Length of stay after introduction of a new total knee arthroplasty (TKA)—results of a German retrospective database analysis

Background: Although total knee arthroplasty (TKA) procedures are increasing, patient satisfaction is still inferior compared to total hip arthroplasty. The ATTUNE® Knee System was designed to reduce pain and improve function, leading to greater patient satisfaction and decreased resource utilization in TKA. The objective of this study was to compare length of stay (LOS) of TKA with ATTUNE knee versus LCS® knee implants. Methods: A retrospective chart review analysis in a German center was conducted between 2008 and 2016. All patients without prior ipsilateral knee operation, treated with a cemented LCS or ATTUNE knee were included. Endpoints captured included gender, age, availability of home support, prior contralateral TKA, ASA grade and LOS. Statistical analyses included chi-squared test for differences in patient demographics and Welch two-sample t-test for difference in LOS. Results: Mean LOS in the ATTUNE Knee group (N=85) was 8.3 days (SD: 1.79) compared to 10.4 days (SD: 1.91) in the LCS knee group (N=85). No significant differences in gender, age, availability of home support, prior contralateral TKA, or ASA grade between both cohorts were observed. The 2.1 days reduction was statistically significant (P<0.001; 95%CI: 2.7-1.6). A sensitivity analysis outlined the impact of the study duration: even when assuming that 1.3 days reduction resulted from the observed national LOS decrease, the remaining 0.8 reduction in days LOS reduction was still significant (P<0.01). Conclusion: When comparing two cohorts with similar sociodemographic and medical factors, LOS of ATTUNE knee patients was 2.1 days shorter than patients treated with the LCS knee.