Gueorguiev Boyko, Wähnert Dirk, Albrecht Daniel, Ockert Ben, Windolf Markus, Schwieger Karsten
AO Research Institute Davos, AO Foundation, Davos, Switzerland.
J Trauma. 2011 Feb;70(2):358-65. doi: 10.1097/TA.0b013e3181dbaaaf.
Unstable distal tibia fractures are challenging injuries that require surgery. Increasingly, intramedullary nails are being used. However, fracture site anatomy may cause distal-fragment stabilization and fixation problems and lead to malunion/nonunion. We studied the influence of angle-stable nail locking on fracture gap movement and other biomechanical parameters.
Eight pairs of fresh human cadaver tibiae were used. The bone mineral density (BMD) was determined. All tibiae were nailed with a Synthes Expert tibial nail. Within each pair, one tibia was randomized to receive conventional locking screws; the other, angle-stable screws with sleeves. A 7-mm osteotomy was created 10 mm above the upper distal locking screw, to simulate an AO 42-A3 fracture. Biomechanical testing involved nondestructive mediolateral and anteroposterior pure bending, followed by cyclic combined axial and torsional loading to catastrophic failure. The neutral zone was determined. Fracture gap movement was monitored with 3-D motion tracking.
The angle-stable locked constructs had a significantly smaller mediolateral neutral zone (mean: 0.04 degree; p=0.039) and significantly smaller fracture gap angulation (p=0.043). The number of cycles to failure did not differ significantly between the locking configurations. BMD was a significant covariate affecting the number of cycles to failure (p=0.008). However, over the first 20,000 cycles, there was no significant correlation in the angle-stable construct.
Angle-stable locking of the Expert tibial nail was associated with a significant reduction in the mediolateral neutral zone and in fracture gap movement. Angle-stable fixation also reduced the influence of BMD over the first 20,000 cycles.
不稳定的胫骨远端骨折是具有挑战性的损伤，需要进行手术治疗。髓内钉的使用越来越普遍。然而，骨折部位的解剖结构可能导致远端骨折块的稳定和固定问题，并导致畸形愈合/不愈合。我们研究了角度稳定型髓内钉锁定对骨折间隙移动及其他生物力学参数的影响。
使用8对新鲜的人体尸体胫骨。测定骨密度（BMD）。所有胫骨均使用Synthes Expert胫骨钉进行髓内钉固定。在每对胫骨中，随机选择一根胫骨使用传统锁定螺钉；另一根使用带套筒的角度稳定型螺钉。在距远端上方锁定螺钉10 mm处制造一个7-mm的截骨，以模拟AO 42-A3骨折。生物力学测试包括无损的内外侧和前后侧纯弯曲，随后进行循环轴向和扭转加载直至灾难性破坏。确定中性区。使用三维运动跟踪监测骨折间隙移动。
角度稳定锁定结构的内外侧中性区明显更小（平均：0.04度；p = 0.039），骨折间隙成角明显更小（p = 0.043）。两种锁定方式下至破坏的循环次数无显著差异。骨密度是影响至破坏循环次数的显著协变量（p = 0.008）。然而，在最初的20,000次循环中，角度稳定结构中无显著相关性。
Expert胫骨钉的角度稳定锁定与内外侧中性区及骨折间隙移动的显著减少相关。角度稳定固定在最初的20,000次循环中也减少了骨密度的影响。
