Db. Bennett et al., Movement loci of selected points on the femoral head for individual total hip arthroplasty patients using three-dimensional computer simulation, J ARTHROPLA, 15(7), 2000, pp. 909-915
Wear of ultra-high-molecular-weight polyethylene (UHMWPE) and the subsequen
t adverse tissue reaction to the wear particles has been cited as the predo
minant problem affecting total joint arthroplasties. Wear of the UHMWPE ace
tabular cup in total hip arthroplasties (THAs) is influenced by the sliding
distance and direction of individual points on the femoral head, which has
as yet been ascertained only for normal subjects. This study seeks to dete
rmine the trajectory of specified points on the femoral head for individual
THA patients and the distances traversed by these points. A computer progr
am was designed to use gait data from THA patients to simulate the motion o
f these points. Gait analysis was performed on 19 THA patients at a period
of 5 years after operation. The orientation of the acetabular cup was ascer
tained from radiographs to determine the position of the points on the head
most involved in the wear process. The loci of the points differed widely
in size, shape, and direction between subjects. The largest average distanc
e traversed was 140% greater than the smallest average distance traversed.
Shorter longitudinal paths would tend to cause less wear than larger, wider
paths, which cross a greater number of adjacent paths.