Patient source
We performed a retrospective analysis of prospectively collected data on 80 patients (90 hips) with nontraumatic avascular necrosis of the femoral head who underwent total hip arthroplasty (THA) via the direct anterior approach (DAA) between October 2017 and October 2018. Patients were excluded if they had the following: (1) bilateral THA (10 patients); (2) incomplete radiographic or clinical data (0 patients); (3) follow-up time less than 3 months (0 patients). After applying the exclusion criteria, 70 patients (70 hips) qualified for the study.
Patients were divided into two groups: TXA group (39 patients received 1.5 g TXA intravenously) and control group (31 patients did not receive TXA). This study was approved by the ethics committee of Affiliated Hospital of Xuzhou Medical University (no. 20170829). All methods were performed in accordance with the relevant guidelines and regulations, and all patients gave informed consent.
Study setting
All surgeries were performed by the senior author (Z.G.C) using cementless THA via DAA. All patients received general anesthetic and the same design of the femoral stem (CLS stem; Zimmer, Warsaw, USA) and acetabular cup (Trilogy; Zimmer, Warsaw, USA). We did not use a wound drainage after the procedure. In the TXA group, TXA was given as a 1.5 g intravenous infusion 10 min prior to incision; the control group did not receive TXA.
All patients were managed with a similar perioperative regimen, including intravenous prophylactic antibiotics, prophylaxis against venous thrombosis, and postoperative pain control.
Patients were transfused if their postoperative hemoglobin level was below 70 g/L or if the patient had a hemoglobin above 70 g/L and below 100 g/L but poor mental status, palpitation, or pale complexion. All patients underwent deep vein ultrasound of the lower limbs 1 week postoperatively to detect thrombosis.
Data collection
Data were collected on patient characteristics including sex, age, body mass index (BMI), preoperative hemoglobin (HB), preoperative hematocrit (HCT), and American Society of Anesthesiologists (ASA) classification. HB and HCT levels were also measured at each timepoint on postoperative days 1 and 3. Operative time, transfusion rate, postoperative HB drop, postoperative length of hospital stays (LHS), and Harris hip score (HHS) were recorded. Total blood loss and pulmonary blood volume (PBV) were calculated according to the Gross and Nadler equation [16, 17]. The discharge criteria for patients with THA in our hospital are as follows: (1) stable vital signs, (2) good mental and physical status, (3) no nausea/vomiting, (4) pain control, and (5) no redness, swelling, or exudate from the incision.
PBV = k1 × height3 (meters) + k2 × weight (kilograms) + k3. k1 = 0.3669, k2 = 0.03219, and k3 = 0.6041 for men; and k1 = 0.3561, k2 = 0.03308, and k3 = 0.1833 for women.
Total red blood cell volume loss = PBV × (Hctpre − Hctpost), Hctpre = initial preoperative Hct level, Hctpost = Hct of third postoperative day.
Total blood loss = 1000 × total red blood cell volume loss/(average of Hctpre and Hctpost).
Postoperative HB drop = HBpre – HBpost-3, HBpre = initial preoperative HB level, HBpost-3 = HB of third postoperative day.
Obvious blood loss = intraoperative blood loss + postoperative blood loss.
Hidden blood loss = total blood loss − obvious blood loss.
Statistical methods
All the statistical analyses were performed using IBM SPSS version 19.0 (IBM, USA). Means are presented as mean ± standard deviation (SD), Student’s t-test was used to analyze the normally distributed numerical variable; Pearson chi-squared test or Fisher’s exact test was used to analyze the qualitative variable. The significance level used for all tests was p < 0 0.05.