Patient reported outcomes in three hundred and twenty eight bilateral total knee replacement cases (simultaneous versus staged arthroplasty) using the Oxford Knee Score

Despite bilateral knee replacement being frequently performed, little data is available to inform on the relative outcomes of each knee for individual patients. The purpose of this study was to compare these outcomes in a series of bilateral total knee replacements (TKRs) performed either simultaneously or at a staged interval. We compared outcomes measured by the Oxford Knee Score (OKS; /48) in a series of 656 bilateral TKRs (328 patients). One hundred and fifty-six TKRs were simultaneous and 500 TKRs staged. Of the staged patients, in 164 (65.6 %) the post-operative OKS in their second TKR matched the first, it was worse in 57 (22.8 %) and better in 29 (11.6 %). The trend was towards a worse OKS in the second staged TKR (p = 0.003). Mean improvement was similar in simultaneous cases to the first staged TKR (24.3 vs. 24.0; p = 0.883) but significantly less in second staged TKRs (20.2; p < 0.001) due to higher pre-operative scores. Individual patients attained a comparable post-operative score in both their knees, independent of age, pre-operative function and the duration of any staging interval.