Sod Gary A, Riggs Laura M, Mitchell Colin F, Martin George S, Gill Marjorie S
Equine Health Studies Program, Department of Veterinary Clinical Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, LA 70803, USA.
Vet Surg. 2010 Jul;39(5):581-7. doi: 10.1111/j.1532-950X.2010.00684.x. Epub 2010 May 6.
To compare the monotonic biomechanical properties and fatigue life of a 5.5-mm-broad locking compression plate (5.5 LCP) fixation with a 4.5-mm-broad locking compression plate (4.5 LCP) fixation to repair osteotomized equine 3rd metacarpal (MC3) bones.
In vitro biomechanical testing of paired cadaveric equine MC3 with a middiaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation.
Fifteen pairs of adult equine cadaveric MC3 bones.
Fifteen pairs of equine MC3 were divided into 3 test groups (5 pairs each) for (1) 4-point bending single cycle to failure testing, (2) 4-point bending cyclic fatigue testing, and (3) torsional single cycle to failure testing. An 8-hole, 5.5 LCP was applied to the dorsal surface of 1 randomly selected bone from each pair and an 8-hole, 4.5 LCP was applied dorsally to the contralateral bone from each pair using a combination of cortical and locking screws. All plates and screws were applied using standard ASIF techniques. All MC3 bones had middiaphyseal osteotomies. Mean test variable values for each method were compared using a paired t-test within each group with significance set at P<.05.
Mean yield load, yield bending moment, composite rigidity, failure load, and failure bending moment, under 4-point bending, single cycle to failure, of the 5.5 LCP fixation were significantly greater than those of the 4.5 LCP fixation. Mean cycles to failure in 4-point bending of the 5.5 LCP fixation (170,535+/-19,166) was significantly greater than that of the 4.5 LCP fixation (129,629+/-14,054). Mean yield load, mean composite rigidity, and mean failure load under torsional testing, single cycle to failure was significantly greater for the broad 5.5 LCP fixation compared with the 4.5 LCP fixation. In single cycle to failure under torsion, the mean+/-SD values for the 5.5 LCP and the 4.5 LCP fixation techniques, respectively, were: yield load, 151.4+/-19.6 and 97.6+/-12.1 N m; composite rigidity, 790.3+/-58.1 and 412.3+/-28.1 N m/rad; and failure load: 162.1+/-20.2 and 117.9+/-14.6 N m.
The 5.5 LCP was superior to the 4.5 LCP in resisting static overload forces (palmarodorsal 4-point bending and torsional) and in resisting cyclic fatigue under palmarodorsal 4-point bending.
These in vitro study results may provide information to aid in selection of an LCP for repair of equine long bone fractures.
比较5.5毫米宽锁定加压钢板（5.5 LCP）固定与4.5毫米宽锁定加压钢板（4.5 LCP）固定修复马第三掌骨（MC3）截骨的单调生物力学性能和疲劳寿命。
对成对的尸体马MC3进行体外生物力学测试，采用中骨干截骨术，通过两种骨折固定方法之一进行稳定。
15对成年马尸体MC3骨。
将15对马MC3分为3个测试组（每组5对），分别进行（1）4点弯曲单周期至破坏测试，（2）4点弯曲循环疲劳测试，以及（3）扭转单周期至破坏测试。从每对中随机选择1块骨，在其背侧应用一块8孔5.5 LCP，对每对中的对侧骨背侧应用一块8孔4.5 LCP，使用皮质骨螺钉和锁定螺钉的组合。所有钢板和螺钉均采用标准的ASIF技术应用。所有MC3骨均进行中骨干截骨术。每组内使用配对t检验比较每种方法的平均测试变量值，显著性设定为P<0.05。
在4点弯曲单周期至破坏测试中，5.5 LCP固定的平均屈服载荷、屈服弯矩、复合刚度、破坏载荷和破坏弯矩均显著高于4.5 LCP固定。5.5 LCP固定在4点弯曲中的平均破坏循环次数（170,535±19,166）显著高于4.5 LCP固定（129,629±14,054）。在扭转测试单周期至破坏中，宽5.5 LCP固定的平均屈服载荷、平均复合刚度和平均破坏载荷显著高于4.5 LCP固定。在扭转单周期至破坏中，5.5 LCP和4.5 LCP固定技术的平均±标准差分别为：屈服载荷，151.4±19.6和97.6±12.1 N·m；复合刚度，790.3±58.1和412.3±28.1 N·m/rad；破坏载荷：162.1±20.2和117.9±14.6 N·m。
在抵抗静态过载力（掌背4点弯曲和扭转）以及掌背4点弯曲下的循环疲劳方面，5.5 LCP优于4.5 LCP。
这些体外研究结果可能为选择用于修复马长骨骨折的LCP提供信息。
