| 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...
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