The role of routine postoperative laboratory tests following hip hemiarthroplasty for an elderly femoral neck fracture

Performing postoperative laboratory tests following joint arthroplasty is a regular practice. However, the role of routine postoperative laboratory tests in primary hip arthroplasty is currently in doubt. This study aimed to assess the role of routine postoperative laboratory tests for femoral neck fractures in elderly patients who underwent hip hemiarthroplasty and to evaluate the risk factors for postoperative laboratory testing abnormalities and related interventions. This retrospective study reviewed 735 consecutive patients with femoral neck fractures (FNFs) who underwent hip hemiarthroplasty at a single tertiary academic organization. Patient characteristic features and laboratory testing values were recorded. Logistic regression models were calculated to identify risk factors. A total of 321 elderly patients (> 75 years of age) were ultimately enrolled for analysis. Abnormal postoperative laboratory tests were found in 265 patients (82.6%). Only a minority of the included patients (7.5%) needed medical intervention to treat postoperative laboratory testing abnormalities. Multivariate logistic regression analysis reported that a higher Charlson comorbidity index (CCI) (P = 0.03), abnormal preoperative haemoglobin level (P < 0.01), higher intraoperative blood loss (P < 0.01) and less frequent tranexamic acid use (P = 0.05) were risk factors for abnormal postoperative laboratory tests. Furthermore, a higher CCI has been identified as a risk factor for patients needing clinical interventions related to laboratory abnormalities. Because 92.5% of laboratory tests did not influence postoperative management, the authors suggest that routine laboratory tests after hip hemiarthroplasty for FNFs are less instructive for the majority of elderly patients. Nevertheless, for patients with identified risk factors, postoperative laboratory tests are still required to identify the abnormalities that need to be managed.