Timely fracture-healing requires optimization of axial fixation stability
Timely fracture-healing requires optimization of axial fixation stability
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DOI：
10.2106/jbjs.f.00247
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发表时间：
2007-07-01
影响因子：
5.3
通讯作者：
Duda, Georg N.
中科院分区：
文献类型：
--
作者：
Epari, Devakara R.;Kassi, Jean-Pierre;Duda, Georg N.
背景：已知骨愈合对固定的机械稳定性敏感。然而，固定刚度对单个组件愈合的影响仍不清楚。本研究的目的是研究初始体外固定刚度与9周后骨痂强度和刚度之间的关系。我们假设，轴向刚度将确定愈合outcome.Methods：一个标准化的右胫骨中段截骨的美利奴混合羊进行，并与四个单侧外固定器或两个胫骨钉之一，没有铰孔插入稳定。在6种载荷条件（轴向压缩、扭转以及前后和内外侧平面的弯曲和剪切）下，测定绵羊胫骨样本的体外固定刚度。通过将骨折碎片的位移（通过连接的光学标记确定）与材料试验机施加的载荷相关联来计算刚度。扭转测试，直到失败的restricted tibrides进行了9周的愈合后，使用一个标准的材料测试机，以确定失败的时刻和扭转刚度的愈合tibials.Results：羊的外固定通常导致更高的固定刚度比传统的非扩髓胫骨钉。在胫骨髓内钉中使用角度稳定的锁定螺钉导致的固定刚度与外固定相当。具有中等轴向刚度和高剪切刚度的外固定器观察到最高的破坏扭矩。具有最高轴向稳定性的固定器不会导致最高失效力矩。低轴向稳定性与低剪切稳定性相结合，导致在最低的failure moment.Conclusions：在这项研究中，固定的稳定性和愈合胫骨的机械强度之间的关系是明确的。中等水平的轴向稳定性与最高的骨痂强度和刚度相关。
Background: Bone-healing is known to be sensitive to the mechanical stability of fixation. However, the influence on healing of the individual components of fixation stiffness remains unclear. The aim of this study was to investigate the relationship between the initial in vitro fixation stiffness and the strength and stiffness of the callus after nine weeks. We hypothesized that axial stiffness would determine the healing outcome.Methods: A standardized midshaft osteotomy of the right tibia was performed on Merino-mix sheep and was stabilized with either one of four monolateral external fixators or one of two tibial nails inserted without reaming. The in vitro stiffness of fixation was determined in six loading conditions (axial compression, torsion, as well as bending and shear in the anteroposterior and mediolateral planes) on ovine tibial specimens. Stiffness was calculated by relating displacements of the fracture fragments, determined by means of attached optical markers, and the loads applied by a materials testing machine. Torsional testing until failure of the explanted tibiae was performed with use of a standard materials testing machine after nine weeks of healing to determine the failure moment and the torsional stiffness of the healed tibia.Results: External fixation in sheep generally resulted in higher fixation stiffness than did conventional unreamed tibial nailing. The use of angle-stable locking screws in tibial nailing resulted in fixation stiffness comparable with that of external fixation. The highest torsional moment to failure was observed for the external fixator with moderate axial stiffness and high shear stiffness. The fixator with the highest axial stability did not result in the highest failure moment. Low axial stability in combination with low shear stability resulted in the lowest failure moment.Conclusions: In this study, a clear relationship between the stability of fixation and the mechanical strength of the healing tibia was seen. Moderate levels of axial stability were associated with the highest callus strength and stiffness.