TENSILE BONDING STRENGTH OF THE CEMENT-PROSTHESIS INTERFACE

A widely held belief among orthopedic surgeons is that there is no adh esion between polymethylmethacrylate bone cement and metal. However, a bond does form between the cement and the standard grit-blasted impla nt finish. Moreover, it has been shown that disruption of this bond or ''debonding'' of this interface is a major factor in the initiation o f failure of some cemented total joint arthroplasties. It is the purpo se of this study to determine the tensile pull-off strength of the bon e cement-implant surface interface. A 1.27 cm (0.5 in) layer of Simple x-P bone cement was cured between two Co-Cr-Mo pins of 2.22 cm (0.875 in) diameter which had the standard implant finish on the surface that was interfaced with the cement. The specimens were tested in an MTS m achine in stroke control with a cross head rate of 1 in per minute. Th e maximum load to failure was recorded. Bonding of the cement to the s urface does occur. The tensile pull-off strength of the bone cement-im plant surface interface is approximately 5 MPa. Other studies have sho wn that maintaining this bond between the stem and cement is important in maintaining the stability of cemented total joint arthroplasties.