title: Mixed-mode failure response of the cement-bone interface.
abstract: Mechanical failure of the cement-bone interface can contribute to clinical loosening of cemented total hip replacements. The conditions that cause loosening are poorly understood, in part, due to a lack of information on the mechanical behavior of the cement bone interface. The purpose of this study was to determine the mechanical behavior of the cement-bone interface due to mixed-mode (combined tension and shear) loading and to develop a failure model for the cement bone interface. Laboratory tests of machined cement-bone test specimens were performed with mixed-mode loading conditions (loading angles of 22.5 degrees, 45 degrees, and 67.5 degrees) to determine the mechanical response in the pre-yield and post-yield state. After accounting for the quantity of interdigitated bone as a covariate, the mixed-mode data were combined with previous tension (0 degrees) and shear data (90 degrees) to develop a failure model for the cement bone interface. The strength of the interface was positively correlated with the quantity of interdigitated bone (r2 = 0.70, 0.53, 0.49, for 22.5 degrees, 45 degrees, and 67.5 degrees, respectively). There was a significant increase in failure strength (P < 0.001) with increasing mixed-mode angle. When all data were incorporated into an elliptical failure criterion, the average error between the actual and predicted strength was 33%. These results can now be incorporated into constitutive models of the cement bone interface to determine the initiation and progression of interface failure in cemented total hip replacements.
authors.affiliation: Department of Orthopedic Surgery, Institute for Human Performance, Upstate Medical University, Syracuse, New York 13210, USA. mannk@mail.upstate.edu
authors.forename: K A
authors.initials: KA
authors.lastname: Mann
authors.forename: R
authors.initials: R
authors.lastname: Mocarski
authors.forename: L A
authors.initials: LA
authors.lastname: Damron
authors.forename: M J
authors.initials: MJ
authors.lastname: Allen
authors.forename: D C
authors.initials: DC
authors.lastname: Ayers
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D001696:Biomechanical Phenomena; D001843:Bone Cements; D001842:Bone and Bones / Q000502:physiology*; D006801:Humans; D008875:Middle Aged; D013314:Stress, Mechanical; D013718:Tensile Strength
chemical_list: D001843:Bone Cements