Simultaneous bilateral TKA in the context of fast track surgery - Do patients meet discharge criteria as anticipated?

BACKGROUND: The efficacy and safety of enhanced recovery after surgery (ERAS) protocols for patients undergoing total knee arthroplasty (TKA) have been generally proven. Previous studies investigating patients undergoing simultaneous bilateral TKA (SBTKA) focused on complications, mortality, and pain and did not examine patients' functional limitations. Therefore, the aim of this study was to investigate to what extent patients undergoing SBTKA are able to meet functional discharge criteria originally designed for their counterparts undergoing unilateral TKA (UTKA) in an ERAS setting. MATERIALS AND METHODS: All patients who received primary SBTKA between June 2015 and December 2018 were included in this retrospective analysis. For comparison, UTKA patients were matched 1:1 to SBTKA patients using Propensity Score Matching based on age, gender, and BMI. The times to achieving the rehabilitation checkpoints of walking 150 m, walking a flight of stairs, and 90° knee flexion were evaluated. RESULTS: 63 (SBTKA group) and 64 (UTKA group) patients were included. Due to the Propensity-Score-Matching there were no differences regarding age, gender, and BMI. The mean length of stay (LOS) was 9.1 days in the SBTKA and 7.6 days in the UTKA group (p = 0.003). On average, it took SBTKA patients 5.4 days to achieve an uninterrupted walking distance of at least 150 m, while it took UTKA patients 4.1 days (p < 0.001). Mean time to walking a flight of stairs was 6.3 days for SBTKA patients and 4.7 days for UTKA patients (p < 0.001). 90° flexion was achieved after 4.1 days by SBTKA patients and 3.5 days by UTKA patients (p = 0.241). CONCLUSION: The vast majority of SBTKA patients were able to achieve functional discharge criteria within their inpatient stay when allowed about 30% extra time. Therefore, functional discharge criteria in ERAS protocols designed for UTKA can be considered appropriate for SBTKA patients. LEVEL OF EVIDENCE: Therapeutic Level III.