全髋关节置换假体不同角度的生物力学特点(2)

Von Mises 应力：是基于剪切应变能的一种等效应力,其含义是当单元体的形状改变比能达到一定程度,材料开始屈服。Von Mises于1913年提出了一个屈服准则,这个屈服准则被称为Von Mises屈服准则。它的内容是：当点应力状态的等效应力达到某一与应力状态无关的定值时,材料就屈服;或者说材料处于塑性状态时,等效应力始终是一不变的定值。在弹塑性有限元计算中,屈服准则的数学描述是整个计算的核心。

王春成，等. 全髋关节置换假体不同角度的生物力学特点 ISSN 2095-4344 CN 21-1581/R CODEN: ZLKHAH

1653

www.CRTER .org

Abstract

BACKGROUND: Total hip arthroplasty is a commonly used treatment, but it is difficult to accurately determine the position of the pelvis, which is easy to cause pelvic displacement postoperatively. Additionally, the implant is likely to present with angle deviation, and the precise location and direction of prosthesis is difficult to identify.

OBJECTIVE: To study the position and biomechanical characteristics of prosthesis in total hip arthroplasty.

METHODS: (1) One male volunteer received CT examination, and a finite element model of the pelvic was established. Three acetabular placement positions (abduction angles of 0°, 20° and 25° combined with anteversion angles of 35°, 15° and 10°) were used to perform total hip arthroplasty, and the peak von Mises stress was detected under a load of 240 N. (2) Six cadaver specimens were collected and received the same interventions with the former experiment, and the stress changes at the bone cortex surrounding femoral shaft and acetabular anterior and posterior wall were measured using resistance strain technology.

RESULTS AND CONCLUSION: (1) The peak von Mises stress in the acetabulum at abduction angle of 25° combined with anteversion angle of 10° increased by 25.7%. The peak von Mises stress in the acetabular cup at abduction angles of 0°, 20° and 25° combined with anteversion angles of 35°,15° and 10° was 135.21, 68.3 and 134.2 MPa, respectively. The peak von Mises stress in the lining at abduction angles of 0°, 20° and 25° combined with anteversion angles of 35°,15° and 10° was 6.8, 3.9 and 6.7 MPa, respectively. The peak von Mises stress in the femoral shaft at abduction angles of 0°, 20° and 25° combined with anteversion angles of 35°,15° and 10° was 127.1, 100.2 and 128.2 MPa, respectively. (2) The stress at the bone cortex surrounding femoral shaft and acetabular anterior and posterior wall at abduction angles of 0° and 25° combined with anteversion angles of 35° and 10° was significantly higher than that at abduction angle of 20° combined with anteversion angle of 15°. To conclude, an abduction angle of 20° combined with anteversion angle of 15° is conductive for functional recovery of the joint.

Subject headings: Arthroplasty, Replacement, Hip; Hip Prosthesis; Biomechanics; Finite Element Analysis; Tissue Engineering

Funding: the Project of the 12th Five-Year Plan of Henan Provincial Educational Science in 2013, No. [2013]-JKGHB-0098

Cite this article: Wang CC, Li MZ. Position and biomechanical characteristics of prosthesis in total hip arthroplasty. Zhongguo Zuzhi Gongcheng Yanjiu. 2017;21(11):1652-1657.

0 引言 Introduction

全髋关节置换是临床常用的手术治疗方法，是一种带有重建性质的手术，对髋关节疾病能取得更好的治疗效果[2-3]。全髋关节置换的应用能精确重建股骨近端解剖结构，其应力分布更加符合生理要求，并且该方法能最大限度的保留机体原有骨质和生理结构，使得术后关节活动能力更加接近正常水平，能增加关节后稳定性[4-5]。

但是，全髋关节置换治疗在临床应用时上存在许多不足[6-7]：①医生在手术台上难以准确判断骨盆的具体方法，容易引起骨盆位置发生明显的位移；②全髋关节置换过程中医师目测存在主观性，其偏差相对较大，容易引起假体位置不准确[8]；③在置换中虽然有辅助器械，但是安全假象发生率较高；④置换过程中由于手术切口暴露限制，导致假体定位缺乏统一的标准，导致假体位置难以准确确定[9]。

随着医疗技术的不断发展，联合前倾技术在全髋关节置换中得到应用，该方法不仅保留传统关节置换中假体的前倾角和外展角，还能有效提高手术成功率，保证机体具有稳定的生物力学。但是，联合前倾技术在使用时前倾角变化范围一般为25°-50°，并且联合前倾技术中35°技术效果最理想，但是该结论尚未得到进一步证实[11-12]。

作者于2014年5月至2016年5月在南阳医学高等专科学校附属医院成功完成志愿者三维有限元分析，探讨全髋关节置换假体角度及生物力学特性。

1 对象和方法 Subjects and methods

1.1 设计 生物力学试验分析。

1.2 时间及地点 试验于2014年5月至2016年5月在南阳医学高等专科学校附属医院骨科完成。 1.3 对象

志愿者：选取男性志愿者1名，年龄66岁，身体健康，骨盆部位未发生骨折，试验均经过南阳医学高等专科学校伦理委员会批准同意，参与者自愿签署知情同意书。

尸体标本：取南阳医学高等专科学校附属医院6具尸体标本，患者中4例意外事故死亡，2例肿瘤死亡，男4例，女2例，年龄53-62岁，平均(55.1±1.9)岁，6具标本大体形态见图1。

1.4 材料 电阻应变计购自浙江黄岩测试仪器厂；双源CT 机购自西门子公司；CCS0-44100电子 …… 此处隐藏：2131字，全部文档内容请下载后查看。喜欢就下载吧 ……