Development and Evaluation of a Prognostic Calculator for the Surgical Treatment of Periprosthetic Joint Infection

Clinical prediction models to guide treatment of periprosthetic joint infections: A systematic review and meta-analysis

BACKGROUND

Several clinical prediction models that aim to guide decisions about the management of periprosthetic joint infections (PJI) have been developed. While some models have been recommended for use in clinical settings, their suitability remains uncertain.

METHODS

We systematically reviewed and critically appraised all multivariable prediction models for the treatment of PJI. We searched MEDLINE, EMBASE, Web of Science, and Google Scholar from inception until March 1st, 2024 and included studies that developed or validated models that predict the outcome of PJI. We used PROBAST (Prediction model Risk Of Bias ASsessment Tool) to assess the risk of bias and applicability. Model performance estimates were pooled via random effect meta-analysis.

RESULTS

Thirteen predictive models and seven external validations were identified. Methodological issues were identified in all studies. Pooled estimates indicated that the KLIC (Kidney, Liver, Index surgery, Cemented prosthesis, C-reactive protein) score had fair discriminative performance (pooled c-statistic 0.62, 95% CI 0.55 to 0.69). Both the τ2 (0.02) and I2 (33.4) estimates indicated that between study heterogeneity was minimal. Meta-analysis indicated Shohat et al's model had good discriminative performance (pooled c-statistic 0.74, 95% CI 0.57 to 0.85). Both the τ2 (0.0) and I2 (0.0) indicated that between study heterogeneity was minimal.

CONCLUSIONS

Clinicians should be aware of limitations in the methods used to develop available models to predict outcomes of PJI. As no models have consistently demonstrated adequate performance across external validation studies, it remains unclear if any available models would provide reliable information if used to guide clinical decision-making.

Risk factors of recurrent periprosthetic joint infection of the knee after two-stage reimplantation

INTRODUCTION

Prosthetic joint infection (PJI) is one of the most common and detrimental complications of total knee replacement arthroplasty (TKA). Despite extensive efforts, including two-stage reimplantation, to eradicate PJI, it still recurs in a substantial number of patients. However, the risk factors of recurrence after two-stage reimplantation of the knee have not been established. In this study, it is hypothesized that there will be certain risk factors of recurrence after two-stage reimplantation for PJI of the knee.

MATERIALS AND METHODS

From March 2002 to December 2022, 65 knees that underwent two-stage reimplantation for PJIs in a single, tertiary hospital were retrospectively reviewed, and 44 patient-related, laboratory-related, and surgery-related factors, including body mass index, pathogen type, and the usage of transfusions, were selected as the potential risk factors for recurrence. Survival analysis using the Kaplan-Meier method and subsequent Cox proportional hazard regression were performed.

RESULTS

Out of the 65 knees that underwent two-stage reimplantation, infection recurred in 15 knees (23.1%) in a median 11 (range 4-108) months. The Cox proportional hazards regression showed that infection of revision TKA, mixed pathogen-type infection, and higher serum erythrocyte sedimentation rate (ESR, mm/h) level increases the risk of recurrence (p-values < 0.001, 0.04, and 0.009; hazard ratios 40.29, 1.53, and 1.03, respectively).

CONCLUSIONS

A significant portion of PJI of the knees recurred after two-stage reimplantation. Revision TKA at the time of initial PJI, mixed pathogen-type infection, and higher serum ESR level were three significant risk factors of PJI recurrence. Surgeons should be more cautious in suspecting PJI relapse for these specific occasions.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Methodological Challenges in Predicting Periprosthetic Joint Infection Treatment Outcomes: A Narrative Review

The management of periprosthetic joint infection (PJI) generally requires both surgical intervention and targeted antimicrobial therapy. Decisions regarding surgical management–whether it be irrigation and debridement, one-stage revision, or two-stage revision–must take into consideration an array of factors. These include the timing and duration of symptoms, clinical characteristics of the patient, and antimicrobial susceptibilities of the microorganism(s) involved. Moreover, decisions relating to surgical management must consider clinical factors associated with the health of the patient, alongside the patient's preferences. These decisions are further complicated by concerns beyond mere eradication of the infection, such as the level of improvement in quality of life related to management strategies. To better understand the probability of successful surgical treatment of a PJI, several predictive tools have been developed over the past decade. This narrative review provides an overview of available clinical prediction models that aim to guide treatment decisions for patients with periprosthetic joint infection, and highlights key challenges to reliably implementing these tools in clinical practice.

Obesity, Comorbidities, and Prior Operations Additively Increase Failure in 2-Stage Revision Total Knee Arthroplasty for Prosthetic Joint Infection

BACKGROUND

Prosthetic joint infection (PJI) of the knee carries significant morbidity, mortality, and economic cost. We hypothesize that obese and poor medical hosts will have a significant and additive increase in failure rate undergoing 2-stage revision total knee arthroplasty for PJI.

METHODS

All 2-stage revision total knee arthroplasty procedures for PJI performed at one institution were identified between 2005 and 2020. In total, 144 patients were included and defined as success or failure based on published criteria regarding infection eradication, further intervention, or mortality. The American Society of Anesthesiologists score and the Charlson Comorbidity Index were utilized to assess host grade. Patient, surgical, and microbiologic variables were investigated with univariable and multivariable analysis to explore association with risk of failure.

