Influencing factors of hidden blood loss after primary total hip arthroplasty through the posterior approach: a retrospective study

BACKGROUND: Total hip arthroplasty (THA) is an excellent treatment for the end-stage hip disease, and perioperative blood management strategies have been effectively applied to this procedure. However, many patients still experience anemia after the operation, which is usually overlooked by orthopedic surgeons due to the hidden blood loss (HBL) in the perioperative period. Therefore, the objective of this study was to evaluate HBL in patients undergoing primary THA using the posterior approach and to explore its influencing factors. METHODS: A retrospective analysis of 707 patients who underwent primary THA through the posterior approach was conducted in our hospital from January 2020 to January 2022. By applying Gross’s and Nadler’s formula, the HBL was calculated. Six quantitative variables (age, body mass index, surgical duration, albumin loss, preoperative hemoglobin, and hemoglobin loss) as well as four qualitative variables (gender, American Society of Anesthesiologists class, major preoperative diagnosis, and hypertension) of patients were analyzed using multivariate linear regression. RESULTS: The HBL was recorded at 700.39 ± 368.59 mL. As a result of multivariate linear regression analysis, it was determined that body mass index, surgical duration, and hemoglobin loss were all significant risk factors for HBL, whereas preoperative hemoglobin was considered a protective factor. It has been demonstrated that HBL is not significantly correlated with age, albumin loss, gender, ASA class, or major preoperative diagnosis, but it also did not differ from HBL by hypertension. CONCLUSIONS: Hidden blood Loss (HBL) in patients after primary total hip arthroplasty (THA) using the posterior approach is large and significant. When optimizing the perioperative management of THA, orthopedic surgeons should keep in mind HBL and its influencing factors, especially for patients with high body mass indexes, long surgical durations, and low preoperative hemoglobin levels. TRIAL REGISTRATION: This study was registered in the Chinese Clinical Trial Registry (ChiCTR2100053888) in 02/12/2021, http://www.chictr.org.cn.