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Published on: December 3, 2017
Isolation of Multiple Positive Cultures at Resection Arthroplasty is a Predictor of Failure Following Reimplantation
Saad Tarabichi1, David G Deckey1, Jens T Verhey1
1Department of Orthopaedic Surgery, Mayo Clinic Arizona, Phoenix, Arizona.
Background:
Although it is well established that the type of organism can be a risk factor for failure in patients with periprosthetic joint infection (PJI), no study to date has examined the impact of the number of positive cultures on treatment outcomes in patients undergoing 2-stage exchange. The purpose of this multicenter study was to determine the prognostic utility of multiple positive cultures at resection as a predictor of failure following reimplantation.
Methods:
This retrospective multicenter study identified 437 patients with chronic knee PJI who had undergone 2-stage exchange arthroplasty with a minimum of 1 year of follow-up following reimplantation. PJI was defined with use of the 2013 Musculoskeletal Infection Society (MSIS) criteria. Patients with culture-negative PJI were excluded (n = 138). Treatment failure was defined as either any reoperation for infection or PJI-related mortality. Multivariable regression controlling for risk factors for failure after a 2-stage arthroplasty was performed to determine whether ≥2 positive intraoperative cultures at resection can predict outcomes following reimplantation when compared with a single positive culture.
Results:
Two hundred and ninety-nine patients were included. At a mean follow-up of 6.2 ± 2.6 years, 48 patients (16.1%) experienced failure. Patients who had a failure were more likely to have had a longer interstage interval (p = 0.038) and were also more likely to have had ≥2 positive cultures at the time of resection arthroplasty (95.8% versus 75.3%; p = 0.001). On regression analysis, ≥2 positive cultures at resection was the only variable that was identified as a risk factor for failure following reimplantation in both the univariate (odds ratio [OR], 7.55 [95% CI, 2.24 to 47.0]; p = 0.006) and multivariable models (OR, 8.12 [95% CI, 2.31 to 51.9]; p = 0.005).
Conclusions:
This is the first study to examine the impact of the number of positive cultures on outcomes in patients with PJI. We found that the presence of ≥2 positive cultures at resection was an indicator of a poor prognosis and resulted in a greater than eightfold increase in the risk of treatment failure in patients undergoing a 2-stage exchange.
Level Of Evidence:
Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.
Insights
Multiple positive cultures during periprosthetic joint infection (PJI) treatment indicate a higher risk of failure. This finding is crucial for predicting outcomes in patients undergoing 2-stage exchange surgery for PJI.
Area of Science:
- Orthopedic Surgery
- Infectious Diseases
- Biostatistics
Background:
- Organism type is a known risk factor for periprosthetic joint infection (PJI) treatment failure.
- The impact of the number of positive cultures on 2-stage exchange outcomes in PJI remains unexamined.
- This study investigates the prognostic value of multiple positive cultures at resection.
Purpose of the Study:
- To determine if multiple positive intraoperative cultures at resection predict treatment failure in patients undergoing 2-stage exchange for chronic knee PJI.
- To compare the outcomes of patients with ≥2 positive cultures versus a single positive culture.
Main Methods:
- Retrospective multicenter study of 299 patients with culture-positive chronic knee PJI undergoing 2-stage exchange.
- Exclusion of culture-negative PJI cases (n=138).
- Multivariable regression analysis controlling for known risk factors, comparing outcomes for ≥2 positive cultures versus a single positive culture.
Main Results:
- At a mean follow-up of 6.2 years, 16.1% of patients experienced treatment failure (reoperation or PJI-related mortality).
- Patients with treatment failure were more likely to have had ≥2 positive cultures at resection (95.8% vs. 75.3%, p=0.001).
- ≥2 positive cultures at resection was identified as a significant risk factor for failure in both univariate (OR 7.55) and multivariable (OR 8.12) analyses.
Conclusions:
- The number of positive intraoperative cultures at resection is a significant prognostic indicator in PJI.
- Having ≥2 positive cultures at resection increases the risk of treatment failure by over eightfold in patients undergoing 2-stage exchange.
- This finding highlights the importance of intraoperative culture results for predicting PJI treatment success.
