Document Detail


Differences in long-term fixation between mobile-bearing and fixed-bearing knee prostheses at ten to 12 years' follow-up: A single-blinded randomised controlled radiostereometric trial.
MedLine Citation:
PMID:  23015562     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
This single-blinded randomised controlled trial investigated whether one design of mobile-bearing (MB) total knee replacement (TKR) has any advantage over a fixed-bearing (FB) design on long-term fixation as measured by radiostereometry. The amount of wear underneath the mobile bearing was also evaluated. A series of 42 knees was randomised to MB or FB tibial components with appropriate polyethylene inserts and followed for between ten and 12 years, or until the death of the patient. The polyethylene in the MB group was superior in that it was gamma-irradiated in inert gas and was calcium-stearate free; the polyethylene in the FB group was gamma-irradiated in air and contained calcium stearate. In theory this should be advantageous to the wear rate of the MB group. At final follow-up the overall mean migration was 0.75 mm (sd 0.76) in the MB group and 0.66 mm (sd 0.4) in the FB group, with the FB group demonstrating more posterior tilt and the MB group more internal rotation. In the FB group there was one revision for aseptic loosening, but none in the MB group. There were no significant differences in clinical or radiological scores. For the MB group, the mean linear wear rate on the under-surface was 0.026 mm/year (sd 0.014). This was significantly smaller than the wear rate of 0.11 mm/year (sd 0.06) in the MB between femur and polyethylene (p < 0.001). Nevertheless, even in a best-case setting the mobile bearings of this TKR design had no apparent advantage in terms of fixation over the FB knee prosthesis at ten to 12 years. The wear underneath the mobile bearing was small and is unlikely to be clinically relevant.
Authors:
B G Pijls; E R Valstar; B L Kaptein; R G H H Nelissen
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of bone and joint surgery. British volume     Volume:  94     ISSN:  0301-620X     ISO Abbreviation:  J Bone Joint Surg Br     Publication Date:  2012 Oct 
Date Detail:
Created Date:  2012-09-27     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0375355     Medline TA:  J Bone Joint Surg Br     Country:  England    
Other Details:
Languages:  eng     Pagination:  1366-71     Citation Subset:  AIM; IM    
Affiliation:
Leiden University Medical Center, Department of Orthopaedics, P.O. Box 9600, Postzone J-11-S 2300 RC Leiden, The Netherlands.
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