D.Y. Jung, S. Tsutsumi (Japan), R. Sekel, R. Frost (Australia), K. Ikeuchi (Japan), and P.
Finite element method, new design, acetabular cup, von Mises stress, contact stress
In total hip replacement, polyethylene acetabular cup liner back wear particle generation has remained as a significant cause for prothesis loosening in the medium and long term. In this study, the new acetabular cup composed of metal-backed shell, metal sandwich, and UHMWPE liner has been developed within an equator plus outer shell to eliminate back-wear debris. The elastoplastic finite element model was used to verify the biomechanical initial strength of the new acetabular cup design. Three-dimensional models were developed of both the newly designed and also a standard acetabular cup, composed of the same metal-backed shell with a standard UHMWPE liner of 6 mm thickness. The von Mises and contact stresses were estimated by changing various loading conditions and radial clearances. The FEM results showed that with loads of five times body weight (5 x 72 kg) and below that the von Mises stresses were lower than the yielding strength (13.3 MPa) in relation to the changes of loading direction. In addition, the peak of von Mises stresses of the new design acetabular on the inner surface of UHMWPE liner were relatively lower than that of the standard cup under all loading conditions. Therefore, the newly designed acetabular cup outer shell with a single piece inner metal polyethylene sandwich liner has been demonstrated on FEA to have sufficient mechanical initial strength to safely withstand loads applied at ranges of angle and radial clearance.
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