A Method of Calculation for Contact Pressure between Femoral Head and Cup of Artificial Hip Joint

摘要

A method of calculation for contact pressure between a hard femoral head and soft plastic cup of hip joint was studied. Providing the contact pressure is proportional to the radial deformation of the cup, an equation of equilibrium in terms of non-dimensional parameter was derived. Once the magnitude of parameter is determined by solving the equation, the contact pressure distribution is easily obtained. An effect of the radial clearance between a femoral head and cup on contact pressure was evaluated by using the equation. Furthermore an effect of Young's modulus and thickness of a plastic cup on contact pressure were also evaluated. According to the results, contact pressure increased with an increment of clearance and Young's modulus. The contact pressure increased with a decrement of thickness of plastic cup. Analytical solution was compared with the FEM analysis and the agreement was confirmed. An equation offrictional torque was also derived.