The optimal interval between staged bilateral total knee arthroplasty (STBTKA) is unclear. Studies have reported STBTKA being performed at the same admission, with a seven day interval. The safety and outcomes of patients submitted to same-admission STBTKA (SA-STBTKA) are questionable and need further investigation.
A prospective non-randomized study was performed to compare the early postoperative outcomes, systemic complications, and surgical-related complications between the first and second knees, as well as between SA-STBTKA and STBTKA groups. From July 2018 to November 2019, a total of 430 patients were recruited. Analyzed parameters included the Knee Society score (KSS), Knee Society functional score (KSFS), range of motion (ROM), Western Ontario and McMaster Universities Arthritis Index (WOMAC) pain score, WOMAC stiffness score, and WOMAC score for daily life difficulty.
Pre-operatively, the demographic data and functional scores were not significantly different between the two groups. The KSS, WOMAC pain score, and WOMAC stiffness score of the second knee in the STBTKA group were significantly better than those of the first knee. A total of 426 patients completed the last follow-up one  year after surgery, and the post-operative functional scores were not significantly different between the two groups and between the two knees within the same group. Before the second operation, more systemic complications were identified in the SA-STBTKA group, while the rate of surgical complication was not significantly different when compared to STBTKA patients.
With equivalent post-operative function and a higher frequency of minor complications, SA-STBTKA should be cautiously selected as a treatment option for bilateral osteoarthritis.