| Asceptic loosening of the component following THA is a common late complication. It is very difficult to treat actabular component loosening with bone defect,especially in dome of acetabulum. Foreign specialist attempted to construct the bone defects with Bilobed,Oblong presthesis or Muller ring.The result of follow-up in short-term time is good,but the result with long-term follow-up shows very worse. In early 1990's, General Hospital of PLA independently designed acetabular component with three-fins with intellectual property right. The three-fins actabular component has been used in revision surgery for 10 years and excellent result has been obtained.In order to reinforce the relative fundimental resraech of the three-fins acetabular component,we regard the Finite Element Analysis (FEA)as a effective method to design and optimize implant.According to the type I of AAOS, we simulated segmental bone defect of the superior acetabulumBasic related research of the three-fin actabular component was done in this study. Combined rosette strain gages with digital speckle correlation method(DSCM) about pilvis bone with simulating bone defect of the type I of AAOS in vitro,we investigated the Mises stresses and displacements surrounding the acetabular bone when the three-fins actabular component had implanted in actabulum.At the same time,we validated three-dimensional FE model.1. Three-dimensional FEA of three-fins acetabular components with superior segmental bone defect of actabulum in vitro.Objective: To intruduce a new FE model of pelvis bone and three-fin acetabular component and analysis its stress distribution and conculate its displacements.Materials and method: Using CT scan data of a healthy volunteer ,we tranfer two-dimensional data to three-demensional model with the help of Unigraphics17.0 software.We constructed FE three-demensional models with superior segmental bone defect of actabulum and 4 kinds of three-fins actabularcomponent based on spreaded degrees of lateral fins(0° ,36° ,45° ,60° )and 2 kinds of control groups(Bilobed,blank). We simulated the actual position to place implant into acetabular bone.All of them are 7 groups.Then we created mesh-20377 elements and 4835 nodes and confined the boundary situation and loaded. By FEM we obtained von Mises stresses and displacements graphs about pelvis and three-fins acetabular component under static load of single leg.Results:(1) We selected 5 nodes in all groups to compare with each other.Two factors that were study nodes and spreaded degrees of lateral fins of three-fins components might influence statistic result. The statistic result reveal no statistic difference between 36° and 45° group.But the rest of groups show statistic difference (P<0.05) .(2) The maximal Von Mises stress of three-fins actabular component was 15.2 MPa which occurred in 0° study group. The minimal Von Mises stress of three-fins actabular component was 0.74 MPa.The statistic correlation analysis were performed to the peak values of Von Mises stress and spreaded degrees of lateral fins of three-fins components. No statistic difference were obtained.(3) We also conculated the micromotions between three-fins actabular component and acetabulum bone in standing situation with single leg.2. Displacements research of three-fins acetabular component surrounding acetabulum bone with segmental bone defect using Digital Speckle Correlation Method(DSCM)Objective: To set up the experimemtal model with superior segmental bone defect in acetabulum and implant the three-fins actabular component.To examined the displacements of three-fins actabular component in actabulum with simulating single leg position in vitro,then assess the micromotion between them using Digital Speckle Correlation Method(DSCM).Materials and method:Four kinds of three-fins component were made based on measurement of diameter, depth and roof thickness of acetabular specimens.These kinds of three-fins actabular component based on spreaded degrees of lateral fins(0° ,36° ,45° ,60° ). We created the superior segmental bone defect of actabulum in four cadaver pelves specimens,then simulated the actual position to place implant into acetabular bone.After being made up the speckle,then specimen to test the pelvic displacement datas simulating the static load with single leg on the mechanic machine.Progressive load was graded into 300N, 600N and 900N.We obtained the displacement graphs of pre-loaded and post-loaded informations about pelvis bone.Resuls:(1) Based on computed datas of displacements,we were informed that the maximal displacement of selected local position of acetabulum was 192 μm which occurred in 0° study group. The minimal displacement of selected local position of acetabulum was 112 μm.(2) Comparison with the same position of FEM,rariance statistic ananlysis was taken about 3 factors that were displacements,spreaded degrees of lateral fins and testing methods.The result show no statistic difference were obtained between DSCM and FEM (P>0.05) . The result valitafied the reliability of FE model.3. Von Mises stresses research about three-fins actabular components and pelvis bone with segmental bone defect of acetabulum using Rosette Strain Gages Method(RSGD)Objective: To set up the experimemtal model with superior segmental bone defect in acetabulum and implant the three-fins actabular component.To examined the Von Mises stresses of pelvis bone with simulating single leg position in vitro using Rosette Strain Gages Method(RSGD).Materials and method.Four kinds of three-fins component were made based on measurement of diameter, depth and roof thickness of acetabular specimens. These kinds of three-fins actabular component based on spreaded degrees of lateral fins(0° ,36° ,45° ,60° ). We created the superior segmental bone defect...
|
PDF Full Text Request