Development of PMMA-precoating metal prostheses via injection molding: residual stresses

The effects of curing history on residual stresses in bone cement during hip arthroplasty

During cement curing in total hip arthroplasty, residual stresses are introduced in the cement mantle as a result of curing shrinkage, thermal shrinkage, and geometrical constraints. These high residual stresses are capable of initiating cracks in the mantle of cemented hip replacements. The purpose of this study was to determine the residual stresses in the cemented hip replacements. The finite element method was developed to predict the residual stresses built up in joint arthroplasties. Experimental tests were then performed to validate the numerical methodology. Then the effects of curing history on the residual stress distribution were investigated with finite element simulations. Results showed that the predictions of the thermal shrinkage residual stresses by the developed method agreed with the experimental tests very well. The residual stress buildup was shown to depend on the curing history. By preheating the prosthesis stem prior to implantation, a desired low-level residual stress at the critical prosthesis-cement interface was obtained. As a result, this article provides a numerical tool for the quantitative simulation of residual stress and for examining and refining new designs computationally.