AO Research Institute Davos, AO Foundation, Davos, Switzerland.
J Orthop Trauma. 2011 Jun;25(6):340-6. doi: 10.1097/BOT.0b013e3182163345.
To compare mechanical stability of angle-stable locking construct with four screws with conventional five screw locking in intramedullary nailed distal tibia fractures under cyclic loading.
Ten pairs of fresh-frozen human cadaveric tibiae were intramedullary nailed and assigned to either an angle-stable locking construct consisting of four screws or conventional five-screw locking. After simulating an unstable distal two-fragmental 42-A3.1 fracture, the specimens were mechanically tested under quasistatic and cyclic sinusoidal axial and torsional loading.
Bending stiffness of the angle-stable and the conventional fixation was 644.3 N/° and 416.5 N/°, respectively (P = 0.075, power 0.434). Torsional stiffness of the angle-stable locking (1.91 Nm/°) was significantly higher compared with the conventional one (1.13 Nm/°; P = 0.001, power 0.981). Torsional play of the angle-stable fixation (0.08°) was significantly smaller compared with the conventional one (0.46°; P = 0.002, power 0.965). The angle-stable locking revealed significantly less torsional deformation in the fracture gap after one cycle (0.74°) than the conventional one (1.75°; P = 0.005, power 0.915) and also after 1000 cycles (angle-stable: 1.56°; conventional: 2.51°; P = 0.042, power 0.562). Modes of failure were fracture of the distal fragment, loosening of distal locking screws, nail breakage, and their combination, equally distributed between the groups (P = 0.325).
Both the angle-stable locking technique using four screws and conventional locking consisting of five screws showed high biomechanical properties. Hence, angle-stable locking reflects a potential to maintain fixation stability while reducing the number of locking screws compared with conventional locking in intramedullary nailed unstable distal tibia fractures.
比较在循环载荷下，髓内钉固定的胫骨远端不稳定 42-A3.1 骨折中，使用四枚螺钉的角稳定锁定与传统五枚螺钉锁定的机械稳定性。
10 对新鲜冷冻的人尸体胫骨进行髓内钉固定，分为角稳定锁定（由四枚螺钉组成）或传统五螺钉锁定。模拟不稳定的远端双片段 42-A3.1 骨折后，标本在准静态和循环正弦轴向和扭转加载下进行机械测试。
角稳定和传统固定的弯曲刚度分别为 644.3 N/°和 416.5 N/°（P=0.075，功率 0.434）。角稳定锁定的扭转刚度（1.91 Nm/°）明显高于传统固定（1.13 Nm/°；P=0.001，功率 0.981）。角稳定固定的扭转间隙（0.08°）明显小于传统固定（0.46°；P=0.002，功率 0.965）。角稳定锁定在一个循环后（0.74°），骨折间隙的扭转变形明显小于传统固定（1.75°；P=0.005，功率 0.915），在 1000 次循环后（角稳定：1.56°；传统：2.51°；P=0.042，功率 0.562）也是如此。失效模式为远端骨折、远端锁定螺钉松动、钉断裂及其组合，两组分布均匀（P=0.325）。
使用四枚螺钉的角稳定锁定技术和传统的五枚螺钉锁定均表现出较高的生物力学性能。因此，与传统锁定相比，角稳定锁定在髓内钉固定不稳定的胫骨远端骨折中具有维持固定稳定性的潜力，同时减少锁定螺钉的数量。
