Biomechanical simulation of radial head subluxation in cadaveric pediatric elbows.

Molly Meadows, Brian Vuong, Hunter Storaci, Kaysie Tam, Kevin Shea
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引用次数: 0

Abstract

Background: Radial head subluxation, known as pulled elbow or nursemaid's elbow, is a common pediatric condition that occurs when a longitudinal traction force is applied to an extended elbow. The purpose of our study was to demonstrate and quantify the axial traction force required to produce a nursemaid's elbow in a pediatric cadaver specimen and to review the current relevant literature.

Methods: We performed a literature search to identify relevant articles describing the nursemaid's elbow injury, as well as relevant biomechanical studies of the radiocapitellar joint. For the biomechanical model, 2 fresh-frozen cadaveric elbows from a single 3-year-old male donor were dissected by a fellowship-trained orthopedic surgeon. An Instron 5,944 testing machine with a 2 kN load cell was used to perform uniaxial testing. The radius and humerus were mounted to the Instron machine and loaded in the axial direction with the elbow in full extension. Loading occurred at a rate of 10 mm/second for 4 seconds, during which the force and actuator displacement were continuously recorded. The local instantaneous load and extension displacement at the time of subluxation were recorded.

Results: The load to failure required to produce the nursemaid's elbow injury in our first specimen was 31 N, with a failure displacement of 4.6 mm. The second specimen demonstrated a load to failure of 26 N, with a failure displacement of 4.6 mm. After subluxation, we reduced the annular ligament from the first specimen. The elbow was then retested and demonstrated a load to failure of 20 N, with a failure displacement of 2.6 mm.

Conclusions: Axial traction applied to a pediatric elbow results in subluxation of the annular ligament into the radiocapitellar joint, at relatively low loads. We demonstrated a mean load to failure in a pediatric cadaveric model of 28.5 N, and a lower load to failure was required to produce a recurrent subluxation in a previously injured specimen.

Key concepts: (1)Radial head subluxation, known as pulled elbow or nursemaid's elbow, is a common pediatric condition that occurs when a longitudinal traction force is applied to an extended elbow.(2)This study is the first to demonstrate and quantify the axial traction force required to produce a nursemaid's elbow in a pediatric cadaver specimen.(3)Axial traction applied to a pediatric cadaver specimen results in subluxation of the annular ligament into the radiocapitellar joint.(4)The mean load to failure is 28.5 N, and a lower load to failure is required to produce a recurrent subluxation in a previously injured specimen.(5)Literature supports that the nursemaid's elbow injury is a result of subluxation of the annular ligament into the radiocapitellar joint, though this may involve a spectrum of injury to the annular ligament itself.

儿童尸体肘部桡骨头半脱位的生物力学模拟。
背景:桡骨头半脱位,被称为牵拉肘或护士肘,是一种常见的儿科疾病,当纵向牵引力作用于伸直的肘时发生。我们研究的目的是证明和量化在儿童尸体标本中产生保姆肘部所需的轴向牵引力,并回顾当前的相关文献。方法:我们进行文献检索,找出描述护士肘部损伤的相关文章,以及桡肱关节的相关生物力学研究。为了建立生物力学模型,一名接受过培训的骨科医生解剖了一名3岁男性供体的2个新鲜冷冻尸体肘部。采用Instron 5944试验机进行单轴测试,该试验机带有2kn称重传感器。桡骨和肱骨安装在Instron机器上,肘关节完全伸展,沿轴向加载。加载速度为10mm /s,加载时间为4秒,加载过程中力和驱动器位移被连续记录。记录半脱位时的局部瞬时载荷和延伸位移。结果:在我们的第一个样本中,产生护士肘关节损伤所需的失效载荷为31 N,失效位移为4.6 mm。第二个试件的破坏荷载为26牛,破坏位移为4.6毫米。半脱位后,我们将第一个标本的环状韧带复位。然后对肘关节进行了重新测试,并证明了20 N的载荷失效,失效位移为2.6 mm。结论:在相对较低的载荷下,对儿童肘关节进行轴向牵引可导致环状韧带半脱位进入肱桡关节。我们在儿童尸体模型中证明了28.5 N的平均负荷失效,而在先前受伤的标本中产生复发性半脱位需要更低的负荷失效。关键概念:(1)桡骨头半脱位,称为牵拉肘或护士肘;(2)本研究首次证明并量化了在儿童尸体标本中产生护士肘所需的轴向牵引力。(3)对儿童尸体标本施加轴向牵引力导致环状韧带半脱位进入肱桡关节。(4)平均载荷为28.5 N。在先前受伤的标本中,产生复发性半脱位需要较低的失败负荷。(5)文献支持护士肘关节损伤是环状韧带半脱位进入肱桡关节的结果,尽管这可能涉及环状韧带本身的一系列损伤。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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