DOS Kongressen 2014 ·
55
Revision risk of cementless metal-on-metal total hip
arthroplasty is influenced by component brand
Claus Varnum, Alma B. Pedersen, Mäkelä Keijo, Leif Ivar Havelin,
Johan Kärrholm, Søren Overgaard
Orthopaedic department, Vejle Hospital; Department of clinical epide-
miology, Aarhus University Hospital; Department of Orthopaedics and
Traumatology, Turku University Hospital, Finland; The Norwegian Arthroplasty
Register, Department of Orthopedic Surgery, Haukeland University Hospital,
Bergen, Norway; Institute of Clinical Sciences, Department of Orthopaedics,
Sahlgrenska University Hospital, Gothenburg, Sweden; Department of
Orthopaedic Surgery and Traumatology, Odense University Hospital
Background:
There are several concerns for the use of metal-on-metal (MoM)
bearings in total hip arthroplasty (THA) especially for certain brands of MoM
components due to increased revision rates.
Purpose / Aim of Study:
We aimed to investigate the 6-year revision risk of
cementless stemmed MoM THAs in a population-based follow-up study from
the Nordic Arthroplasty Registry Association (NARA).
Materials and Methods:
In the NARA database, we identified 85,371 cement-
less stemmed primary THAs operated from 2002 to 2010. Metal-on- polyeth-
ylene (MoP) THA was used as reference, and only patients operated with MoM
or MoP bearings were included. In total, 32,678 patients were included. At 6
years follow-up, the adjusted relative risk (aRR) for any revision with 95% con-
fidence intervals (CI) was assessed by the use of regression with the pseudo-
value approach and modelled with death as competing risk.
Findings / Results:
11,567 patients (35%) had MoM and 21,111 (65%) had
MoP THAs. The aRR of any revision for MoM was 1.49 (CI: 1.30-1.71). For
different brands of acetabular cups in MoM THA, higher RR of any revision was
found for the ASR cup (n=759; aRR 6.38, CI: 4.99-8.15), the Conserve Plus
cup (n=478; aRR 1.70, CI: 1.14-2.54), and ”other” cups (n=351; aRR 2.38, CI:
1.45-3.92). No difference in RR of any revision was found for the Recap, M2a,
Pinnacle, Birmingham, and Durom cups compared to MoP THA. After exclusion
of the 759 patients having the ASR acetabular component, the aRR of any revi-
sion was 1.12 (CI: 0.97-1.30) for MoM compared to MoP THA.
Conclusions:
The aRR of any revision at 6 years follow- up was 49% higher
for MoM compared to MoP THA. After exclusion of the ASR cup, the aRR of
any revision was 12% higher for MoM THA – although this was not significant.
Based on recent reports, we may expect increasing revision rates of MoM THAs
with longer follow-up.
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