Forman Jason, Perry Brandon, Alai Aaron, Freilich Aaron, Salzar Robert, Walilko Tim
From the University of Virginia Center for Applied Biomechanics (J.F.), Charlottesville, Virginia; University of Virginia Center for Applied Biomechanics (B.P.), Charlottesville, Virginia; University of Virginia Center for Applied Biomechanics (A.A.), Charlottesville, Virginia; University of Virginia Department of Orthopaedics (A.F.) and the University of Virginia Hand Center, Charlottesville, Virginia; University of Virginia Center for Applied Biomechanics (R.S.), Charlottesville, Virginia; and Applied Research Associates (T.W.), Littleton, Colorado.
J Trauma Acute Care Surg. 2014 Sep;77(3 Suppl 2):S176-83. doi: 10.1097/TA.0000000000000329.
The wrist/forearm complex is one of the most commonly fractured body regions, yet the impact tolerance of the wrist is poorly understood. This study sought to quantify the injury tolerance of the adult male forearm-wrist complex under loading simulating axial impact to an outstretched hand.
Fifteen isolated cadaveric forearm/wrist specimens were tested. Loading was applied via an instrumented drop tower device designed to impact the palmar surface of the hand with the wrist extended to approximately 90 degrees. Impact severity was modulated by adjusting the boundary condition of the elbow. Elbow reaction force and deformation of the specimen (deflection of the palmar surface of the hand toward the elbow) were measured. Bone-implanted strain gauges were used to detect the time of fracture. Injury risk functions were developed using parametric survival analysis with a cumulative Weibull distribution.
Of 14 specimens, 10 exhibited a fracture to the wrist or forearm after test (one specimen was excluded from the analysis). Injury severities varied from nondisplaced fractures of the radius to severely displaced fractures and/or fracture-dislocations of the carpal bones. Of the potential predictors studied, the specimen deflection expressed as a percentage of the initial specimen length produced the injury risk model of best fit (50% risk of fracture at 1.69% deflection; 95% confidence interval, 1.38-2.07% deflection). The value of the elbow reaction force corresponding to a 50% risk of injury was 4.34 kN (3.80-4.97 kN).
These results provide information for the prediction of wrist and forearm injury in biomechanical models simulating impacts in the field and provide tolerance information for the development of injury mitigation countermeasures.
手腕/前臂复合体是人体最常发生骨折的部位之一，但人们对其耐冲击性了解甚少。本研究旨在量化成年男性前臂 - 手腕复合体在模拟轴向冲击伸展手部的负荷下的损伤耐受性。
测试了15个离体尸体前臂/手腕标本。通过一个仪器化的落塔装置施加负荷，该装置设计用于在手腕伸展至约90度时冲击手掌表面。通过调整肘部的边界条件来调节冲击 severity。测量肘部反作用力和标本的变形（手掌表面向肘部的偏转）。使用植入骨的应变片来检测骨折时间。使用具有累积威布尔分布的参数生存分析开发损伤风险函数。
在14个标本中，10个在测试后出现手腕或前臂骨折（一个标本被排除在分析之外）。损伤 severity 从桡骨无移位骨折到严重移位骨折和/或腕骨骨折脱位不等。在所研究的潜在预测因素中，以初始标本长度的百分比表示的标本偏转产生了最佳拟合的损伤风险模型（在1.69%偏转时骨折风险为50%；95%置信区间，1.38 - 2.07%偏转）。对应50%损伤风险的肘部反作用力值为4.34 kN（3.80 - 4.97 kN）。
这些结果为模拟现场冲击的生物力学模型中手腕和前臂损伤的预测提供了信息，并为损伤减轻对策的开发提供了耐受性信息。
