This study is a prospective bicentric feasibility study, which aims to evaluate the feasibility of a two-stage full implant exchange with early prosthesis reimplantation between 16 and 30 days after implants removal for hip or knee prosthetic joint infection.

This study concern 50 patients, prospectively included and compared to the last 50 patients with hip or knee PJI managed with classical two-stage implant exchange.

The duration of the study is 42 months.

Prosthetic joint infection (PJI) is a rare but severe complication, with long and complex medico-surgical procedures ang high morbidity. Two-stage full implant exchange is commonly used for PJI, but the best time for prosthesis reimplantation remains unclear. Late reimplantation leads to prolonged immobilization, which can cause decubitus complications and altered joint functionnality.

The hypothesis is that reimplantation between 16 and 30 days after implants removal, earlier than suggested by some relatively old recommandations, associated with 12 weeks antibiotic therapy is a safe and efficient option, allowing shorter immobilization susceptible to improve joint functionnality.

The principal aim of this study is to evaluate the feasibility of a two-stage full implant exchange with early prosthesis reimplantation.

50 patients with knee or hip PJI eligible for two-stage implant exchange will be prospectively included in two french centers.

Surgical procedure will be standardized, with prothesis reimplantation within 16 to 30 days after implants removal, associated with 12 weeks adaptated antibiotherapy according to french recommendations.

Patients will be compared to the last 50 patients with hip or knee PJI managed with classical two-stage implant exchange in these centers until december 2021 (retrospective group).

Follow up consists of 7 clinical evaluations, from inclusion until month15 after prosthesis removal.

Inclusion Criteria:

Prospective group:

• Patient over 18 years old
• Patient managed for a definite osteoarticular infection in a hip or knee prosthesis according to EBJIS definitions (2021) Clinical definition : fistula communicating with the prosthesis, prosthesis exposed / Or biological ≥ 2 samples positive for the same microorganism / And/ or 3000 leukocytes or > 80% of PNN on the synovial fluid / Or histological: visible microorganism, > or = 5 PNN on 5 HPN
• Patient with an indication for 2-stage surgery:

A Impossibility of conservative treatment : infection occurring more than 4 weeks after prosthesis implantation, fistula, documented resistant germ, loosened prosthesis / B Unsuitable 1-stage change: recurrence after 1-stage management, precarious bone capital, documented resistant microorganism, infection without prior microbiological documentation, fistula, surgeon's assessment in disfavor

- Effective contraception during the research period for fertile women of childbearing age

Retrospective group :

• Patient managed before 31/12/2021 for a definite osteoarticular infection in a hip or knee prosthesis according to EBJIS definitions (2021) Clinical definition : fistula communicating with the prosthesis, prosthesis exposed Or biological ≥ 2 samples positive for the same microorganism And/ or 3000 leukocytes or > 80% of PNN on the synovial fluid Or histological: visible microorganism, > or = 5 PNN on 5 HPN
• Patient managed by 2 "long" stage surgery with reimplantation time > 6 weeks with an evolutionary follow-up of at least 15 months after the end of antibiotics

Exclusion Criteria:

Prospective group :

• Indication for conservative treatment, 1-stage or 2 long stage surgery
• Reimplantation by another surgical approach requiring complete skin closure of the initial scar
• Other surgeries scheduled within 30 days of removal
• Participation in another interventional treatment study and/or in an exclusion period due to participation in another protocol
• Subject not affiliated with a social security plan or beneficiary of such a plan
• Failure to obtain written informed consent
• Patient with a legal protection measure (guardianship, curatorship)
• Patient under justice safeguard
• Pregnant or breastfeeding woman

Retrospective group :

- Refusal to participate

Study exit criteria

• Bacteriological samples positive for fungi
• Infection not retained after analysis of samples (no sufficient clinical or biological criteria according to EBJIS definition)
• Withdrawal of consent