The Three Dimension Finite Element Analysis And Clinical Meaning Of The Influence On Total Hip Replacement Of Development Dysplasia Of The Hip From The Different Position Of The Osteotomy Of Acetabular Medial Wall

The total hip replacement(THR) in the advanced stage of the development dysplasia of hip is the best choice to relieve pain and to improve the function of hip joint. Different from typical total THR, the THR of the development dysplasia of hip possess many difficulties,the most difficult one is acetabular reconstruction. The difficult point is how to solve the conflict among acetabular reconstruction in genuine acetabulum, the normal angles of acetabular cup input and enough bone coverage of acetabular cup. Recently, there is an acetabular reconstruction technique--the osteotomy of acetabular medial wall,this new technique is to cut the genuine acetabulum medial wall and push the bone block inwards in order to deepen genuine acetabulum. This method not only guarantee the normal angles of acetabular cup input and enough bone coverage of acetabular cup,but also avoid structure bone graft at the lateral of acetabulum. Comprehending the present reports of osteotomy of acetabular medial wall THR, we can conclude that the opinions of best position of osteotomy is different.[Objective] Using the three dimension finite element analysis,we study wether the different positions of osteotomy of acetabular medial wall THR in treating the development dysplasia of hip may effect the stress distribution in acetabular cup-bone interface, if they effect,to study how to effect stress distribution.By this experiment,we also practice individual surgery design of hip joint, and find the best position of osteotomy of acetabular medial wall in the aspect of biomechanics.[Methods]Firstly,use the finite element analysis software-- SOLIDWORKS to reconstruct the three-dimensional model of the pelvis of the development dysplasia of hip from CT scan picture. In circumstance of the computer, use the CAD function of SOLIDWORKS to simulate the osteotomy of acetabular medial wall in pelvis model.Then meshing the pelvis and acetabular cup model.Finally, use the mechanics analisys tool bag-COSMOS in SOLIDWORKS to analize three-dimensional model, the fetch the stress data in acetabular cup-bone interface. After statistics analysis of the experiment result,find how the different position of osteotomy effect the stress distribution in acetabular cup-bone interface.[Results] The compressive stress in acetabular cup-bone interface: when the position of osteotomy is at one forth of acetabular diameter,the compressive stress distribution in different acetabular quadrant is averagest. When the position of osteotomy is at three eighths of acetabular diameter, the compressive stress distribution in different acetabular quadrant is unaveragest.The condition of compressive stress in acetabular cup-bone interface is same among the different position of osteotomy,the condition is that the compressive stress of upper-bihend quadrand is biggest,the compressive stress of antre-low quadrand is smallest, the compressive stress of antre-upper and post-low quadrand is intermediate.For single quadrand ,the compressive stress among different position of osteotomy is all same. The shear stress in acetabular cup-bone interface: when the position of osteotomy is at three eighths of acetabular diameter,the shear stress distribution in acetabular cup-bone interface is biggest,the shear stress of other position of osteotomy is same.The shear stress in different quadrand of different position of osteotomy is same. The affect of shear stress in different position of osteotomy to single quadrand is very little,and the rule of the affect is not obvious.[Conclusion]1. The affect of the different position of osteotomy to the compressive stress in acetabular cup-bone interface is not obvious.2. The affect of the different position of osteotomy to the shear stress in acetabular cup-bone interface is very little, and the rule of the affect is not obvious.3. The best position of osteotomy for this pelvis model is at one forth of acetabular diameter,the worst position is at three eighths of acetabular diameter.