临床应用性：目前比较公认的说法是：尺侧皮质受损大于桡侧。本文则形象地证明了这一观点，在单纯骨因素下，尺侧应力大于桡侧应力。为进一步阐明肘内翻机制提供了有益的思路。

偏倚或不足：由于儿童肱骨下端软骨层较厚，且不同年龄骺软骨形状略有差异，而CT图像不能精确反映这些。所建模型外形不像成人的模型那样具有稳定性。

重要的概念：有限元法是一种在工程科学技术中广泛应用的数学物理方法,早期主要是建立简单的力学模型以及简单的生物力学的分析等理论方面的研究。随着计算机技术的发展和大型有限元软件的开发，有限元技术逐步应用到了临床，用来指导一些实际的问题。目前，有限元法在人体骨骼的各个部位几乎都有模型，并且人们将周围的韧带、肌肉等组织赋于模型，分析其力学特性，模拟体外实验无法完成的工作。

摘要
背景：有限元法最核心的部分就是有限元模型的建立，所建立模型的精确度和建模所需的时间直接体现了该方法的可行性与有效性。随着建模方法的发展，骨科有限元分析的范围也逐渐从早期的股骨拓展到脊柱、四肢，而采用DICOM数据直接建模法建立儿童肱骨模型并进行有限元分析，国内外文献尚未见相关报道。
目的：建立并验证儿童肱骨三维有限元模型，并应用该模型探讨儿童肱骨髁上骨折和肘内翻发生的机制。
设计、时间及地点：观察验证性实验，于2007-07/09在大连交通大学机械工程学院CAD/CAE研究中心完成。
对象：选择山西医科大学第二医院放射科1例左肱骨髁间粉碎骨折患者CT图像，男性，4岁，采集右侧对照CT图像。
方法：扫描层厚为1.25 mm，无间隔，将所得图像数据导入到医学图像处理软件mimics中，生成肱骨三维模型。然后以IGS格式输出导入到专业有限元网格制作软件HYPERMESH中，生成三维有限元模型。最后导入有限元分析软件ANSYS进行有限元分析。
主要观察指标：不同载荷下尺侧和桡侧平均应力值。
结果：①模型检验与体外生物力学实验的数据基本一致。②肱骨髁上区可见明显的应力交界区。③肱骨尺侧应力大于桡侧。
结论：①本实验所建立模型真实可信，可用于生物力学分析。② 肱骨髁上骨折模型与实际骨折基本一致，进一步形象地证实了肱骨髁上骨折发生于骨形状及皮松质骨交界区。③尺侧皮质受损大于桡侧是肘内翻畸形的基本力学因素。
关键词：儿童； 三维有限元模型；肱骨髁上骨折；肘内翻；应力；组织构建

杜玉勇，尹芸生，薛晓峰，段圆慧.构建并验证儿童肱骨髁上骨折三维有限元模型[J].中国组织工程研究与临床康复，2008，12(22):4265-4269 [www.zglckf.com/zglckf/ejournal/upfiles/08-22/22k-4265(ps).pdf]

Construction and validation of the finite element model of humeral supracondylar fracture in children

Abstract
BACKGROUND: Establishment of finite element model is the key in finite element analysis. The accuracy and modeling time cost directly reflect the feasibility and validity of modeling method. With the development of model establishment, the scope of finite element analysis for orthopedics department is expanded from early femur to spine and extremities. To date, there are no reports about DICOM data method for child humeral modeling and finite element analysis at home and abroad.
OBJECTIVE: To set up and verify the finite element model of child humerus and to analyze the injury mechanisms of supracondylar humeral fracture and cubitus varus.
DESIGN, TIME AND SETTING: The observation was performed at CAD/CAS Research Center, College of Mechanical Engineering, Dalian Jiaotong University from July to September 2007.
PARTICIPANT: CT images of a 4-year-old male child with comminuted fracture of left humeral condyle were collected from Department of Radiology, Second Hospital of Shanxi Medical University. The CT images of the right side served as control.
METHODS: The humeral condyle was scanned by CT with l.25 mm interval. The CT images were (DICOM) were dealt with MIMICS to form 3-dimentional (3D) humeral model. Then the model was output by IGS form and put in HYPERMESH software to build up 3D finite element model. Finally, the model was put in the ANSYS software for finite element analysis.
MAIN OUTCOME MEASURES: Average ulnar and radial stress under different loads.
RESULTS: The model kept coincidence with the data of biomechanical experiment in vitro. A clear junctional zone was found on the supracondylar humerus. The ulnar stress was larger than the radial stress.
CONCLUSION: The model is reliable and can be used for biomechanical analysis. The fracture model of supracondylar humerus is almost identical to practical fracture, indicating the fracture of supracondylar humerus occurs in the juncture of cortical bone and cancellous bone. Damage of ulnar cortex larger than the radialis is the basic mechanical factor for cubitus varus.

Du YY, Yin YS, Xue XF, Duan YH.Construction and validation of the finite element model of humeral supracondylar fracture in children. Zhongguo Zuzhi Gongcheng Yanjiu yu Linchuang Kangfu 2008;12(22):4265-4269(China)
[www.zglckf.com/zglckf/ejournal/upfiles/08-22/22k-4265(ps).pdf]