiffness in the locking plate-rod constructs, assuming the plate was placed on the tension side of the bone. Addition of an intramedullary pin resulted in a significant increase in bending strength of the construct. Screw positioning did not have a significant effect on any torsion variables.
Results of this study suggested that, in the investigated plate-rod construct, screw insertion adjacent to the fracture lacked mechanical advantages over screw insertion at the plate ends. For surgeons attempting to minimize soft tissue dissection, the decision to make additional incisions for screw placement should be considered with even more caution.
在合成猫股骨干间隙模型中，评估螺钉位置对锁定钢板 - 棒组合结构强度和刚度的影响。
30个由山毛榉木和轻木制成的合成长骨模型。
采用4点弯曲和扭转试验，对3种结构（2种锁定钢板 - 棒结构和1种锁定钢板结构；每种结构10个样本）进行骨干桥接钢板配置测试。变量包括螺钉位置（靠近骨折间隙和远离骨折间隙）以及髓内针的应用。每种加载模式下对结构进行测试直至破坏，以确定强度和刚度。破坏定义为钢板的塑性变形或骨模型或钢板的断裂。使用Wilcoxon检验比较强度、屈服角和刚度。
假设钢板置于骨的张力侧，在锁定钢板 - 棒结构中，将螺钉置于靠近骨折间隙处并不会增加弯曲或扭转刚度。添加髓内针会使结构的弯曲强度显著增加。螺钉位置对任何扭转变量均无显著影响。
本研究结果表明，在所研究的钢板 - 棒结构中，在骨折处附近插入螺钉相较于在钢板末端插入螺钉缺乏力学优势。对于试图尽量减少软组织剥离的外科医生而言，决定为螺钉置入额外做切口时应更加谨慎。
