Augat P, Bühren V
Institut für Biomechanik, Berufsgenossenschaftliche Unfallklinik Murnau, Prof.-Küntscher-Str. 8, 82418, Murnau, Deutschland,
Unfallchirurg. 2015 Apr;118(4):311-7. doi: 10.1007/s00113-014-2671-7.
Osteosynthesis of distal tibia fractures relies on stable fixation of the distal fragment. Modern intramedullary implants provide various fixation options for locking screws. These implants expand the indications for intramedullary nailing of tibia fractures towards more distally located fractures.
The most essential options which improve the fixation of the distal fragment include an increase in number, in size and in spacing of the distal locking screws. Further options for nailing of distal tibia fractures include interfragmentary compression and angular stability. Interfragmentary compression considerably increases mechanical stability in axially stable fracture situations. Angular stable fixation of the locking screws has recently become a popular feature in intramedullary nailing; however, the effect of angular stability on the mechanical properties of distal tibia osteosynthesis has been found to be limited.
The initial stability to provide sufficient load bearing capacity appears to be provided by the available locking options. With at least two screws, preferably in crossed configuration and spaced over the largest available distance of the distal fragment, secure and stable fixation can be achieved. Insertion of the locking screws in a free hand technique typically results in jamming of the locking screw with the nail and with cortical bone, providing inherent angular stability of the construct. Angular stable locking features of the nail itself do not appear to improve mechanical stability or to affect healing of distal tibia fractures.
胫骨远端骨折的接骨术依赖于远端骨折块的稳定固定。现代髓内植入物为锁定螺钉提供了多种固定选择。这些植入物将胫骨骨折髓内钉固定的适应症扩展到更靠近远端的骨折。
改善远端骨折块固定的最基本选择包括增加远端锁定螺钉的数量、尺寸和间距。胫骨远端骨折的其他钉固定选择包括骨折块间加压和角度稳定性。在轴向稳定的骨折情况下，骨折块间加压可显著提高机械稳定性。锁定螺钉的角度稳定固定最近已成为髓内钉固定的一个常见特点；然而，已发现角度稳定性对胫骨远端接骨术力学性能的影响有限。
现有的锁定选择似乎能提供足够承载能力所需的初始稳定性。至少使用两颗螺钉，最好呈交叉配置并分布在远端骨折块的最大可用距离上，即可实现牢固稳定的固定。徒手技术插入锁定螺钉通常会导致锁定螺钉与髓内钉及皮质骨卡紧，从而为结构提供内在的角度稳定性。髓内钉本身的角度稳定锁定特点似乎并未改善机械稳定性，也未影响胫骨远端骨折的愈合。
