髋关节三维有限元模型的构建及关节囊修复预后分析

目的 构建髋关节置换的三维有限元模型，模拟关节囊修复和术后康复活动，比较两种关节囊修复方法的生物力学差异。方法 以骨-囊-骨方式采集6个冷冻髋关节的后关节囊韧带复合体标本，用万能材料试验机测定标本的载荷-应变曲线等力学特性。采集一名志愿者骨盆及下肢薄层CT扫描数据导入Mimics软件，构建髋关节的三维模型，在CATIA软件中建立臼杯、股骨假体、关节囊的三维数字模型导入Mimics，模拟行全髋关节置换手术（THA），装配后数据导入ABAQUS软件中，根据解剖研究、力学结果、本构方程设定关节囊属性，测量、比较屈髋过程中，解剖和传统修复关节囊的生物力学差别。结果 关节囊韧带复合体标本测试平均极限拉伸应变（39.21±5.23）%、极限拉伸强度（1.65±0.38）MPa。有限元模型应力-应变曲线与标本力学测试的结果相似，符合关节囊的力学特征，屈髋活动时解剖修复的关节囊应力分布均匀，均在极限拉伸强度范围内，传统修复关节囊应力分布不均，屈髋90°时下部关节囊的拉伸应力达到关节囊标本的拉伸强度极限。结论 有限元模型可用于动态、量化、可视化分析髋关节囊应力分布，解剖修复比传统修复更符合生物力学特点。

Prognostic evaluation of hip joint function following capsule repair based on a threedimensional finite element analysis model

Objective To construct a three-dimensional (3D) finite element mechanical model of total hip arthroplasty for comparison of biomechanical differences of the hip joint following capsule repair and postoperative rehabilitation. Methods Six frozen specimens of hip joint posterior capsule ligament complex were collected in a bone-capsule-bone manner, and the load-strain curve and other mechanical properties of the specimens were tested using a universal material testing machine. Thin-section CT data of the pelvis and lower limbs obtained from a volunteer were imported into Mimics software to construct a 3D model of the hip joint. Digital models of the cup, femoral prosthesis and joint capsule were created in CATIA software and imported into Mimics to simulate total hip arthroplasty; the assembled data were imported into ABAQUS software. The properties of the capsule were set according to results of the mechanical test, anatomical studies, and constitutive equations, and the biomechanics of the anatomically repaired and conventionally repaired capsules were compared during hip flexion. Results The results of testing on the 6 capsule specimens showed a mean ultimate tensile strain of (39.21±5.23)% and a mean of ultimate tensile strength of 1.65±0.38 MPa. The stress-strain curve of the finite element model was consistent with the results of mechanical test on the specimens and the biochemical characteristics of the capsule. The stress was distributed evenly in the anatomically repaired capsule during hip flexion but not in the capsule repaired through the conventional approach; the tensile stress in the lower part of the conventionally repaired capsule reached the ultimate tensile stress measured on the capsule specimens at a 90° flexion. Conclusion The finite element model allows dynamic, quantitative and visual assessment of stress distribution in the hip joint capsule, and compared with the conventional approach, anatomical repair can achieve better biomechanical properties of the capsule.