模拟术后加载后采用锁定掌侧钢板治疗的桡骨远端骨折模型中的损伤情况。
Damage in a Distal Radius Fracture Model Treated With Locked Volar Plating After Simulated Postoperative Loading.
作者信息
Salas Christina, Brantley Justin A, Clark James, Reda Taha Mahmoud, Myers Orrin B, Mercer Deana
机构信息
Department of Orthopaedics and Rehabilitation, University of New Mexico, Albuquerque, NM; Department of Mechanical Engineering, University of New Mexico, Albuquerque, NM; Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM.
Department of Orthopaedics and Rehabilitation, University of New Mexico, Albuquerque, NM; Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM.
出版信息
J Hand Surg Am. 2018 Jul;43(7):679.e1-679.e6. doi: 10.1016/j.jhsa.2017.12.019. Epub 2018 Feb 6.
PURPOSE
"Damage" is an engineering term defining a period between a state of material perfection and the onset of crack initiation. Clinically, it is a loss of fixation due to microstructural breakdown, indirectly measured as a reduction of stiffness of the bone-implant construct, normalized by the cross-sectional area and length of the bone. The purpose of this study was to characterize damage in a cadaver model of extra-articular distal radius fracture with dorsal comminution treated using 2-column volar distal radius plates.
METHODS
Ten matched distal radii were randomly divided into 2 groups: group I specimens were treated with a volar distal radius plate with an independent, 2-tiered scaffold design; group II specimens (contralateral limbs) were treated with a volar plate with a single-head design for enhanced ulnar buttressing. Specimens were cyclically loaded to simulate a 6-month postoperative load-bearing period. We report damage after a defined protocol of cyclical loading and load to failure simulating a fall on an outstretched hand.
RESULTS
Group II specimens experienced more damage under cyclic loading conditions than group I specimens. Group I specimens were stiffer than group II specimens under load-to-failure conditions. Ultimate force at failure in group I and group II specimens was not different. Specimens failed by plate bending (group I, n = 6/10; group II, n = 2/10) and fracture of the lunate facet (group I, n = 4/10; group II, n = 8/10).
CONCLUSIONS
Group I specimens had less screw cutout at the lunate facet than group II specimens under cyclic loading as indicated by lower damage measures and fewer facet fractures during load-to-failure testing. The overall strength of the construct is not affected by plate design.
CLINICAL RELEVANCE
Microstructural damage or a loss of fixation due to an overly rigid volar plate design may cause malunion or nonunion of fracture fragments and lead to bone-implant instability.
目的
“损伤”是一个工程学术语，用于定义材料从完美状态到开始出现裂纹之间的时间段。在临床上，它是指由于微观结构破坏而导致的固定丧失，可通过骨 - 植入物结构刚度的降低间接测量，该刚度通过骨的横截面积和长度进行归一化处理。本研究的目的是在一个采用双柱掌侧桡骨远端钢板治疗的伴有背侧粉碎的关节外桡骨远端骨折尸体模型中，对损伤情况进行特征描述。
方法
将十对匹配的桡骨远端随机分为两组：第一组标本采用具有独立双层支架设计的掌侧桡骨远端钢板进行治疗；第二组标本（对侧肢体）采用具有单头设计以增强尺侧支撑的掌侧钢板进行治疗。对标本进行循环加载，以模拟术后6个月的负重期。我们报告了在按照规定的循环加载方案以及模拟伸手跌倒时的破坏载荷加载后出现的损伤情况。
结果
在循环加载条件下，第二组标本比第一组标本遭受更多损伤。在破坏载荷条件下，第一组标本比第二组标本更具刚度。第一组和第二组标本破坏时的极限力并无差异。标本的失效方式为钢板弯曲（第一组，n = 6/10；第二组，n = 2/10）和月骨小面骨折（第一组，n = 4/10；第二组，n = 8/10）。
结论
如在破坏载荷测试期间较低的损伤指标和较少的小面骨折所示，在循环加载条件下，第一组标本在月骨小面处的螺钉穿出情况比第二组标本少。结构的整体强度不受钢板设计的影响。
临床意义
由于掌侧钢板设计过于刚性导致的微观结构损伤或固定丧失，可能会导致骨折碎片的畸形愈合或不愈合，并导致骨 - 植入物不稳定。
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