Perceptions of the difficulty and outcome of unicompartmental knee arthroplasty revision (rev-UKA) vary. We analyzed differences
in the complexity, cost, and survival of rev-UKAs compared with revision TKAs (rev-TKA). One hundred eighty knee arthroplasty
revisions (68 rev-UKAs/112 rev-TKAs), defined as a minimum of tibial or femoral component revision, were identified from a
community joint registry of 7587 knee implants performed between 1991 and 2005. Four of 68 rev-UKAs (5.9%) were revised a
second time, whereas seven of 112 rev-TKAs (6.3%) were rerevised. Rev-TKA was predictably more complex than rev-UKA based
on the proxies of operative time, use of modular augmentation and stems, and polyethylene liner thickness. Thirty-nine of
68 rev-UKAs (57%) had no form of augmentation and were revised as primary TKAs. There were more rev-TKAs than rev-UKAs with
an implant cost greater than
$5200 (42% versus 12%) and hospital charges greater than $5200 (42% versus 12%) and hospital charges greater than 33,000 (48% versus 25%). We found no
difference in survival between the groups. Although rev-UKAs had less surgical complexity and bone loss at the time of revision
compared with rev-TKAs, we were unable to show improved survival of rev-UKAs compared with rev-TKAs. Rev-UKAs were associated
with lower implant costs and hospital charges compared with rev-TKAs.
Level of Evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest,
patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
Each author certifies that his or her institution has approved the reporting of these cases, that all investigations were
conducted in conformity with ethical principles of research, and that informed consent for participating in the study was
obtained.