Vol.:(0123456789) 1 3 European Journal of Orthopaedic Surgery & Traumatology https://doi.org/10.1007/s00590-019-02485-5 ORIGINAL ARTICLE When can I go home after my knee replacement? Factors afecting the duration of in‑hospital stay after knee replacement Vishesh Khanna 1,2  · A. V. Gurava Reddy 1  · Deepesh Daultani 1  · Sukesh Rao Sankineani 1  · Jai Khanna 3  · Adarsh Annapareddy 1  · Krishna Kiran Eachampati 4 Received: 29 April 2019 / Accepted: 26 June 2019 © Springer-Verlag France SAS, part of Springer Nature 2019 Abstract Background Despite a sevenfold decline in the number of postoperative nights (21–3) after a total knee arthroplasty (TKA) over the last four decades, predictors of length of stay (LOS) are not fully understood. We attempted to ascertain these fac- tors by analyzing a large cohort of patients. Methods Prospectively collected data between January 2016 and March 2017 were retrospectively analyzed at our institute. Charts of 1663 consecutive, simple primary unilateral and bilateral TKAs were reviewed for the LOS excluding staggered bilateral, complex primary and revision knees. Statistical analysis: Preoperative variables [demographics, cash/credit status, historical, clinical, laboratory fndings, Knee Society Function Scores and Oxford Knee Scores (OKSs)] were scrutinized by multivariate regression to identify signifcant factors afecting LOS and formulate model equations for patients and health caregivers. Results were incorporated into an iOS application, which was tested for accuracy. Results Among 1524 unilateral and 139 bilateral TKAs, mean LOS was 4.4 and 5.2 days, respectively. Five factors, namely insurance, fexion/hyperextension deformity, preoperative OKS and a rheumatoid etiology, were signifcantly associated with prolonged LOS in unilateral knees. The impact of these independent variables on LOS could be calculated by: For bilateral cases, the only signifcant variable extending LOS was a low preoperative OKS and the equation is given as follows: The iOS-app-predicted LOS and actual LOS were similar (p > 0.05) for 115 prospectively operated knees. Conclusion Poor preoperative OKS, rheumatoid etiology, fexion and hyperextension deformity and delays in insurance afected unilateral TKR LOS, while poor preoperative OKS alone afected LOS in bilateral cases. Keywords Length of stay · Discharge delays · Equations predicting stay · Primary total knee arthroplasty · Insurance delays · Severe deformities Introduction Among close to 300 conditions, knee osteoarthritis (OA) ranks as the 11th most disabling condition worldwide [1]. Evolving surgical and technological refinements have provided patients debilitated with knee OA, an improved quality of life demonstrable by high satisfaction scores following total knee arthroplasty (TKA). Additionally, the emergence of excellent long-term implant survival (99%) after TKA has made it a game changer for clinicians in managing patients with tricompartmental OA [2–4]. LOS = 5.6 -(0.39 × CI)+(0.04 × FFD)-(0.03 × PREOPOKS)+(0.06 × HE)-(0.71 × ET) LOS = 7.71 -(0.15 × PREOPKS) * Vishesh Khanna visheshkhanna85@gmail.com 1 Sunshine Hospitals, Penderghast Road, Opposite Parsi Dharamsala, Paradise, Secunderabad, Telangana 500003, India 2 New Delhi, India 3 San Francisco, CA, USA 4 Maxcure Hospital, Madhapur, Telangana 500081, India