Postoperative surgical site infection in patients treated with lumbosacral fusion has been believed to be caused by perioperative contamination (Perioperative Inside-Out infections) in patients with comorbidities. With the proximity of these incisions to the perianal region and limited patient mobility in the early post-operative period, local contamination from gastrointestinal and/or urogenital flora (Postoperative Outside-In infections) should be considered as a major source of complication.

A single center, retrospective review of adult patients treated with open posterior lumbosacral fusions between January 2014 and January 2021. We aimed to identify common factors in patients experiencing deep postoperative infections. Oncological, minimally invasive, primary infection, and index procedures carried out at other institutions were excluded.

We identified 489 eligible patients, 20 of which required debridement deep to the fascia (4.1%). Mean age (62.9 vs 60.8), operative time (420 vs 390 minutes), estimated blood loss (1772 vs 1790 mL) and median levels fused (8.5 vs 9) were similar between the infected and non-infected groups. There was a higher percentage of deformity patients (75% vs 29%) and increased BMI (32.7 vs 28.4) in the infected group. The mean time from primary procedure to debridement was 40.8 days. Four patients showed no growth on culture. Three showed Staphylococcus species (Perioperative Inside-Out infections) requiring debridement at a mean of 100.3 days (95%CI 0- 225 days). Thirteen patients showed infection with intestinal or urogenital pathogens (Postoperative Outside-In infections) requiring debridement at a mean of 20.0 days (95%CI 9-31 days). Postoperative Outside-In infections led to debridement 80.3 days earlier than Perioperative Inside-Out infections (p= 0.007).

In this series, 65% of deep infections were due to early local contamination by gastrointestinal and/or urogenital tracts pathogens. These infections were debrided significantly earlier than the Staphylococcus species infections. Due to the proximity of the incisions to the perianal region, there should be increased focus on post-operative local wound management to ensure these pathogens are away from the wound during the critical stages of wound healing.

Introduction: Venous thromboembolism (VTE) after major orthopaedic surgery remains an important clinical problem. Convenient, oral antithrombotic agents that are both safe and effective could improve adherence to guidelines for VTE prevention. Recently, the focus has been on the development of oral agents that target a single step in the coagulation cascade. Factor Xa is the pivotal point in the coagulation cascade, making it a particularly attractive target for anticoagulant drugs. Rivaroxaban is an oral, direct Factor Xa inhibitor. Four international phase III trials (the RECORD programme) are being undertaken to investigate the safety and efficacy of once-daily rivaroxaban for thromboprophylaxis after major orthopaedic surgery. The results of RECORD3 showed that rivaroxaban was more effective than enoxaparin 40 mg once daily after total knee replacement (TKR), with a 48% risk reduction in VTE and all cause mortality. RECORD4 is designed to compare rivaroxaban 10mg once daily with enoxaparin 30 mg every 12 hours for thromboprophylaxis following TKR.

Methods: RECORD4 is a prospective, double-blind trial in which approximately 3000 TKR patients worldwide are being studied. Patients are randomized to receive either oral rivaroxaban 10 mg (starting 6–8 hours after surgery and continued once daily), or subcutaneous enoxaparin 30 mg (given every 12 hours and starting 12–24 hours after surgery). Study medication is given for 10–14 days, and mandatory bilateral venography is undertaken the following day. The primary efficacy outcome is a composite of deep vein thrombosis (DVT; symptomatic, or detected by mandatory venography), non-fatal pulmonary embolism (PE), and all-cause mortality. The major secondary efficacy outcome is major VTE (the composite of proximal DVT, PE and VTE-related death). The primary safety outcome is major bleeding. Other safety endpoints include all bleeding events, cardiovascular events and abnormal laboratory parameters.

Results: The final results of this trial will be presented.

Conclusions: The results of this trial will provide valuable data concerning the use of rivaroxaban for thromboprophylaxis after TKR in the North American setting.