Fixed-Bearing Unicompartmental Knee Arthroplasty
…In appraising the literature, however, it is important to distinguish between mobile-bearing and fixed-bearing unicompartmental implants. Mobile-bearing implants have a fully congruent articulation that moves freely on a polished tibial baseplate, and the theory of this design has been previously published. Fixed-bearing implants have a relatively nonconforming articular surface, which can be inserted as an all-polyethylene tibial component, or as a non-modular or modular metal-backed tibial component. Proponents of mobile-bearing unicompartmental implants believe this design has improved wear characteristics over fixed-bearing implants, and thus may offer a survival advantage in the long-term…
…The reality is that both designs have demonstrated excellent ten-year survivorship free of revision…
…n summary, unicompartmental knee arthroplasty remains an excellent treatment alternative for osteoarthritis confined to the medial or lateral part of the knee joint. Fixed-bearing implants have been shown to provide good pain relief and restoration of function, and have reproducibly demonstrated excellent survivorship into the second decade. This author makes the case for a fixed-bearing over a mobile-bearing implant because they are technically easier, avoid the complication of bearing dislocation, are more versatile, and less expensive.
Douglas Naudie, M.D., FRCSC
Assistant Professor, University of Western Ontario
London, ON