| Objective1, Established a ONFH finite element model (FEM) with good geometric and physical similarity, what can be repeatedly used for dynamic simulation analysis.2. Based on the3D finite element method, dynamic simulate and analysis the biomechanical changes of the femoral head after treatment by JianPiHuoGu decoction, and provided a biomechanical reference for the JianPiHuoGu decoction treatment.Method1. Established a ONFH finite element model for dynamic simulation analysis(1) Selected1ONFH patient with unilateral osteonecrosis in ARCO stage Ⅱ and take the other normal hip as control group.(2) Imported the patient’s CT data into Amira software, then layer and layer respectively segmented and extracted the profile of femoral head cancellous bone, necrosis bone, lastly built their3D FEM.(3) Used the Geomagic software to sampling, smoothing and surface fitting the model, then load the model into Ansys14.0FEA software.(4) In the Ansys software, after the FEM be meshing, Material properties definition and assignment, definition of boundary conditions and loading area etc. And then respectively built the normal and ONFH FEM according to the cancellous bone and cortical bone whether be distincted.(5) To analysis the stress characteristic of each femoral head FEM under the normal walking, then selected the more reality and accuracy method to establish the model.2. A biomechanical study on the NONFH in ARCO stage Ⅱ by JianPiHuoGu decoction treatment(1) Slected the4patients who were treatmented effciency by JianPiHuoGu decoction in one year and then collected their CT dicom data.(2) Respectively established the4patient’s before and after1year’s FEM.(3) Respectively let the ONFH model weight-bearing area under the walking, slow running, rapidly running’s mechanical loading and then observed the equivalent stress and displacement of the femoral head, finally analysis the collapse risking of femoral head under the different gait.Result1. Respectively established the normal and osteonecrosis femoral head finite element model(1) Among the ONFH model,when the cancellous bone and cortical bone were distinguished, the model’s nodes and units respectively are189287,123274and the undistinguished model repctively are562682,406764. However, in the osteonecrosis bone model,the distinguished model’s nodes and units respectively are45385,30006and the undistinguished are6213,3724.But in the normal femoral head model, whether the cancellous bone and cortical bone were distinguished,the nodes and units are all did not show singificant difference.(2) Among the normal femoral head model are all presented a stress concentration on the medial and lateral femoral neck and proximal femoral shaft. In the femoral calcar, which burden the people’s loading, but in this area didn’t show a stress concentration.This characteristic is correctly as human’s physiological characteristics and the previous research. Among the ONFH model are all presented a stress concentration on the medial and lateral femoral neck and small rotor, especially in the distinguished model.Compared with the normal femoral head model, in the ONFH model the stress have taken place, especially in the femoral head multiple place showed stress concentrated, that can be easily caused the osteoncrosis femoral head further development.(3) Among each model, the biggest displacement place is the weight-bearing area, what can be easly caused the femoral head collapse. Among the distinguished model, the displacement in the necrosis femoral head are all higher than the normal femoral head in the same area, but this is not obviously in the undistinguised model. The displacement level in the weight-bearing area is obviously much higher than other area.(4) Among the model, the ONFH model’s maximum stress value (MSV) is higher than the normal model, especially when the cortical bone and cancellous bone be distinguished, the value form52.1103GPa reduced to30.1069MPa. But when the cortical bone and cancellous bone not be distinguished, the maximum displacement value (MDV) in the left and right model respectively is1.3214mm,1.0022mm.This is not match with the real situation. However, in the distinguished model, the MDV in the left model is1.0069mm, this is obviously higher than the right value0.5836mm. From the above analysis, this result indirectly show under the same mechanical load, the necrosis femoral head wight-loading area’s collapse risk and level is much more higher.2. A biomechanical study on the NONFH in ARCO stage II by JianPiHuoGu Formula treatment.(1) Under gait of the normal walking, slow running and rapidly running,compared with the pre-treatment, all of the four patient’s post-treatment maximum stress and displacement value obviously decreased, the displacement value post-treatment is obviously smaller but the stress is significant higher on femoral head weight-bearing area (p<0.05), however, the osteoncrosis stress is obviously decreased than pre-treatment (p<0.05)(2)According to the collapse criterion, fistly, under the gait of normal walking, the stress value on necrosis bone mostly is less than0.55MPa, the possibility of the necrotic bone collapse is low. Sceondly, under the gait of slow running, the stress value on osteonecrosis is cline to0.55MPa, in this gait, the risk of femoral head collapse increased, we should make active treatment to prevent the collapse of the femoral head. Finally, Under the gait of rapidly running, the stress value on osteoncrosis is higher than0.55MPa.In this gait, the risk of femoral head collapse is obviously, we should inform the patient to make active treatment and avoid rapidly running,or the risk would be seriously.(3)Under the three kinds of gait, the displacement value of the femoral head is gradually creased. In the ONFH model,the maximum stress and the displacement value decreased obviously than pre-treatment. Post-treatment the displacement value on the osteoncrosis model was decreased, but the stress on the femoral head weighting-area was decreased.By the frequency of gait increasing, the stress and displacement values increased significantly on the ostenecrosis weighting-area and the risk of femoral head collapse gradually increased.Conclusion1. Established the femoral head finite element model(1) With the FEA software, we successfully established a FEM what has better geometric and physical similarity and it can be repeated application and provided for dynamic mechanical simulation analysis.(2) Compared to the normal femoral head model, the cancellous bone and cortical bone material to be distinguish seems to be more necessary in ONFH model established.2. Abiomechanical study on the NONFH in ARCO stage II by JianPiHuoGu decotion treatment.(1) The JianPiHuoGu decotion can effectively enhanced the supporting capability of ONFH’s weight-bearing area and reduced the compressive stress of osteonecrosis and the collapse risk, fundamentally improve the interior mechanical environment of ONFH,finally reduced the collapse risk of femoral head.(2) By the gait frequency gradually increasing, the risk of femoral head collapse were gradually increasing, especially under the rapidly running.Therefore under the rapid running, the patient should be avoided running during the treatment stage. |
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