This study received from Bioethical Committee at the Centre of Postgraduate Medical Education in Warsaw approval number 13/PB/2016 on 9 March 2016 and was successfully retrospectively registered at ClinicalTrial.gov with identification number: NCT04486040 (registration date 24/07/2020). All methodology was performed according to above institution guidelines.
A total number of 40 consecutive patients who underwent RHA and signed their informed consent for participation were included in this prospective study and achieved final follow-up. All patients were treated in Orthopedic Department, Centre of Postgraduate Medical Education in Otwock. The inclusion criteria were set as RHA performed due to aseptic implant loosening (cup, stem or both elements). Septic implant loosening, primary or secondary coagulopathy, chronic inflammatory diseases (such as rheumatoid arthritis, ankylosing spondylitis), concomitant malignancy, renal or hepatic failure, as well as thromboembolism in the past were stated as exclusion criteria.
Simple randomization with an allocation ratio of 1:1 was performed. Envelopes with information on drainage use (or not) were drawn and opened at the end of surgery by the anaesthesiologist team. Up to this moment neither the patient or orthopaedic surgeons knows what type of intervention will be applied. Unblided reasercher collected postoperative data. Patients were typically prepared for revision surgery. According to the authors' national recommendations, every patient got thromboprophylaxis with the use of ultra-low molecular weight heparin (ULMWH) before surgery and this was continued for 35 days. All patients received antibiotic prophylaxis and tranexamic acid was administered (one dose 15 minutes before the surgery and a second dose 6 hours after). In all cases between 3 to 6 samples (synovial fluid, periprosthetic tissues and implant for sonication) were taken for microbiological culturing. All patients got empiric antibiotic therapy until receipt of results of intraoperative microbiological specimens. However, no prior infection was confirmed. If drainage was used, it was removed after 24 hours. All patients were walking with two crutches on the first day after surgery. On the third day after the operation, all patients underwent ultrasonography (USG) for the measurement of the fluid in the joint and the presence of haematoma in soft tissue. For the USG all patients were lined up in the same position [15]. If soft tissue haematoma was confirmed, depending on indications, punction and evacuation was performed. C-reactive protein levels (CRP), haemoglobin, haematocrit were measured in the early postoperative period on the first and third day, and at the first control outpatient visit after 6 weeks. All data were collected by the primary investigator and all USG exams were performed by one examiner. We assessed wound healing as dry or excluded dressing after 3 days post-surgery.
Primary outcomes were blood loss after surgery, joint haematoma, haemoglobin level after surgery, and infection. To assess “hidden” blood loss the Gross formula was used [16]. Signs of infection like wound healing problems, fever, hip pain, CRP increase, were noted directly after surgery and at all check visits. Secondary outcomes were set as soft tissue haematomas, C-reactive protein levels, need for blood transfusion after revision hip replacement. Patients’ clinical and functional outcomes were measured with Harris Hip Score (HHS) before surgery and 6 weeks after and Visual Analogue Scale (VAS) before surgery and on 3rd day after surgery (range 1–10).
Intention-to-treat analysis were performed. Analyses were performed using Statistica 13.1 for Windows (StatSoft, Inc., STATISTICA for Windows, Tulsa, OK). Variables were reported as mean, standard deviation, range (min/max). The analysed groups were compared using descriptive statistics, cross-tabulation tables, and non-parametric statistics analysis. For comparison between groups the T-Test for Independent Samples for normally distributed data was used. The Mann-Whitney U test for non-normally distributed data was used. Categorical data were compared by means of the Chi-squared test, M-L Chi-square test and Yates Chi-square test. Tests results were defined as statistically significant with p < 0.05 (p values < 0.05 were considered statistically significant).
After including 20 patients in each group the research was unblinded and preliminary statistical analysis was done. We revealed significant differences in terms of total and percentage blood loss, and Hgb drop on the first postoperative day as primary investigated outcomes. Thus, the decision to stop the trial and further randomization to reduce the risk to patients was made.