Trends in Revision Hip Arthroplasty for Prosthetic Joint Infection: A Single-Center Study of 423 Hips at a High-Volume Center Between 2008 and 2021

Socioeconomic Disadvantage Predicts Decreased Likelihood of Maintaining a Functional Knee Arthroplasty Following Treatment for Prosthetic Joint Infection

BACKGROUND

Prosthetic joint infection (PJI) carries major morbidity and mortality as well as a complicated and lengthy treatment course. In patients who have high degrees of socioeconomic disadvantage, this may be a particularly devastating complication. Our study sought to evaluate the impact of socioeconomic deprivation on outcomes following treatment for PJI of the knee.

METHODS

We conducted a retrospective review of revision total knee arthroplasty (TKA) procedures performed for the treatment of initial PJI between 2008 and 2020 at a single tertiary care center in the United States. The Area Deprivation Index (ADI) was used to quantify socioeconomic deprivation. The primary outcome measure was presence of a functional knee joint at the time of most recent follow-up defined as TKA components or an articulating spacer. A total of 96 patients were included for analysis. The median follow-up duration was 26.5 months.

RESULTS

There was no significant difference in the rate of treatment failure (P = .63). However, the proportion of patients who had a functional knee arthroplasty (in contrast to having undergone arthrodesis, amputation, or retention of a static spacer) declined significantly with increasing ADI index (81.8% for the least disadvantaged group, 58.7% for the middle group, 42.9% for the most disadvantaged group, P = .021).

CONCLUSIONS

Patients who have a higher socioeconomic disadvantage as measured by ADI are less likely to maintain a functional knee arthroplasty following treatment for TKA PJI. These findings support continued efforts to improve access to care and optimize treatment plans for patients who have socioeconomic disadvantage.

KLIC Score Does Not Predict Failure After Early Prosthetic Joint Infection: An External Validation With 153 Knees and 130 Hips

BACKGROUND

A preoperative risk score, the KLIC score (chronic renal failure [K], liver cirrhosis [L], indication of the index surgery [I], cemented prosthesis [C], and C-reactive protein >115 mg/L), has been developed to predict the risk of treatment failure after early prosthetic joint infection (PJI). This study aimed to validate the KLIC score for the debridement, antibiotics, and implant retention (DAIR) procedure and one-stage revisions in a Northern European cohort.

METHODS

Revisions due to early PJI of the hip or knee between January 1, 2008, and September 12, 2021, were identified retrospectively. The primary outcome was early failure, which was considered when the patient needed an unscheduled surgery, the patient died, or the patient was prescribed long-term suppressive antibiotics. To examine the association between KLIC score and failure risk, univariable logistic regression with area under the curve (AUC) was used. In addition, models were calibrated to assess prognostic ability and clinical utility was examined with decision-curve analyses.

RESULTS

An increase in KLIC score had a moderate predictive value for early failure after DAIR (odds ratio [OR] 1.45; confidence interval [CI] 1.13 to 1.90). For one-stage revision, it was only slightly predictive of failure (OR 1.20; CI 0.93 to 1.56). After 60 days, the AUC for DAIR was 0.63 (CI 0.55 to 0.72) and 0.56 (CI 0.46 to 0.66) for one-stage revisions, indicating poor discriminative ability. The decision-curve analyses revealed that the model did not offer a remarkable net benefit across a range of threshold probabilities.

CONCLUSIONS

We demonstrated that the KLIC score is not a reliable predictor of early failure after early PJI in a Northern European cohort. Using the model to guide treatment decisions does not provide any additional clinical utility beyond the baseline strategies.

Cobalt and Chromium Ions Impair Macrophage Response to Staphylococcus aureus Infection

Cobalt-chromium-molybdenum (CoCrMo) alloys are routinely used in arthroplasty. CoCrMo wear particles and ions derived from arthroplasty implants lead to macrophage-driven adverse local tissue reactions, which have been linked to an increased risk of periprosthetic joint infection after revision arthroplasty. While metal-induced cytotoxicity is well characterized in human macrophages, direct effects on their functionality have remained elusive. Synchrotron radiation X-ray microtomography and X-ray fluorescence mapping indicated that peri-implant tissues harvested during aseptic revision of different arthroplasty implants are exposed to Co and Cr in situ. Confocal laser scanning microscopy revealed that macrophage influx is predominant in patient tissue. While in vitro exposure to Cr3+ had only minor effects on monocytes/macrophage phenotype, pathologic concentrations of Co2+ significantly impaired both, monocyte/macrophage phenotype and functionality. High concentrations of Co2+ led to a shift in macrophage subsets and loss of surface markers, including CD14 and CD16. Both Co2+ and Cr3+ impaired macrophage responses to Staphylococcus aureus infection, and particularly, Co2+-exposed macrophages showed decreased phagocytic activity. These findings demonstrate the immunosuppressive effects of locally elevated metal ions on the innate immune response and support further investigations, including studies exploring whether Co2+ and Cr3+ or CoCrMo alloys per se expose the patients to a higher risk of infections post-revision arthroplasty.