Two-stage reimplantation for periprosthetic knee infection: Influence of host health status and infecting microorganism.

BACKGROUND: Two-stage revision is the gold standard treatment of TKA infection; nevertheless various factors may influence the success rate. The aim of our study was to assess the impact of the number of patient comorbidities together with virulence of infectious organism on prognosis of two-stage revision procedure in chronic peri-prosthetic knee infection; moreover we tried to demonstrate correlation between the presence of positive culture during re-implantation and re-infection rate.

METHODS: Thirty-eight cases of two-staged revision procedures for infected total knee arthroplasty were prospectively followed. The presence of high virulence microorganisms on the culture result and the number (more than three) of comorbidities were used as major risk factors. All cases were divided into three groups: Group 1 (10 patients without major risk factors), Group 2 (18 patients with only one major risk factor), Group 3 (10 patients with both of major risk factors).

RESULTS: After a mean follow-up of 65months (range 24-139months), there was infection recurrence in nine cases: four re-infections occurred with the same organism while five patients had re-infection with a different organism. Recurrence was higher in Group 3 (33% of the cases), lower in Group 2 (12% of the cases), whereas no infection occurred in Group 1. Finally in case of positive intraoperative cultures recurrence rate was 83%, whereas when specimens were negative we had only 12.5% of re-infections.

CONCLUSIONS: Even if standard protocol of two-stage revision has demonstrated good results when treating low-virulence infections or patients without associated risk factors, its application to more challenging condition cannot be assumed.

LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of level of evidence.