Aims

Cementless primary total hip arthroplasty (THA) is associated with risks of bleeding and thromboembolism. Anticoagulants are effective as venous thromboprophylaxis, but with an increased risk of bleeding. Tranexamic acid (TXA) is an efficient antifibrinolytic agent, but the mode and timing of its administration remain controversial. This study aimed to determine whether two intravenous (IV) TXA regimens (a three-hour two-dose (short-TXA) and 11-hour four-dose (long-TXA)) were more effective than placebo in reducing perioperative real blood loss (RBL, between baseline and day 3 postoperatively) in patients undergoing THA who receive rivaroxaban as thromboprophylaxis. The secondary aim was to assess the non-inferiority of the reduction of blood loss of the short protocol versus the long protocol.

Aims

An evidence-based radiographic Decision Aid for meniscal-bearing unicompartmental knee arthroplasty (UKA) has been developed and this study investigates its performance at an independent centre.

Purpose of the study: The efficacy of a new oestrogeneration biomaterial should be demonstrated by in vivo grafts in animal models. Critical filling of bone defects in the rat could be useful as a model before beginning studies in large animals such as the sheep, goat or dog. Creation of a critical defect in the rat femur has been described, but not standardized, leading to difficult comparison between series. In this work, we wanted to establish a detailed standardisable surgical protocol for the creation of a 6 mm femur defect in the rat.

Material and methods: We compared three anaesthesia protocols using 18 mal Wistar rats aged 21 weeks. We developed a surgical procedure enabling study of the advantages of the different commonly used surgical devices either in research or clinic to achieve osteosynthesis and a 6 mm bone defect. We also compared two types of fixation plates (and screws) available on the marker: a 1.2 mm thick titanium plate used for hand surgery and a 1.5 mm steel plate (veterinary medicine). Our postoperative clinical and radiographic follow-up was designed to validate our operative protocol and evaluate osteoregeneration.

Results: We demonstrated first that the use of multimodal anaesthesia radically improved the clinical outcome in the animals. We then demonstrated that the 1.2 mm titanium plates recommended in other studies were too fragile in our model and that the steel 1.5 mm veterinary plates were more adapted. We finally demonstrated the superiority of surgical devises to create a defect and for osteosynthesis. We described a postoperative protocol offering satisfactory evaluation, clinically and radiographically.

Discussion: This work is the first describing this protocol in detail. Improvements in feasibility and cost will make a readily exploitable model for other laboratories. The follow-up on this work should be aimed at improving the quality and pertinence of the analysis methods for the assessment of bone regeneration.

Conclusion: We propose a mode for the critical defect in rat femur bone as a reliable model for the study of osteogenic capacities of new biomaterials.