A total of 397 hips were randomised to receive
Metasul metal-on-metal (MoM), metal-on-conventional polyethylene (MoP)
or ceramic-on-polyethylene (CoP) bearings using a cemented triple-tapered
polished femoral component (MS-30). There were 129 MoM hips in 123
patients (39 male and 84 female, mean age 63.3 years (40.7 to 72.9)),
137 MoP hips in 127 patients (39 male and 88 female, mean age 62.8
years (24.5 to 72.7)) and 131 CoP hips in 124 patients (51 male
and 73 female, mean age 63.9 years (30.6 to 73.8)). All acetabular
components were cemented Weber polyethylene components with the
appropriate inlay for the MoM articulation. Clinical evaluation
was undertaken using the Harris hip score (HHS) and radiological
assessments were made at two, five and seven years. The HHS and radiological
analysis were available for 341 hips after seven years. The MoM
group had the lowest mean HHS (p = 0.124), a higher rate of revision
(p <
0.001) and a higher incidence of radiolucent lines in unrevised
hips (p <
0.001). In all, 12 revisions had been performed in
12 patients: eight in the MoM group (four for infection, four for
aseptic loosening, three in the MoP group (one each of infection,
dislocation and pain) and one in the CoP group (infection). Our findings reveal no advantage to the MoM bearing and identified
a higher revision rate and a greater incidence of radiolucent lines
than with the other articulations. We recommend that patients with
a 28 mm Metasul MoM bearing be followed carefully. Cite this article:
