A hip or knee prosthesis can be cemented or not. The team of orthopedic surgeons from the CCOM (Centre de Chirurgie Orthopédique et de la Main) has been cementing all hip and knee prosthesis poses for many years using gentamycin cement as recommended by the French Society of Orthopedic Surgery. and trauma (SOFCOT) (1). Data obtained from the Norwegian Register of Hip Prostheses show that the best survival curve for these prostheses is found for prostheses cemented with gentamycin cement (all causes combined). Independently of the risk of aseptic loosening, infection on the prosthesis is the second complication of arthroplasty. The defense mechanism against pathogens in contact with an implant is the formation of a biofilm. Biofilm bacteria are metabolically inactive and characterized by stationary growth. Due to their slower replication, bacteria in biofilm are up to 1000 times more resistant to antibiotics. Therefore, the optimization of local antibiotic prophylaxis is essential.

Inclusion criteria:

• Adult subject (≥18 years old)
• Patient operated on at the HUS between 01/02/2017 and 31/01/2019, for replacement of hip and knee prostheses
• Patient having given their consent for the reuse of their data for the purposes of this research

Exclusion criteria:

- Patient who expressed their opposition to participating in the study

Adult subject (≥18 years old) operated on at the HUS between 01/02/2017 and 31/01/2019, for replacement of hip and knee prostheses.