Effect of cementless acetabular cup geometry on strain distribution and press-fit stability.
Use of cementless acetabular cups, which are slightly larger than the reamed acetabulum, can provide press-fit stability without screws; however, the ideal cup geometry to maximize stability is not clear. Acetabular strain distribution, deformation, and implant stability were studied using an axisymmetric finite-element model, and mechanical stability was assessed by testing lever-out and extraction forces required to displace different cup geometries from foam bones. The implants tested included four nonhemispheric cup geometries and 1- and 2-mm oversized hemispheric geometries. A nonhemispheric cup that provides a gradual transition from a hemisphere at the dome to a larger peripheral dimension appears to maximize peripheral strains and implant stability without increasing overall acetabular deformation as much as a larger oversized hemispheric cup.
Ries
M D
MD
Mary Imogene Bassett Hospital, Cooperstown, New York 13326, USA.
Harbaugh
M
M
Shea
J
J
Lambert
R
R
D000077:Acetabulum; D001696:Biomechanical Phenomena; D006622:Hip Prosthesis; D006801:Humans; D011474:Prosthesis Design