Between 2009 and January 2016, the investigators included 49 patients from four hospitals in Lyon who had a Total Knee Arthroplasty (TKA) infection and who benefited of a knee arthroplasty revision with a rotating hinge prosthesis. This retrospective and descriptive cohort aims at studying the functional results after 2 years follow up.

Inclusion Criteria:

- All the patients who had a rotating hinge knee arthroplasty for septic revision after total knee arthroplasty, proved by bacteriological samples or purulent drainage at involved site or other obvious clinical signs or radiological signs of infection

Exclusion Criteria:

- Patients who benefited of a hinge prosthesis following a unicompartmental prosthesis, following a mechanical issue on a total prosthesis

Patients having a hinge knee prosthesis following an infection on a total knee prosthesis .

Pre-operative characteristics studied :

Clinical characteristics : medical and surgical history on the index knee included the strategy of the infection treatment (one step treatment vs two steps treatment)and general contributing factors of infection, frontal laxity, join motions, initial constraint of the infected TKA, skin condition ( skin necrosis, fistula, flap need, scar condition) paraclinical characteristics : bone defects, condition of knee extensor system ( continuance, height of patella, joint space height (when possible to measure)), prosthethic sealing or unsealing on CT-scan or scintigraphy, causal germ(s)