Döbele Stefan, Gardner Michael, Schröter Steffen, Höntzsch Dankward, Stöckle Ulrich, Freude Thomas
BG Trauma Center, Eberhard Karls Universitaet Tuebingen, Tübingen, Germany.
Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri, United States of America.
PLoS One. 2014 Apr 10;9(4):e91933. doi: 10.1371/journal.pone.0091933. eCollection 2014.
Indirect reduction of dia-/metaphyseal fractures with minimally invasive implant application bridges the fracture zone in order to protect the soft-tissue and blood supply. The goal of this fixation strategy is to allow stable motion at the fracture site to achieve indirect bone healing with callus formation. However, concerns have arisen that the high axial stiffness and eccentric position of locked plating constructs may suppress interfragmentary motion and callus formation, particularly under the plate. The reason for this is an asymmetric fracture movement. The biological need for sufficient callus formation and secondary bone healing is three-dimensional micro movement in the fracture zone. The DLS was designed to allow for increased fracture site motion. The purpose of the current study was to determine the biomechanical effect of the DLS_5.0.
Twelve surrogate bone models were used for analyzing the characteristics of the DLS_5.0. The axial stiffness and the interfragmentary motion of locked plating constructs with DLS were compared to conventional constructs with Locking Head Screws (LS_5.0). A quasi-static axial load of 0 to 2.5 kN was applied. Relative motion was measured.
The dynamic system showed a biphasic axial stiffness distribution and provided a significant reduction of the initial axial stiffness of 74.4%. Additionally, the interfragmentary motion at the near cortex increased significantly from 0.033 mm to 0.210 mm (at 200N).
The DLS may ultimately be an improvement over the angular stable plate osteosynthesis. The advantages of the angular stability are not only preserved but even supplemented by a dynamic element which leads to homogenous fracture movement and to a potentially uniform callus distribution.
通过微创植入物应用间接复位骨干/干骺端骨折可跨越骨折区域，以保护软组织和血供。这种固定策略的目标是允许骨折部位进行稳定运动，以实现伴有骨痂形成的间接骨愈合。然而，有人担心锁定钢板结构的高轴向刚度和偏心位置可能会抑制骨折块间的运动和骨痂形成，尤其是在钢板下方。原因是骨折运动不对称。骨折区域充分的骨痂形成和二期骨愈合的生物学需求是三维微运动。动态锁定系统（DLS）的设计旨在增加骨折部位的运动。本研究的目的是确定DLS_5.0的生物力学效应。
使用12个替代骨模型分析DLS_5.0的特性。将采用DLS的锁定钢板结构的轴向刚度和骨折块间运动与采用锁定头螺钉（LS_5.0）的传统结构进行比较。施加0至2.5 kN的准静态轴向载荷。测量相对运动。
动态系统显示出双相轴向刚度分布，并使初始轴向刚度显著降低了74.4%。此外，近皮质处的骨折块间运动从0.毫米显著增加到0.210毫米（在200 N时）。
DLS最终可能是对角度稳定钢板接骨术的一种改进。角度稳定性的优点不仅得以保留，甚至还通过一个动态元件得到补充，该元件导致骨折均匀运动并可能使骨痂分布均匀。
