Contemporary unicompartmental knee arthroplasty: fixed vs mobile bearing.

Contemporary unicompartmental knee arthroplasty has shown resurgence in use partly because of studies reporting excellent long-term survivorship. Both fixed-bearing as well as mobile-bearing designs have shown comparable results. Fixed-bearing designs, in particular, implants with metal-backed tibial components have shown more consistent long-term survival, whereas fixed bearings with an all-polyethylene tibial component have had mixed results. Similar to the all-polyethylene tibial component designs, mobile-bearing designs have demonstrated mixed results. One concern with mobile bearings is the high rate of complete tibial radiolucent lines. The keys to long-term survival of both fixed and mobile-bearing designs in unicompartmental knee arthroplasty are patient selection, surgical technique, and surgical experience.