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Randomized Controlled Trial
. 2015 Apr;86(2):208-14.
doi: 10.3109/17453674.2014.968476. Epub 2014 Oct 3.

Mobile- vs. fixed-bearing total knee replacement

Michael Tjørnild  1 , Kjeld Søballe, Per Møller Hansen, Carsten Holm, Maiken Stilling
Affiliations
Randomized Controlled Trial

Mobile- vs. fixed-bearing total knee replacement

Michael Tjørnild et al. Acta Orthop. 2015 Apr.

Abstract

Background and purpose: It is unclear whether mobile-bearing (MB) total knee arthroplasties reduce the risk of tibial component loosening compared to fixed-bearing (FB) designs. This randomized study investigated implant migration, periprosthetic bone mineral density (BMD), and patient-reported outcomes (Oxford knee score)-all at 2 years-for the P.F.C. Sigma Cruciate Retaining total knee arthroplasty.

Patients and methods: 50 osteoarthritis patients were allocated to either FB or MB tibial articulation.

Results and interpretation: At 2 years, the mean total translation (implant migration) was higher for the FB implant (0.30 mm, SD 0.22) than for the MB implant (0.17 mm, SD 0.09) (p = 0.04). BMD decreased between baseline and 1-year follow-up. At 2-year follow-up, BMD was close to the baseline level. The knee scores of both groups improved equally well. The FB tibial implant migrated more than the MB, but this was not clinically significant. The mobile polyethylene presumably partly absorbs the force transmitted to the metal tibial tray, thereby reducing micromotion.

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Figures

Figure 1.
Figure 1.
CONSORT 2010 flow diagram.
Figure 2.
Figure 2.
DXA scans showing implant detection, bone borders, and regions of interest (ROIs). A. Anterior/posterior view. B. Lateral view.
Figure 3.
Figure 3.
2-year RSA results. Error bars show SD.
Figure 4.
Figure 4.
Oxford knee score (min = 12, max = 48). Error bars show SD.
See this image and copyright information in PMC

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