Studies on sonication suffer from a heterogeneity which makes their analysis complex, due to the absence of a gold standard allowing positive cases to be defined unequivocally. Thus, the sensitivity of the technique has been assessed on cases defined in different ways, which makes the studies difficult to compare (number of samples taken, number of positive samples, variable duration of culture, etc.). It should nevertheless be noted that the majority of the series conclude with a higher sensitivity than that of standard samples, in particular in the event of a strain with difficult growth (Cutibacterium acnes, deficient Streptococci) or in the event of prior antibiotic therapy.

In the absence of a comparative reference allowing to conclude on the intrinsic performances of sonication as a diagnostic test, it seems interesting to evaluate its contribution in current practice, in particular in the difficult cases where the standard culture does not make it possible to fulfill the criterion. major (zero or only one positive sample). To the knowledge of the investigators, there is no study of this kind, which could make it possible to specify the place of this technique in the diagnostic procedure and to improve the care of patients.

Inclusion criteria:

• Adult patients (age ≥18 years)
• Have been hospitalized and operated on for a change of hip or knee joint prosthesis between 01/01/2019 and 07/31/2022
• Have had at least 3 samples taken for microbiological purposes, pre- or intraoperatively
• the explanted prosthesis must have been analyzed by sonication.
• not opposing the reuse of its data for scientific research purposes

Exclusion criteria:

- Opposition of the patient to the reuse of his data.

Adult patients (age ≥18 years) have been hospitalized and operated on for a change of hip or knee joint prosthesis between 01/01/2019 and 07/31/2022