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

Abstract

A method of calculation for contact pressure between a hard femoral head and soft plastic cup of a hip joint was studied. Providing that the contact pressure is proportional to the radial deformation of the cup, an equation of equilibrium in terms of a nondimensional parameter was derived. Once the magnitude of the 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 using the equation. Furthermore, the 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 the plastic cup. The analytical solution was compared with the finite element method (FEM) analysis and the agreement was confirmed. An equation of frictional torque was also derived

KEYWORDS:

• Biolubrication
• Joints
• Spherical (pivot)
• Contact Mechanics
• Polymeric Bearings