Rawlings Mathew, Knox David, Patel Minoo, Ackland David
Department of Mechanical Engineering, University of Melbourne, Parkville, Victoria 3010, Australia.
Department of Orthopaedic Surgery, Epworth Healthcare, Richmond, Victoria 3121, Australia; Centre for Limb Reconstruction, The Epworth Centre, Richmond, Victoria 3121, Australia.
Injury. 2016 Apr;47(4):893-8. doi: 10.1016/j.injury.2016.01.042. Epub 2016 Feb 8.
The purpose of this study was to demonstrate the strength characteristics of a hybrid uni-cortical construct for clavicle fixation. The technique reported aims to combine benefits of uni-cortical fixation with stability comparable to traditional bi-cortical fixation. The approach utilises long, oblique uni-cortical screws at the distal ends of the plate acting as surrogate bi-cortical screws. Locked uni-cortical screws positioned centrally provide bending and torsion strength to the construct. This alternative hybrid uni-cortical technique does not require far cortex screw or drill penetration required in bi-cortical fixation techniques, thus avoiding potentially catastrophic vascular and or neurologic injury. The purpose of this study was to compare the mechanical behaviour of the hybrid uni-cortical construct to standard bi-cortical fixations under both torsion and bending loads.
Thirty osteotomized human cadaveric clavicles were randomly allocated to three surgical fixation techniques: bi-cortical locked screw fixation, bi-cortical non-locked screw fixation and hybrid uni-cortical screw fixation. Each clavicle construct was tested non-destructively under torsional loading, and then under cantilever bending to failure. Construct bending and torsional stiffness, as well as ultimate failure strength, were measured.
There were no significant differences between uni-cortical or bi-cortical fixation constructs in either bending stiffness or ultimate bending moment (p>0.05); however, there was a trend towards greater bending stiffness in the hybrid construct. The uni-cortical hybrid fixation technique displayed a significantly lower mean torsional stiffness value when compared with the bi-cortical locked screw fixation (mean difference: 134.4 Nmm/degrees, 95% confidence interval [32.3, 236.4], p=0.007).
A hybrid uni-cortical approach to clavicle plate fixation that may improve screw purchase and reduce risk of intra-operative vascular damage demonstrates comparable bending strength to current bi-cortical approaches.
本研究的目的是展示一种用于锁骨固定的混合单皮质结构的强度特性。所报道的技术旨在将单皮质固定的优点与可媲美传统双皮质固定的稳定性相结合。该方法利用钢板远端的长斜单皮质螺钉作为替代双皮质螺钉。位于中心位置的锁定单皮质螺钉为该结构提供弯曲和扭转强度。这种替代性的混合单皮质技术不需要双皮质固定技术中所需的远皮质螺钉或钻孔穿透，从而避免了潜在的灾难性血管和/或神经损伤。本研究的目的是比较混合单皮质结构与标准双皮质固定在扭转和弯曲载荷下的力学行为。
将30根截骨的人尸体锁骨随机分配到三种手术固定技术中：双皮质锁定螺钉固定、双皮质非锁定螺钉固定和混合单皮质螺钉固定。每个锁骨结构先在扭转载荷下进行无损测试，然后在悬臂弯曲至破坏的情况下进行测试。测量结构的弯曲和扭转刚度以及极限破坏强度。
单皮质或双皮质固定结构在弯曲刚度或极限弯矩方面均无显著差异（p>0.05）；然而，混合结构有更高弯曲刚度的趋势。与双皮质锁定螺钉固定相比，单皮质混合固定技术的平均扭转刚度值显著更低（平均差异：134.4 Nmm/度，95%置信区间[32.3, 236.4]，p = 0.007）。
一种用于锁骨钢板固定的混合单皮质方法，可能改善螺钉固定并降低术中血管损伤风险，其弯曲强度与当前双皮质方法相当。
