Date of Graduation

2001

Document Type

Thesis

Degree Type

MS

Committee Chair

Timothy L. Norman

Abstract

Theclinical success of the polished tapered stem in particular has widely been demon strated. However, the mechanical environment of this stem is not understood. The overall goal of this research was to understand the influence of bone cement creep on the me chanical environment of a polished tapered stem using a physiological three-dimensional finite element model. Specifically, the objectives were to: (1) Investigate the influence of three different commercially available cements on stem subsidence and cement mantle stresses. Both short (24 hours) and long (16 years) term simulations were conducted; (2) Consider the effect of cyclic loading (using a creep law developed for such loading) on stem subsidence and cement mantle stresses; and (3) Determine the invitro stem cement interface friction coefficient through parametric analysis. Results indicated that the stem subsidence and cement mantle stresseswere influenced by the choice of acrylic bone cement due to differences in the creep response. After a 24 hour period, the maximum stem subsidence was the greatest for Simplex cement. The maximum von Mises stress in the cement was also observed for Simplex cement under cyclic loading conditions. The long term study showed that the subsidence continues in creasing slowly (3 × 10−7 mm/hour) even after 16 years. However, von Mises stresses dropped to a nearly constant value. The value of the stem cement interface friction coef ficient was obtained to be 0.031.

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