Claes L, Hutzschenreuter P
Z Orthop Ihre Grenzgeb. 1975 Apr;113(2):237-42.
For the better understanding of fracture fixation by means of screws the torque load and types of fractures from threaded screw holes in cortical bone were studied. The experiments were performed on sheep tibia and femora in vitro and in vivo. We applied the 4.5 mm cortical bone screw (AISF) as lag screw. The screw was threaded in until total destruction of the thread occurred. The process of torque load was registered as a torque-angle of twist curve with 4 typical parts. Histologically in most cases shear fractures with different geometry occurred. In some cases we found conical geometric, and in others cylindrical geometric fragments in the threaded screw holes. The value of the torque at which destruction of a threaded hole occurs is a linear function of the thickness of the cortical bone. The gradient of this linear function is 6.6 kpcm/mm. In practical case, the insertional torque may be estimated by multiplying the cortical bone thickness in mm (if known) by a factor 4.
为了更好地理解通过螺钉进行骨折固定，研究了皮质骨螺纹螺孔的扭矩负荷和骨折类型。实验在绵羊胫骨和股骨上进行，包括体外和体内实验。我们使用4.5毫米皮质骨螺钉（AISF）作为拉力螺钉。将螺钉拧入直至螺纹完全破坏。扭矩加载过程记录为具有4个典型部分的扭矩-扭转角度曲线。组织学上，大多数情况下会出现不同几何形状的剪切骨折。在某些情况下，我们在螺纹螺孔中发现了圆锥形几何形状的碎片，而在其他情况下则发现了圆柱形几何形状的碎片。螺纹孔发生破坏时的扭矩值是皮质骨厚度的线性函数。该线性函数的梯度为6.6 kpcm/mm。在实际情况中，插入扭矩可通过将以毫米为单位的皮质骨厚度（如果已知）乘以系数4来估算。
