Comparative finite element analysis of the debonding process in different concepts of cemented hip implants.

Damage accumulation in the cement mantle and debonding of the bone-cement interface are basic events that contribute to the long-term failure of cemented hip reconstructions. In this work, a numerical study with these two process coupled is presented. Previously uniform bone-cement interface mechanical properties were only considered. In this work, a new approach assuming nonuniform and random bone-cement interface mechanical properties was applied to investigate its effect on cement degradation. This methodology was also applied to simulate and compare the degradation process of the cement and bone-cement interface in three different concepts of design: Exeter, Charnley, and ABG II stems. Nonuniform and random mechanical properties of the bone-cement interface implied a simulation closer to reality. The predicted results showed that the cement deterioration and bone-cement interface debonding is different for each implant depending on the stem geometry. Lower cement deterioration was obtained for the Charnley stem and lower bone-cement interface debonding was predicted for the Exeter stem, while the highest deterioration (cement and bone-cement interface) was produced for the ABG II stem.