【作者】 郑立；

【导师】 罗教明；

【作者基本信息】 四川大学 ， 生物医学工程， 2004， 硕士

【摘要】 本文在查阅分析大量的文献基础上，针对大腿假肢植入性经皮器件动态生物密封和长期使用下骨质疏松的难题，提出了一种新型植入性经皮器件：采用多段式骨植入体结构，在保证其稳定性的同时，减少与骨整合的区域，降低应力屏蔽，另外采用网孔弧形罩屏蔽肌肉运动应力对经皮密封部位的影响，有利于动态生物密封的实现。基于人体股骨CT和生理数据，在步态情况下对不同截肢部位植入性经皮器件骨植入体及周围骨应力进行有限元分析，对设计进行了评价和优化，并以狗为动物实验模型，进行实验验证，通过本文研究得出以下结论： 1．模型和加载条件的近似程度对有限元分析结果有较大的影响 通过对轴对称模型和基于CT数据重建模型，以及轴向简化加载和步态最大生理加载条件的分析，得出轴对称模型和轴向加载计算结果与实际情况有较大的偏差；从CT数据出发，建立了较准确的有限元分析模型，且采用后倾14度，最大生理载荷加载，符合人体步行最大加载生理姿态，约束和近似条件与实际情况接近，对不同截肢部位下植入性大腿假肢一段式骨内植入段的应力分布进行了分析研究，所得结果与真实情况接近。 2．多段式骨植入体的设计及结构优化显著降低应力屏蔽 有限元结果表明新型的多段式骨内植入体周围应力屏蔽相比于传统一段式植入体得到了有效减轻，与健康自然骨应力分布更为接近，尤其是在股骨远端。多段式结构股骨远端部位和植入体末端部位的骨整合段长度在接近1cm左右下周围骨应力与正常骨水平最接近，总长在9cm以上有利于缓解植入体末端骨整合段周围的应力集中。由于多段式植入体总长的保持以及结构强度的较小改变，使得植入体的稳定性得到了很好的保证。为了快速、方便的获得结果，采用的股骨模型、加载条件等简化条件，尽管所得结果与实际有一定偏差，但在等同条件下对新型植入体与传统植入体进行比较，其分析结果是有效的。 3．较真实条件模拟下，有限元结果表明不同截肢部位多段式骨植入体周围应力屏蔽明显改善 基于CT数据建立股骨模型，选择人体步行最大生理载荷条件下，采用有限元分析方法，在不同截肢部位下对优化的多段式植入体进行进一步的分析研究，结果表明，不同截肢部位新型多段式骨内植入体周围骨应力分布状况有一定差异，但应力屏蔽的程度相比于同一截肢部位下一段式植入体得到了有效减轻，与健康自然骨应力分布更接近，尤其在植入体附近部位。 4．网孔弧形罩经皮器件的设计及通过初步的生物学评价进行结构优化以满足生物密封要求 经皮部件设计采用新型的网孔弧型罩结构，能与组织形成牢固结合，起到固定软组织的作用，具有钛板的强度，可屏蔽肌肉收缩产生的应力对经皮密封部位的不利影响。弧形的设计，使植入体与组织充分接触促进结合。经皮部分设计采用凹槽结构，可以防止经皮移行。为验证网孔弧形罩结构的生物学性能，进辛了了相关动物实验和生物学评价，结果表明，皮下植入部分采用HA喷涂处理的钦合金为材料，3mm的孔径、lmm的厚度以及两步植入手术过程中90天的愈合期对植入体一组织结合的较为有利。 5，采用多段式骨植入体和网孔弧形罩结构的植入式假肢的动物实验初步结果表明设计的合理性以后腿截肢的狗作为动物实验模型，根据本文研究结果，设计并进行了植入性经皮器件的动物实验，采用两步植入手术方法，愈合期间的x光片结果表明，植入一个月后，植入式假肢能保持良好的稳定性，初步证明了骨内植入体和经皮部件设计的合理性。实验动物同时截肢和假肢修复，能获得更好的效果;而截肢一段时间后修复，股骨残端有骨质疏松现象发生，是不利于植入式假肢使用的因素。关键词:植入性经皮器件生物密封骨质疏松多段式骨植入体 软组织固定有限元分析动物实验更多还原

【Abstract】 To reduce osteoporosis caused by osseointegrated implant and failure to attain the dynamic biological seal for osseointergrated percutaneous device for artificial leg, a new type of device was developed in this article: the multi-part osseointegrated implant that can reduce stress shielding by diminishing the area in contact with bone and the newly designed percutaneous device with perforated arc flange to shield the percutaneous site from the contraction of muscle, beneficial to realize the dynamic biological seal. Based on CT data of human femur and physiological information, stress analysis by way of FEA of osseointegrated implant and surrounding bone during a normal walking to estimate and optimize the structure of osseointegrated implant, and the evaluation of the theoretical design by adopting dog as object of animal experiment were applied. The conclusion is as below:1. The impact of accuracy of model construction and representativeness of load on FE result With the construction of accurate FE model of femur based on CT data, the application of maximal load angled 14 degree with axial direction during normal walking circle, as well as the confinement and other simulating conditions approximate the reality, 3D finite element analysis was carried out to investigate the stress distribution around one-part osseointegrated implant of osseointegrated artificial leg at different amputated position. The result is much closer to the practical situation than under the axisymmetric model and axial load.2. Optimized multi-part implant can reduce stress shielding greatly FEA result showed that stress shielding reduced greatly around the new multi-part osseointegrted implant compared with traditional one -part implant, and is more close to the level of intact bone, especially at distal region of femur. For multi-part implant, the amount of stress shielding reduced most when the length of osseointegrated part at distal end and implant end are nearly 1cm. Full length of 9cm is favorable for multi-part implant to mitigate stress concentration caused by osseointegrated part at implant end. As the full length and stiffness of the new type of implant remain, the stability of implant can be maintained. Simplified model offemur and condition would make the result deviant to some extent, but it is efficient and convenient to get result that is valid to compare the new type of implant with the tradityional one under the same conditions.3. FE results revealed stress shielding reduced markedly around multipart implant at different amputated position under simulated condition much close to reality Using CT data based model of femur and applying maximal load during normal walking, FEA was used to further evaluate the optimized multi-part implant. Results revealed that stress distribution varied with the amputated position. Meanwhile, compared with one-part implant at the same amputated position, stress distribution around multi-part implant was more close to that of intact bone, which indicated that stress shielding was reduced effectively, especially at peri-implant region.4. Percutaneous device with perforated arc flange optimized by biological way can achieve biological seal Pecutaneous device was designed with perforated arc flange and groove-shaped percutaneous part, intended to integrate with the soft tissue firmly. Preserved with the stiffness of plate, it is helpful to shield the adverse effect of stress on the exit caused by muscle contraction. Also, the design of arc shape of flange is to well match the appearance of end of residue limb and assure the sufficient touch of implant and tissue to facilitate the integration. Besides, the groove-shaped percutaneous part was aimed to prevent epithelial downgrowth. To test the biological function of perforated arc flange, correlative animal experiment and biological evaluation were done. Result showed that to choose HA-sprayed titanium alloy, pore diameter of 3mm and implant thickness of 1mm for perforated arc flange, as well as 90 days of healing period during two-stage s更多还原