This retrospective study is to analyse microbiological cultures from the sonication fluid of the explanted prothesis to detect bacteria in the biofilm on the implant surface and to investigate whether the number of bacteria in the biofilm correlates with the duration of the PJI respectively with the period between symptom onset and date of revision surgery.

Implant associated infections in orthopaedics and trauma surgery are a well-known and feared complication. Prosthetic-joint infection (PJI) is caused by a biofilm which is located atop the surface of the implant which as growing with the duration of the PJI. This retrospective study is to analyse microbiological cultures from the sonication fluid of the explanted prothesis to detect bacteria in the biofilm on the implant surface and to investigate whether the number of bacteria in the biofilm correlates with the duration of the PJI respectively with the period between symptom onset and date of revision surgery.

Inclusion Criteria:

• patients who underwent a revision surgery of hip, knee and shoulder arthroplasties operated at the university hospital of Basel between 2011 and 2021,
• patients who had a PJI as a suspected diagnosis and
• have microbiological cultures from sonication fluid from removed prosthesis.

Exclusion Criteria:

• patients in the database who

  1. have non-bacterial microbiological positive cultures (e.g. fungal infection) and
  2. have not received a sonication of the removed prosthesis during the diagnostic process

Patients who meet the required criteria will be extracted from an existing clinical consultation database of the clinic of infectious disease. All patients in this database were treated and recorded on a consultative base between 2011 and 2021 by the Department of Orthopaedics and Traumatology and the Department of Infectious Diseases at the University Hospital Basel for a suspected PJI.