The proper timing of second-stage revision in treating periprosthetic knee infection: reliable indicators and risk factors

BACKGROUND: Two-stage revision is the standard procedure for periprosthetic knee infection. But when to perform the second-stage is still under debate. We attempt to search the reliable indicators, risk factors, and proper timing for the second-stage revision. METHODS: We reviewed and followed 81 infected total knee arthroplasty patients who underwent two-stage revision from January 2010 to January 2014. Our cohort included 56 males and 25 females, all patients were confirmed as PJI with the same phenotypic cultures. The average age was 64.8 ± 8.21 (range 36–78) months. The mean follow-up time was 46.5 ± 17.6 (range 12–72) months after the second-stage surgeries. The diagnostic parameters including serum C-reaction protein, erythrocyte sedimentation rate, and intraoperative frozen section at the time of re-implantation were analyzed. The spacer detention time and antibiotic treatment time were compared. RESULTS: Ten of them went through failed first- or second-stage surgeries. The overall success rate was 87.7%. The intraoperative frozen section is a good indicator at the time of re-implantation; the sensitivity and specificity is 90 and 83.1%. Serum CRP and ESR showed poor diagnostic value at time of re-implantation. Atypical pathogen infection, positive FS, and previous sinus were high-risk factors for failure of two-stage revision. Spacer detention time between 12 and 16 weeks had higher success rate than over 16 weeks. CONCLUSION: The proper timing of re-implantation should be combined with disappearance of clinical symptoms and negative intraoperative FS with spacer detention time at 12 to 16 weeks.