**Evaluation of a New Strategy for Protocolized Antibiotic Care for Severe Open Fractures: SEXTANT** This study compares two treatments for severe open fractures, which are serious bone breaks with open wounds. We are testing a new way to give antibiotics, called the SEXTANT protocol, to see if it works better than the usual treatment. Antibiotics are medicines that fight infections. The study will involve people with specific types of leg and ankle fractures. We will look at how often infections happen with each treatment and check if the new method causes fewer bad side effects. We will also try a new, fast way to find germs in the wounds. **Key Points:** - **Length & Visits**: The study involves multiple visits as it observes the healing process and any infections over time. - **Eligibility**: Participants must be aged 18-64 with specific types of severe fractures. - **Risks**: There may be risks related to antibiotics and wound infections, which will be monitored closely. If you join the study, your treatment will be managed carefully, and you'll help us learn how to better care for people with severe fractures.