The study was planned and conducted using a prospective randomised design. We performed simple randomisation using closed envelopes designating group allocation. The study was successfully retrospectively registered in Clinicaltrial.gov with identification number: NCT04333264 (03/04/2020).
The study began on 9 March 2016, after obtaining approval from our Bioethical Review Board. All methods provided in these study was carried out in accordance to approval from Bioethical Committee of Centre of Postgraduate Medical Education in Warsaw with approval number 13/PB/2016. Patients successively admitted to the ward for hip replacement were eligible for inclusion. All patients signed informed consent. Patients were prepared for surgery in a typical manner. LMWH was used for thromboprophylaxis in doses adjusted for body weight and risk factors. The first heparin dose was administered in the evening of the day before surgery. Thromboprophylaxis was continued for 35 days after surgery. All patients received tranexamic acid (Exacyl) intravenously, at a dose of 15 mg per kilogram of body weight, 10 minutes before skin incision. Experienced surgeons performed surgeries through a posterolateral approach with cementless hip replacement implantation. In all patients, wound healing was monitored during the postoperative period.
Over the 72 hours after surgery, all patients underwent ultrasound scans of their hip joints and the post-surgical wound using the aseptic technique. The scans were performed with patients in the supine position. The ultrasound scan assessed the fluid level at the level of the endoprosthesis neck and detected fluid accumulation in the soft tissues.
Blood loss volume, along with the occult bleeding, was analysed using the Gross formula:
EBV represented the estimated patient’s blood volume, Ht(0) represented haematocrit before surgery, Ht(1) represented haematocrit 24 hours after surgery, and Htav represented estimated pre- and postoperative haematocrit value. Despite limitations such as intraoperative fluid transfusion or renal insufficiency, the Gross formula is thought to estimate interoperative blood loss credibly .
Before surgery and within 72 hours afterwards, the range of hip joint motion was assessed for flexion, abduction, adduction, and flexion contracture. Pain levels were assessed using the visual analogue scale (VAS) in all patients. Physical examination and ultrasound scans were conducted 72 hours after surgery by the same physician. Patients were discharged depending on their general condition and progress in rehabilitation, usually from the third to seventh day after surgery. The follow-up period was 30 days.
A total of 134 patients were successively operated on from 14 March 2016 to 16 May 2018, meeting the study inclusion and exclusion criteria.
The inclusion criteria were primary hip osteoarthritis and age between 30 and 80 years. The exclusion criteria were secondary degenerative hip joint disease, autoimmune disease, congenital/secondary coagulopathy, history of venous/arterial thrombosis, hepatic/renal insufficiency, cement or hybrid endoprosthesis, and lack of patient consent.
Patients were allocated to two groups depending on the presence or absence of drains; 100 patients qualified for the final analysis, of which 20 patients later withdrew consent for participation in the study. In eight patients, the surgeon decided to use suction drainage, regardless of randomisation results; and in six, a cemented implant was used because of intraoperative conditions.
The allocation process was performed with simple randomisation use. Closed envelopes, with information on drainage usage, was opened in the operating theatre at the end of surgery. If the surgeon, considering the procedure and local conditions, decided that suction drainage was necessary, the patient was excluded from the study.
The investigated group included 55 females (55%) and 45 males (45%). The mean age was 62.8 years (range, 30–82 years)—64 years for women (range, 34–76 years) and 61.4 years for men (range, 30–82 years). The mean body mass index (BMI) was 28.95 kg.m2 (men: 29.28 kg.m2; women: 28.68). All patients were assessed for the severity of hip osteoarthritis using the Kellgren–Lawrence scale (Figure. 1).
Calculations were made using Statistical Analysis System (version 9.4) software. Quantitative data were examined using the Student’s t-test, and distribution was assessed using the Shapiro-Wilk test. To examine qualitative characteristics, contingency analysis was used; for these analyses, X2 with Yates’s correction and Fisher’s F-tests were applied.