Sc. Mantell et al., A PARAMETRIC STUDY OF ACETABULAR CUP DESIGN VARIABLES USING FINITE-ELEMENT ANALYSIS AND STATISTICAL DESIGN OF EXPERIMENTS, Journal of biomechanical engineering, 120(5), 1998, pp. 667-675
To isolate the primary variables influencing acetabular cup and interf
ace stresses, we performed an evaluation of cup lending and clip suppo
rt variables, using a Statistical Design of Experiments (SDOE) approac
h. We developed three-dimensional finite element (FEM) models of the p
elvis and adjacent bone. Cup support variables included fixation mecha
nism (cemented or noncemented), amount of bone support, and presence o
f metal backing. Cup loading variables included head size and clip thi
ckness, cup/head friction, and conformity between the clip and head. I
nteraction between and among variables was determined using SDOE techn
iques. Of the variables tested, conformity, head size, and backing eme
rged as significant influences on stresses. Since initially nonconform
ing surfaces would be expected to wear into conforming surfaces, confo
rmity is not expected to be a clinically significant variable. This in
dicates that head size should be tightly toleranced during manufacturi
ng, and that small changes in head size can have a disproportionate in
fluence on the stress environment. In addition, attention should be pa
id to the use of nonmetal backed clips, in limiting cup/bone interface
stresses. No combination of secondary variables could compensate for,
or oven ide the effect of the primary variables. Based on the results
using the SDOE approach, adaptive FEM models simulating the wear proc
ess may be able to limit their parameters to head size and cup backing
.