Modelling debonded stem–cement interface for hip implants: effect of residual stresses

Measurement of transient and residual stresses during polymerization of bone cement for cemented hip implants

“…1) of cylindrical shape, similar to previous experimental studies (Ahmed et al, 1982a;Nuñ o and Amabili, 2002;Roques et al, 2004), is used. The bone cylinder (40 mm external and 29 mm internal diameter) is 158 mm long; its distal part allows the stem to be centered during insertion resulting in a 5-mm bone cement thickness.…”

“…Debonding of the stem-cement interface and damage accumulation in the cement may lead to long-term failure of fixation (Jasty et al, 1991;Lennon and Prendergast, 2002;Orr et al, 2003). Polymethylmethacrylate (PMMA) or bone cement is used for the fixation of the prosthesis to the bone; it completely fills the space between the implant and the bone and does not chemically bond with the implant or the bone (Nuñ o and Amabili, 2002). The curing process of bone cement is an exothermic reaction where cement undergoes volumetric changes (Ahmed et al, 1982a;Muller et al, 2002).…”

“…The curing process of bone cement is an exothermic reaction where cement undergoes volumetric changes (Ahmed et al, 1982a;Muller et al, 2002). During this complex phenomenon, porosity and stresses at both interfaces and inside bulk cement are observed (Ahmed et al, 1982a;Bishop et al, 1996;Gilbert et al, 2000;Mann et al, 2007;Nuñ o and Amabili, 2002). Numerous studies (Bishop et al, 1996;Damron et al, 2006;Iesaka et al, 2003;Wang et al, 2003) have shown significant reduction of stem-cement interfacial porosity by stem pre-heating.…”

“…Very few experimental studies (Ahmed et al, 1982a;Nuñ o and Amabili, 2002;Roques et al, 2004) have assessed the stresses generated during PMMA polymerization. Ahmed et al (1982a) indirectly quantified the cement residual stresses on four specimens.…”

Aseptic loosening, not only a question of wear: A review of different theories

“…In hips, the stresses between stem implant and cement are mostly shear, whereas compressive stress forces prevail in the acetabulum. In polished stems, where debonding occurs more easily, the forces transmitted to the cement are different from those in precoated or blasted stems designed to avoid debonding (Lu and McKellop 1997, Lennon and Prendergast 2001, Nuno and Amabili 2002. This may affect the production of cement wear particles, resulting in a different size distribution as well as a different effective joint space for distribution of the particles.…”