[Translated article] Determining factors on length of stay in primary total knee arthroplasty patients using enhanced recovery protocol after surgery (ERAS) pathway.

Introduction: There is an increase in degenerative arthropathies because of the increase in the longevity of world's population, making primary knee arthroplasties a procedure to recover quality of life without pain. There are factors associated with the length of hospital stay after this procedure.

Objective: To determine the risk factors influencing the hospital stay during the postoperative period of patients undergoing primary total knee arthroplasty with an enhanced recovery after surgery protocol (ERAS).

Methods: A retrospective study is carried out on patients undergoing primary total knee arthroplasty at an University Hospital in the period 2017-2020 using the ERAS protocol, during which 957 surgeries were performed.

Results: Average age of 71.7±8.2years, 62.4% were women and the 77.3% were classified as ASA II. The significantly associated factors to an increased length of stay are: age (p=.001), ASA scale (p=.04), day of surgery (p<.001), blood transfusion (p<.001), postoperative haemoglobin level at 48-72h (p<.001), the time of first postoperative mobilisation to ambulate and climb stairs (p<.001), the need for analgesic rescues (p=.003), and the presence of postoperative nausea and vomiting (p=.008).

Conclusions: There are statistically significant and clinically relevant factors associated with hospital stay. Determining these factors constitutes an advantage in hospital management, in the development of strategies to improve and optimise the quality of care and available health resources.