title: Photoelastic comparison of strains in the underlying glenoid with metal-backed and all-polyethylene implants.
abstract: An alteration in the stress and strain environment following arthroplasty is believed to lead to bone remodeling, which can trigger implant loosening and subsequent failure. Bone remodeling, while well-studied in hip arthroplasty, has received less attention in total shoulder replacement. This study examines differences in strain states between intact glenoids and following replacement with an uncemented metal backed keeled component and a cemented all polyethylene pegged component with the same articular geometry, using the photoelastic method. Strain measurements were taken in glenoids before and after implantation under 4 loading conditions corresponding to 4 abduction angles: 0 degrees, 30 degrees, 60 degrees, and 90 degrees. Shear strains increased at most locations following reconstruction with both of the implants. Uncemented, keeled metal backed implants produced areas of higher cortical shear strains compared to cemented, all PE pegged implants.
authors.affiliation: Surgical & Orthopaedic Research Laboratories, Prince of Wales Hospital, University of New South Wales, Sydney, Australia. m.pelletier@unsw.edu.au
authors.forename: Matthew H
authors.initials: MH
authors.lastname: Pelletier
authors.forename: Andrew
authors.initials: A
authors.lastname: Langdown
authors.forename: R Mark
authors.initials: RM
authors.lastname: Gillies
authors.forename: David H
authors.initials: DH
authors.lastname: Sonnabend
authors.forename: William R
authors.initials: WR
authors.lastname: Walsh
mesh_terms: D000368:Aged; D019643:Arthroplasty, Replacement / Q000009:adverse effects*; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D016723:Bone Remodeling / Q000502:physiology*; D002102:Cadaver; D006801:Humans; D007595:Joint Prosthesis; D008875:Middle Aged; D020959:Polyethylene; D011475:Prosthesis Failure; D012540:Scapula / Q000502:physiology* / Q000503:physiopathology*; D033081:Shear Strength; D012785:Shoulder Joint / Q000503:physiopathology*
chemical_list: D001672:Biocompatible Materials; D020959:Polyethylene