Peri-implant infections are severe complications after internal fracture fixation surgery. Detection of causative agents of orthopedic implant-associated infections (OIAI) is demanding. Several authors reported increased identification rates of bacterial prevalence using different sonication procedures compared to standard tissue cultures samples, especially for low grade infections.

On the author hand, contamination of implants without clinical signs of infection is reported in up to 30% during implant removals after uneventful fracture healing. The raised general questions are: 1.) Is a positive microbiological finding the result of contamination during the index surgery or during implant removal? 2.) Does contaminated implants without clinical or serological signs of infection have a pathological value?

In this prospective case study, the detection rates of different diagnostic tools for peri-implant contaminations during removal of syndesmotic screws should be compared and the clinical consequence of positive findings evaluated in follow up investigations up to 6 months.

Patients with ankle fractures (Weber B and C) treated operatively in our department by open reduction and internal fixation with plates and additional syndesmotic screw should be included. After patients´ informed consent, several microbiological samples should be taken for further microbiological analysis during the standard syndesmotic screw removal 6-8 weeks after the index surgery. At follow up of two weeks after screw removal a clinical examination and serological analysis for infection will be performed. The endpoint of study is fracture healing at six months.

Inclusion Criteria:

• Patients with syndesmotic screw removal after open reduction and internal fixation with plates and additional syndesmotic screw of ankle fractures (Weber B or C) in our department.

Exclusion Criteria:

• Patients with immunosuppressive diseases or therapies,
• Pregnant women
• Patients with pre-operations on the same ankle-joint
• Patients with initial surgery for fracture fixation in other hospitals.

Patients with operatively treated ankle fractures.