Norwegian Orthopaedic Implant Research Unit, NKSOI, Orthopaedic Department, Bevegelsessenteret, St. Olavs Hospital, Trondheim University Hospital, 7006 Trondheim, Norway.
J Biomech. 2011 May 17;44(8):1454-8. doi: 10.1016/j.jbiomech.2011.03.018. Epub 2011 Mar 30.
Small diameter transosseous wires are main parts of the Ilizarov frame concept. Wire tensioning is essential to gain the necessary transversal stiffness, and the wire fixators are therefore important, coupling the wire to the ring. The ability of three different wire fixator designs to maintain wire tension under dynamic loading is described. The three fixator designs were combinations of two types of bolts and one washer. In a simplified frame set-up consisting of one ring and one wire, sixty wires were dynamically loaded in sequence with 200N for 450 times and wire tension was repeatedly measured. The tension loss employing the different fixator types at two wire pretension levels (883N, 1275N) was measured. Wire slippage in the fixators and the midpoint deflection angle of the wires were measured. Large differences in fixation ability were observed. Wire fixators holding a larger and rougher contact surface had significant smaller tension loss compared to fixators with a smaller and smother contact surface. Both plastic wire deformation and slippage causes tension loss with slippage as the main contributor. Wire fixators' design can be improved in order to maintain wire tension. Such improvement could be of clinical interest enhancing the mechanical stability of the fixator.
小直径贯穿骨钢丝是伊利扎洛夫框架概念的主要部分。钢丝张紧对于获得必要的横向刚度至关重要，因此钢丝固定器非常重要，它将钢丝与环连接起来。描述了三种不同的钢丝固定器设计在动态负载下保持钢丝张力的能力。这三种固定器设计是两种类型的螺栓和一种垫圈的组合。在一个简化的框架设置中，由一个环和一根钢丝组成，六十根钢丝被依次动态加载 200N 450 次，并反复测量钢丝张力。在两种钢丝预紧水平（883N，1275N）下测量了不同固定器类型的张力损失。测量了钢丝在固定器中的滑动和钢丝中点挠度角。观察到固定能力存在很大差异。与具有较小和较光滑接触表面的固定器相比，具有较大和较粗糙接触表面的固定器的张力损失明显较小。钢丝的塑性变形和滑动都会导致张力损失，而滑动是主要原因。为了保持钢丝张力，可以改进钢丝固定器的设计。这种改进可能会引起临床关注，增强固定器的机械稳定性。
