Lewis Ryan A, Lewis Daniel D, Anderson Christopher L, Hudson Caleb C, Coggeshall Jason D, Iorgulescu Alex D, Banks Scott A
Comparative Orthopaedics and Biomechanics Laboratory, University of Florida, Gainesville, Florida.
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida.
Vet Surg. 2016 May;45(4):471-9. doi: 10.1111/vsu.12467. Epub 2016 Mar 24.
Evaluate the effects of supplemental fixation elements on the mechanical properties of a single ring circular fixator construct.
In vitro mechanical testing.
Five construct configurations (six replicates of each configuration) were used to stabilize a 1.6 cm diameter Delrin rod bone model.
Constructs were assembled using 66 mm complete rings, 1.6 mm olive wires, and 3.2 mm diameter half-pins. Construct configurations tested were a base single ring construct, constructs with 1 supplemental drop wire or constructs with 1, 2, or 3 supplemental half-pins. Constructs were loaded in axial compression, caudocranial and mediolateral bending, and torsion. Strain was measured in individual fixation elements during axial loading.
A supplemental drop wire or half-pin significantly increased bending and torsional stiffness. The supplemental half-pin increased caudocranial stiffness significantly more than placing a drop wire. Placing a 2nd or 3rd pin afforded significantly greater increases in construct stiffness in all modes of loading, with 3 half-pin constructs having significantly greater axial and caudocranial stiffness than 2 half-pin constructs. Placing a single supplemental pin induced cantilever bending resulting in angular displacement of the Delrin rod during axial loading and high strain in both the fixation wire secured distal to the ring and the pin. Supplemental half-pins incrementally reduced strain in all fixation elements and resulted in linear displacement of the Delrin rod during axial loading.
If using supplemental half-pins as fixation elements, insertion of 2 or 3 pins is preferred over a single pin.
评估附加固定元件对单环环形固定器结构力学性能的影响。
体外力学测试。
使用五种结构配置（每种配置六个重复样本）来稳定一个直径1.6厘米的聚甲醛棒骨模型。
使用66毫米完整环、1.6毫米橄榄丝和直径3.2毫米的半针组装结构。测试的结构配置包括一个基础单环结构、带有1根附加吊线的结构或带有1、2或3根附加半针的结构。对结构进行轴向压缩、尾颅侧和内外侧弯曲以及扭转加载。在轴向加载过程中测量各个固定元件的应变。
附加吊线或半针显著提高了弯曲和扭转刚度。附加半针比放置吊线更显著地增加了尾颅侧刚度。放置第二根或第三根半针在所有加载模式下都能显著提高结构刚度，三根半针结构的轴向和尾颅侧刚度显著大于两根半针结构。放置一根附加半针会引起悬臂弯曲，导致聚甲醛棒在轴向加载过程中发生角位移，并且在环远端固定的固定丝和半针中产生高应变。附加半针逐渐降低了所有固定元件中的应变，并导致聚甲醛棒在轴向加载过程中发生线性位移。
如果使用附加半针作为固定元件，插入2根或3根半针比插入1根半针更可取。
