Abstract
Introduction
There is no literature regarding the risk of a patient developing PJI after primary TKA if the patient has previously experienced PJI of a TKA or THA in another joint. The goal of this study was to compare the risk of PJI of primary TKA in this patient population compared to matched controls.
Methods
We retrospectively reviewed 95 patients (102 primary TKAs) from 2000–2014 with a history of a TKA or THA PJI in another joint. Mean age was 69 years; mean BMI was 36 kg/m2. 27% high-risk patients were on chronic antibiotic suppression. Mean follow-up was 6 years. We 1:3 matched (to age, sex, BMI, and surgical year) these to 306 primary TKAs performed in patients with a THA or TKA of another joint without a subsequent PJI. Competing risk with death was used for statistical analysis. Multivariate analysis was utilized to evaluate risk factors for PJI in the study cohort.
Results
The cumulative incidence of PJI in the study cohort (6.1%) was significantly higher than the matched cohort (2.6%) at 10 years (HR=3.3, p=0.02). Host grade in the study group was not a significant risk factor for PJI. Patients on chronic suppression had a higher rate of PJI (HR=15, p=0.002), with 6 of 7 patients developing a PJI being on chronic suppression. The new infecting microorganism was the same as the previous in only 2 of 7 patients.
Conclusion
In this matched cohort study, patients undergoing a clean primary TKA with a history of a TKA or THA PJI in another joint had a 3-fold higher risk of PJI compared to matched controls with a 10-year cumulative incidence of 6.1%. The risk of PJI was 15-fold higher in patients on chronic suppression; further investigation into reasons for this and mitigation strategies is recommended.
