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· DOS Abstracts
Is newer better? Revision risk of total hip arthro-
plasty with the newer Echo Bimetric stem compared
to the preceding Bimetric stem
Claus Varnum, Per Hviid Gundtoft, Lasse Enkebølle Rasmussen, Per Kjærsgaard-
Andersen
Department of Orthopaedic Surgery, Vejle Hospital; Department of Orthopae-
dic Surgery, Kolding Hospital
Background:
In 2010, the cementless Echo Bimetric hip stem was introduced
in Denmark. This stem was a redesigned version of the cementless Bimetric
stem with a smooth, tapered stem tip; distal extension of the circumferential
porous plasma splay; and 2 metaphyseal geometeric options.
Purpose / Aim of Study:
We aimed to compare the 5-years revision risk of
the total hip arthroplasty (THA) in patients operated with the cementless Echo
Bimetric stem and its predecessor, the Bimetric stem.
Materials and Methods:
Based on data from the Danish Hip Arthroplasty Reg-
ister, all cementless THAs with the cementless Echo Bimetric or Bimetric stem
were identified. Patients were followed until revision, death, emigration, or end
of study period (May 1, 2017). We performed regression with the pseudo-
value approach with death as a competing risk to estimate the relative risk (RR)
of any revision with 95% confidence intervals at 5–years follow-up, and adjust-
ments were made for sex, age, primary diagnosis femoral head size, and dura-
tion of surgery.
Findings / Results:
A total of 28,223 cementless THAs were identified: 2,307
(8%) had the Echo Bimetric stem and 25,916 (92%) the Bimetric stem. The
mean follow-up was 2.8 (2.7-2.9) for Echo Bimetric and 7.1 (7.1-7.2) years
for Bimetric. At 5-years, the cumulative incidence for any revision was 4.4%
(3.1-6.3) for Echo Bimetric and 4.8% (4.6-5.1) for Bimetric. The adjusted RR
for any revision of the Echo Bimetric stem was 0.92 (0.75-1.13) compared to
the Bimetric stem. Also the adjusted RR for revision due to aseptic loosening of
the stem was similar in the two groups (p=0.96).
Conclusions:
There was no difference in revision risk between the Echo Bi-
metric and the Bimetric stem in THA in this study period. Whether the Echo
Bimetric stem is superior to the Bimetric stem on the longer term remains to be
established.
No conflicts of interest reported
108.