Finite element analysis of acetabular medial wall displacement osteotomy in adult acetabular dysplasia / 中国组织工程研究

ABSTRACT

BACKGROUND: Adult acetabular dysplasia in advanced stage combined with hip joint osteoarthritis should undergo total hip replacement. The severity of acetabular lesion is various in different patients, which leads to significantly increased difficulty in reestablishing acetabulum. Acetabular medial wall displacement osteotomy can solve the component of acetabular prosthesis, but the displacement range of the acetabular medial wall following osteotomy is controversial.OBJECTIVE: To look for a suitable displacement range of acetabular medial wall following osteotomy by computer-aided design finite element analysis.METHODS: SolidWorks 2008 software was used to establish three-dimensional models of acetabular dysplasia pelvis. Acetabular medial wall displacement osteotomy was simulated to make acetabular medial wall bone displace from 2 mm bone contact to 7 mm bone contact in the pelvic cavity. One experimental group was set at 1 mm intervals, totally 10 experimental groups. The acetabulum in each group was split into four quadrants. The prosthesis acetabulum-bone interface in each group was analyzed by computer simulation contrast mechanics experiment. The Mises stress and shear stress values were measured between acetabular prosthesis and bone interface.RESULTS AND CONCLUSION: In groups 1, 5, 6, 9 and 10, the Mises stress was unevenly distributed in posterior inferior, anterior superior and anterior inferior quadrants. In groups 2, 3, 4, 7 and 8, the Mises stress was evenly distributed in posterior inferior,anterior superior and anterior inferior quadrants. Of them, the stress was most even in the group 4. In groups 2, 3, 4, 7 and 8, the shear stress was evenly distributed in the above-mentioned three quadrants. The shear stress was lowest in the groups 7 and 8.These indicate that joint force in the acetabulum mainly focused in the posterior superior quadrant. With the displacement of acetabular cup, the contact area of acetabular cup and bone would gradually increase, which finally increased the Mises stress in the contact surface. However, shear stress decreased with displacement of acetabular medial wall. Therefore, the suitable displacement range of acetabular medial wall osteotomy is 1 mm away from the pelvic cavity and 1 mm complete embolism in the pelvic cavity. The optimal position was 1 mm complete embolism in the pelvic cavity.