Factors influencing postoperative length of stay in an enhanced recovery after surgery program for primary total knee arthroplasty

BACKGROUND: Hospital length of stay (LOS) after primary total knee arthroplasty (TKA) has decreased obviously following the implementation of enhanced recovery after surgery (ERAS) program in the last few years. However, there are still some patients that cannot be discharged at early time for a variety of reasons, and it is necessary to explore factors leading to prolonged LOS. Therefore, the purpose of this study was to identify the complete preoperative, perioperative, and postoperative factors associated with prolonged postoperative LOS (PLOS) after primary TKA in a detailed ERAS program. METHODS: In a consecutive series from July 2015 to March 2017, all patients who underwent unilateral elective primary TKA were included in the retrospective study. A PLOS greater than 3 days was considered a prolonged PLOS. Multivariable logistic regression analysis was performed to identify patient characteristics and relevant preoperative, perioperative, and postoperative variables that were associated with prolonged PLOS and postoperative complications. RESULTS: A total of 241 patients were included with a mean PLOS of 3.8 days. Prolonged PLOS was significantly associated with preoperative valgus deformity of the knee (OR 4.95, 95%CI 1.56–15.77, P = 0.007), increased serum level of interleukin-6 on postoperative day 1 (OR 1.01, 95%CI 1.00–1.03, P = 0.039), increased visual analogue scale pain score and serum level of C-reactive protein on postoperative day 3 (OR 2.56, 95%CI 1.28–5.13, P = 0.008; OR 1.01, 95%CI 1.00–1.03, P = 0.019), increased day to achieve 90° active knee flexion after surgery (OR 2.19, 95%CI 1.27–3.79, P = 0.005), and postoperative wound complications (OR 8.58, 95%CI 2.10–35.03, P = 0.003) and other minor complications (OR 6.04, 95%CI 2.40–15.19, P < 0.001). Preoperative pulmonary infection (OR 2.75, 95%CI 1.20–6.28, P = 0.016), American Society of Anesthesiologists score 3/4 (OR 2.14, 95%CI 1.01–4.52, P = 0.046), and utilization of catheter after surgery (OR 2.53, 95%CI 1.23–5.19, P = 0.012) were significantly associated with postoperative complications. CONCLUSIONS: Multiple factors were associated with prolonged PLOS and postoperative complications after TKA in the ERAS program. It is important to recognize all the factors to try to maximize the use of medical resources and ultimately optimize the care of our patients.