Letter to the Editor on “Mortality and Implant Survival With Simultaneous and Staged Bilateral Total Knee Arthroplasty Experience From the Australian Orthopedic Association National Joint Replacement Registry”.

Abstract

To the Editor: We have read with interest the recent article by Chua et al [1] entitled “Mortality and Implant Survival With Simultaneous and Staged Bilateral Total Knee Arthroplasty Experience From the Australian Orthopedic Association National Joint Replacement Registry.” In this study, patients undergoing staged bilateral total knee replacement (TKR) were at significantly lower risk of death within 30 days of the second procedure than patients undergoing simultaneous bilateral TKR (0.06% vs 0.17%).

We believe this finding is not surprising, as mortality after the first procedure in those intended for bilateral TKR was not taken into account. Unfortunately, their analysis of registry data has no way of identifying patients who fit this latter category. Therefore, the study in its current form is in fact comparing the mortality rates of patients undergoing simultaneous bilateral TKR with a specially selected cohort of patients who have recently survived a unilateral TKR. Furthermore, this last group of patients, by nature, did not suffer any sort of catastrophic non-fatal complication associated with the first TKR which would have rendered them unwilling or unable to undergo a second TKR. Given the known complication rate (∼6%) [2, 3] which may deter subsequent procedures, this is a particularly select cohort.