title: The influence of the strength of bone on the deformation of acetabular shells: a laboratory experiment in cadavers.
abstract: Concerns have been raised that deformation of acetabular shells may disrupt the assembly process of modular prostheses. In this study we aimed to examine the effect that the strength of bone has on the amount of deformation of the acetabular shell. The hypothesis was that stronger bone would result in greater deformation. A total of 17 acetabular shells were inserted into the acetabula of eight cadavers, and deformation was measured using an optical measuring system. Cores of bone from the femoral head were taken from each cadaver and compressed using a materials testing machine. The highest peak modulus and yield stress for each cadaver were used to represent the strength of the bone and compared with the values for the deformation and the surgeon's subjective assessment of the hardness of the bone. The mean deformation of the shell was 129 µm (3 to 340). No correlation was found between deformation and either the maximum peak modulus (r² = 0.011, t = 0.426, p = 0.676) or the yield stress (r² = 0.024, t = 0.614, p = 0.549) of the bone. Although no correlation was found between the strength of the bone and deformation, the values for the deformation observed could be sufficient to disrupt the assembly process of modular acetabular components.
authors.affiliation: Newcastle University, Stephenson Building, Claremont Road, Tyne and Wear NE1 7RU, UK.
authors.forename: M C
authors.initials: MC
authors.lastname: Bone
authors.affiliation: CeramTec GmbH, 73207 Plochingen, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Dold
authors.affiliation: CeramTec GmbH, 73207 Plochingen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Flohr
authors.affiliation: CeramTec GmbH, 73207 Plochingen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Preuss
authors.affiliation: Newcastle University, Stephenson Building, Claremont Road, Tyne and Wear NE1 7RU, UK.
authors.forename: T J
authors.initials: TJ
authors.lastname: Joyce
authors.affiliation: University of Aberdeen, IMS Building, Foresterhill, Aberdeen AB25 2ZD, UK.
authors.forename: R M
authors.initials: RM
authors.lastname: Aspden
authors.affiliation: Freeman Hospital, Newcastle Upon Tyne NE7 7AH, UK.
authors.forename: J
authors.initials: J
authors.lastname: Holland
authors.affiliation: Freeman Hospital, Newcastle Upon Tyne NE7 7AH, UK.
authors.forename: D
authors.initials: D
authors.lastname: Deehan
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D001672:Biocompatible Materials; D002102:Cadaver; D019245:Compressive Strength; D005260:Female; D005269:Femur / Q000601:surgery; D005270:Femur Head / Q000502:physiology*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008422:Materials Testing; D008875:Middle Aged; D014025:Titanium
chemical_list: D001672:Biocompatible Materials; D014025:Titanium
keywords: Acetabular shell deformation; acetabular component; bone strength; cadaver; optical measurement system