*Institute of Biomechanics, Trauma Center Murnau, Murnau, Germany and Paracelsus Medical University, Salzburg, Austria; and ‡Stryker Osteosynthesis, Biomechanics Groups, Schönkirchen, Germany and Selzach, Switzerland.
J Orthop Trauma. 2014 Mar;28(3):130-6. doi: 10.1097/BOT.0b013e31829d19a4.
The investigation hypothesized that in current anatomical precontoured plates, angular stability plays only a minor role for the efficacy of the osteosynthesis at the distal humerus.
An AO C2.3 fracture model was simulated and osteosynthesis performed with plates positioned in parallel. System rigidity and median fatigue limit were analyzed in artificial bones and the cycles to failure in cadaver specimens. Loads were applied in anterior-posterior direction (75° flexion) and axial direction (5° flexion). Four composite bone groups were investigated as follows: (1) 2.7 mm polyaxial locking screws, (2) 3.5 mm polyaxial locking screws, (3) 3.5 mm polyaxial locking screws and a gap bridging screw, and (4) 2.7 mm nonlocking screws. Two cadaver groups were investigated with 3.5 mm diameter polyaxial locking (5) versus nonlocking screws (6).
There were no differences in stiffness found between the locking versus nonlocking constructs in artificial (1) versus (4) and in cadaver bones (5) versus (6). The larger screw diameter of 3.5 mm in combination with a gap bridging screw significantly increased construct stiffness by 25% (3). The median fatigue limit was significantly increased using larger screw diameters (2) and a gap bridging screw (3). In cadaver bones, the polyaxial locking screws constructs (5) resisted higher peak loads and more cycles until failure compared with nonlocking constructs (6).
System stiffness increases with larger screw diameters and becomes significant with additional gap bridging screws in artificial bones. The use of polyaxial locking screws in anatomical adapted plates becomes more important in poor bone quality.
本研究假设在当前解剖预成型的接骨板中，角度稳定性对于肱骨远端接骨板固定的疗效仅起次要作用。
模拟 AO C2.3 骨折模型，采用平行定位的接骨板进行接骨。在人工骨中分析系统刚性和中位疲劳极限，并在尸体标本中分析失效循环。在 75°屈曲的前-后方向和 5°屈曲的轴向方向上施加负荷。共研究了 4 组复合骨，具体如下：（1）2.7mm 多轴锁定螺钉，（2）3.5mm 多轴锁定螺钉，（3）3.5mm 多轴锁定螺钉和桥接间隙螺钉，以及（4）2.7mm 非锁定螺钉。还研究了 2 组尸体，使用 3.5mm 直径的多轴锁定螺钉（5）与非锁定螺钉（6）。
在人工骨中（1）与（4）以及尸体骨中（5）与（6），锁定与非锁定结构之间的刚度没有差异。更大直径的 3.5mm 螺钉与桥接间隙螺钉结合可使结构刚度显著增加 25%（3）。更大直径的螺钉（2）和桥接间隙螺钉（3）可显著提高中位疲劳极限。与非锁定结构（6）相比，多轴锁定螺钉结构（5）在尸体骨中能抵抗更高的峰值负荷和更多的失效循环。
在人工骨中，系统刚度随更大直径的螺钉而增加，并且随着附加的桥接间隙螺钉而变得显著。在骨质量较差的情况下，在解剖适配的接骨板中使用多轴锁定螺钉变得更为重要。
