The majority of failed UKAs are revised to TKA. If appropriate indications are met, liner exchange or revision to another UKA are possible, but in general, these procedures have poor longevity and a higher failure rate. Revisions of failed UKA to TKA appear to have a slightly inferior outcome when compared to primary TKA but better outcome than revision TKA. The mechanism of failure and the potential challenges at revision are influenced by the type of implant used, the surgical technique at the time of primary UKA, and patient-related factors. Most revisions can be accomplished using primary TKA systems. However, a system that allows the use of augments, stems, and/or metaphyseal sleeves or cones should be available.