In 2017, the French Society in anesthesia and reanimation published new recommendations on intraoperative antibiotic prophylaxis. Now, no more than 48 hours of antibiotic prophylaxis applies to any otolaryngology surgery, regardless of patient's medical history or type of flap used to rebuild. This has resulted in an alignment of our local protocol in Croix-Rousse hospital.

However, after few years, our local impressions are that bone flap surgeries are very likely to provide surgical site infections (osteo-articular or non-osteo-articular infections).

The prejudice of these postoperative site infections is significant, with serious consequences,. of both functional and aesthetic sides.

We wanted to objectify this impression by retrospectively analyzing the data relating to patients operated on for bone flapsurgeries.

Knowing the operation site infection rate after surgery for otolaryngology bone flap surgery will allow us to objectively understand the infectious risk of these surgeries, in particular the risk of osteoarticular infection. Identifying operation site infection factors will allow us to better target and prevent them.

The goal is to find out if the antibiotic prophylaxis currently recommended is sufficient and effective for this type of surgery.

Inclusion Criteria:

• Patient operated for bone flap in Croix-Rousse hospital, in otorhinolaryngology department, since september 2012 and until January 2019

Exclusion Criteria:

• patient's opposition to participate in the study

Patient operated on for bone flap surgery by the Otorhinolaryngology surgery team in Croix-Rousse hospital (Pr CERUSE)