Septic Failure After One-Stage Exchange for Prosthetic Joint Infection of the Hip: Microbiological Implications.

BACKGROUND: The microbiological implications of septic failure after 1-stage exchange for prosthetic joint infection (PJI) of the hip remain unclear. METHODS: Information was gathered on comorbidities, previous procedures, preoperative and postoperative microbiology results, methods of detection, and antibiotic resistance patterns, for all patients, who developed septic failure after 1-stage exchange for PJI of the hip performed at our institution during 2001-2017. RESULTS: Seventy-seven patients were identified. Septic failure was diagnosed a mean of 1.7 (standard deviation 2.3, range 0-11.8) years later. Although the spectrum of microorganisms was similar to preoperative, in the majority of patients (55%), the initial microorganism(s) was (were) replaced by (a) totally different microorganism(s). Overall, there was a decrease in the number of polymicrobial PJIs. The number of patients with high virulent microorganisms decreased significantly from 52 to 36 (P = .034). The number of PJIs due to gram-negative pathogens remained similar (11 vs 14, P = .491). The number of rifampicin-resistant staphylococci, fluoroquinolone-resistant streptococci, enterococci, and fungi changed from 8 to 15, 0 to 2, 7 to 3, and 1 to 2, respectively, but these changes did not reach statistical significance. CONCLUSION: The majority of reinfections is caused by different infecting bacteria, hence it is essential to perform a new diagnostic workup and not base treatment decisions (solely) on historical cultures. We were furthermore unable to irrefutably prove that, from a microbiological point of view, septic failure after 1-stage exchange comes with increased challenges. Given the time interval to failure, we propose that a longer follow-up of these patients is needed, than previously suggested.

What is the rate of reinfection with different and difficult-to-treat bacteria after failed one-stage septic knee exchange?

PURPOSE: Re-operation after septic failure of a one-stage exchange for prosthetic joint infection (PJI) of the knee is a highly challenging procedure with concerns over residual bone stock, soft tissues, and stability. The associated changes in microbiology in cases of reinfection are still largely unknown. METHODS: A comprehensive analysis was performed of all patients treated at our tertiary institution between 2001 and 2017 who developed reinfection after a one-stage exchange for PJI of the knee. Prerequisites for inclusion were a certain diagnosis of PJI according to the ICM criteria and a minimum follow-up of three years. Data on comorbidities, previous surgical interventions, microbiological findings at the time of the initial one-stage exchange and at the time of reinfection, detection methods, and antibiotic resistance patterns were retrospectively studied. RESULTS: Sixty-six patients were identified that met the inclusion criteria. Reinfection occurred after a mean time interval of 27.7 months (SD ± 33.9, range 1-165). Ten types of bacteria were found that were not present before the one-stage exchange. The causative pathogen remained identical in 22 patients (33%) and additional microorganisms were detected in ten patients (15%). Half of the reinfections were however due to (a) completely different microorganism(s). A significant increase in the number of PJIs on the basis of high-virulent (23 vs 30, p = 0.017) and difficult-to-treat bacteria (13 vs 24, p = 0.035) was found. CONCLUSION: The present study provides a novel insight into the microbiological changes following septic failure after one-stage exchange for PJI of the knee. A higher prevalence of more difficult-to-treat bacteria might increase the complexity of subsequent procedures. Also, a longer follow-up of these patients than previously suggested seems in order.

Risk factors for aseptic loosening in complex revision total knee arthroplasty using rotating hinge implants.

PURPOSE: This study aimed to determine the risk factors of aseptic loosening (AL) in complex revision total knee arthroplasty (TKA) cases using rotating hinge knee prosthesis. METHODS: Patients who had undergone re-revision rotating hinge prosthesis surgery between January 2012 and December 2017 were included. Parameters related to AL were retrospectively reviewed. For this purpose, 31 aseptic loosening patients and 30 control patients were included in the study. Various risk factors were evaluated. Risk factors for AL after re-revision were determined using univariate and multiple logistic regression analyses. RESULTS: Thirty-one AL patients and 30 control patients were included. In the AL group, tibial tantalum cone and impaction grafting were performed significantly less frequently than the control group (p = 0.002 and p < 0.001). Logistic regression analysis revealed that smoking, right-sided TKA, and large femoral canal anteroposterior diameter were factors that increased the risk of AL after re-revision, while tibial tantalum cone decreased the risk of loosening. Smokers had an 11.847-fold higher risk for AL; right-sided TKA led to a 4.594-fold higher risk for AL. However, the presence of a tibial tantalum cone was associated with an 8.403-fold lower risk for AL. CONCLUSIONS: We conclude that smoking, right-sided prosthesis, and large femoral canal diameter increased the risk of AL, while tantalum cone and impaction grafting reduced this risk in patients who underwent re-revision surgery with rotating hinge prosthesis after TKA.