Methods: A retrospective cohort of TKA PJI treated with two-stage exchange was identified by query of hospital coding records from 2009 to 2014, with subsequent chart review. The primary endpoint was defined as prosthesis retention for 2 years from reimplantation. Microbiologic relapse was defined as a recurrence of a previously treated organism. Descriptive statistics were completed using the Fisher’s exact test for categorical variables and the Mann-Whitney U test for continuous variables.
Results: 159 patients who underwent 2-stage exchange for a TKA PJI meeting Musculoskeletal Infection Society International Consensus criteria were identified. The average age was 66 years, and 37% were female. 141 underwent reimplantation; 24 of these (17%) had recurrent infection. Of the 24 patients who developed infection after reimplantation, only 4 relapsed with the same microbe; the other 20 (83%) were diagnosed with new, microbiologically distinct organisms. 3 of these 4 recurrences were due to Staphylococcus aureus infection. The likelihood of microbiologic relapse was low among reimplanted patients (3%). In univariate analysis, no associations were found between outcome and age, comorbidities, or BMI.
Conclusion: Two-stage exchange arthroplasty for TKA infection is associated with a very low rate of microbiologic relapse. However, those patients able to undergo reimplantation remain at risk of subsequent infections with new microbes. It remains important to continue to modify risk factors in patients who have undergone a two-stage exchange for PJI.
A. Nocon, None
G. Westrich, None
B. Brause, None
A. Miller, None