TKA後感染に対する治療戦略

―人工関節を温存するためには―

抄録

Objective: Debridement, antibiotics, and implant retention (DAIR) is performed for periprosthetic joint infection (PJI) after total knee arthroplasty (TKA). The aim of this study was to identify prognostic factors associated with successful DAIR in patients with PJI.

Patients and methods: The study included 52 knees in 51 patients who were treated according to the same protocol for infected TKA. The outcome of treatment and the success rate of DAIR were assessed in these cases. Patient characteristics, timing of infection onset, time from onset of infection to start of treatment, and type of causative bacteria were compared between the implant retention group and the implant removal group, and factors associated with successful implant retention were investigated.

Results: The implant was ultimately retained in 17 of 52 (32.7%) knees, and the success rate for implant retention using DAIR was 45.9% (17/37 knees). The success rate for implant retention by the onset timing of infection was 50% in early postoperative infections, 61.5% in acute hematogenous infections, and 13.8% in late chronic infections, showing a low success rate for retention in cases of late chronic infection. The success rate for implant retention by time from onset of infection to start of treatment was 65.4% in those who started treatment ≤2 weeks and 0% in those who started ≥2 weeks (significantly different), suggesting the importance of early treatment. Calculation of a cutoff value using ROC curve demonstrated that performing DAIR between the onset of infection to day 13 results in a high probability of retaining the implant. Regarding the causative bacteria, methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis led to poor outcomes with low success of retaining the implant.

Conclusion: To retain the implant in PJI after TKA, DAIR should be performed within 13 days of onset of infection, with consideration for the type of causative bacteria, in those with acute infections such as early postoperative infections and acute hematogenous infections.