gms | German Medical Science

Objectives: The effect of positive cultures on subsequent failure in two-stage exchange arthroplasty is not known. The aim of the current study was to identify the incidence of positive culture during reimplantation and to analyze its' correlation with the outcome.

Methods: In this single-center prospective cohort study all hip and knee PJI cases from 2013 to 2015, which were treated by a standardized comprehensive diagnostic and therapeutic algorithm with two-stage exchange, were included. Treatment failure was assessed according to the Delphi-based consensus definition. Logistic regression analysis was performed to assess the predictors of positive culture and risk factors for failure.

Results and Conclusion: We analyzed 182 two-stage revision arthroplasties (93 hips, 89 knees). In 30 (16.5%) cases more than 1 positive culture could be detected during reimplantation. Of these 30 cases, 8 (26.7%) had a subsequent failure compared with 19 (12.5%) of the cases that were culture-negative at reimplantation (p=0.09). Same microorganism was isolated during reimplantation as the initial infecting organism only in 11 of 30 cases (36.7%). The microorganism causing reinfection was in none of the cases the same as isolated at reimplantation. The risk of treatment failure was significantly higher in cases with a higher Charlson comorbidity index (odds ratio [OR]= 1.3; 95% confidence interval [CI]= 1.04 to 1.6; p=0.02). Furthermore, difficult-to-treat microorganisms at explantation were only independent risk factor for developing a positive culture at reimplantation (OR= 1.75; 95% CI= 1.4 to 2.7; p=0.01). Positive culture at reimplantation showed a noticeable trend of subsequent failure. Treating physicians should be aware of the association between positive culture at reimplantation and subsequent failure and consider a medical optimization of patients with severe comorbidities prior and parallel to therapy.