RESULTS

In the cohort, 32.4% of patients failed with mean follow-up of 5.1 years. In multivariable analysis, the number of major operations requiring arthrotomy and implantation of new material between the primary and first stage, host grade, and elevated body mass index were the major contributors to failure. Combining these factors, with body mass index >30 and 2 or more major operations, the failure rate increased to 76.5% and 71.4% respectively for American Society of Anesthesiologists score 3 (P ≤ .001) and Charlson Comorbidity Index ≥2 (P ≤ .001).

CONCLUSION

In this cohort, multiple major operations between the primary and first stage, host grade, and obesity were the major contributors to failure. When combining these factors, patients had an additive increase in failure rate. Treatments such as amputation or less invasive options and suppression should be discussed and considered in these patients.

Repeat two-stage revision for knee prosthetic joint infection results in very high failure rates

INTRODUCTION

Two stage revision total knee arthroplasty (TKA) is the gold standard for treatment and eradication of knee prosthetic joint infections (PJI), but the literature is limited on the outcomes of repeat two-stage TKA after PJI recurrence. This study presents the outcomes of repeat two-stage revision TKA and investigates potential factors contributing to success or failure, aiming to assist counselling and decision-making.

METHODS

A retrospective study was undertaken investigating all two-stage revision TKA performed at one institution between 2005 and 2020. Twenty cases underwent repeat two-stage revision TKA. Patient outcomes and factors contributing to treatment success or failure were investigated. PJI was diagnosed according to MSIS criteria.

RESULTS

Of the 20 cases, 14 were classified as failed treatment (70%) due to a failure to eradicate infection, further surgical intervention or death. In this cohort, there were no statistically significant differences between the groups regarding factors contributing to treatment success or failure. In the success group, patient reported functional outcomes were variable.

CONCLUSION

This study demonstrates that patients undergoing a repeat two-stage TKA have very poor outcomes. This study did not identify any factors that predicted failure. Patients need to be counselled regarding poor outcomes with repeat two-stage TKA, and other treatment options such as early amputation or lifelong suppression should be considered.

Systematic review of risk prediction studies in bone and joint infection: are modifiable prognostic factors useful in predicting recurrence?

Background: Classification systems for orthopaedic infection include patient health status, but there is no consensus about which comorbidities affect prognosis. Modifiable factors including substance use, glycaemic control, malnutrition and obesity may predict post-operative recovery from infection. Aim: This systematic review aimed (1) to critically appraise clinical prediction models for individual prognosis following surgical treatment for orthopaedic infection where an implant is not retained; (2) to understand the usefulness of modifiable prognostic factors for predicting treatment success. Methods: EMBASE and MEDLINE databases were searched for clinical prediction and prognostic studies in adults with orthopaedic infections. Infection recurrence or re-infection after at least 6 months was the primary outcome. The estimated odds ratios for the primary outcome in participants with modifiable prognostic factors were extracted and the direction of the effect reported. Results: Thirty-five retrospective prognostic cohort studies of 92 693 patients were included, of which two reported clinical prediction models. No studies were at low risk of bias, and no externally validated prediction models were identified. Most focused on prosthetic joint infection. A positive association was reported between body mass index and infection recurrence in 19 of 22 studies, similarly in 8 of 14 studies reporting smoking history and 3 of 4 studies reporting alcohol intake. Glycaemic control and malnutrition were rarely considered. Conclusion: Modifiable aspects of patient health appear to predict outcomes after surgery for orthopaedic infection. There is a need to understand which factors may have a causal effect. Development and validation of clinical prediction models that include participant health status will facilitate treatment decisions for orthopaedic infections.

External Validation Demonstrates Limited Clinical Utility of a Preoperative Prognostic Calculator for Periprosthetic Joint Infection

BACKGROUND

Preoperative calculation of treatment failure risk in patients undergoing surgery for periprosthetic joint infection (PJI) is imperative to allow for medical optimization and targeted prevention. A preoperative prognostic model for PJI treatment failure was previously developed, and this study sought to externally validate the model.

METHODS

A retrospective review was performed of 380 PJIs treated at two institutions. The model was used to calculate the risk of treatment failure, and receiver operating characteristic curves were generated to calculate the area under the curve (AUC) for each institution.

RESULTS

When applying this model to institution 1, an AUC of 0.795 (95% confidence interval [CI]: 0.693-0.897) was found, whereas institution 2 had an AUC of 0.592 (95% CI: 0.502-0.683). Comparing all institutions in which the model had been applied to, we found institution 2 represented a significantly sicker population and different infection profile.

CONCLUSION

In this cohort study, we externally validated the prior published model for institution 1. However, institution 2 had a decreased AUC using the prior model and represented a sicker and less homogenous cohort compared with institution 1. When matching for chronicity of the infection, the AUC of the model was not affected. This study highlights the impact of comorbidities and their distributions on PJI prognosis and brings to question the clinical utility of the algorithm which requires further external validation.

Synovial Alpha-defensin at Reimplantation in Two-stage Revision Arthroplasty to Rule Out Persistent Infection

BACKGROUND/AIM

Owing to the lack of a diagnostic gold standard, ruling out persistent periprosthetic joint infection (PJI) before second-stage surgery in the setting of two-stage revision arthroplasty constitutes a major challenge. We evaluated if the alpha-defensin-1 (AD-1) test could predict successful infection eradication before reimplantation of a new prosthesis.

PATIENTS AND METHODS

Our prospective study included 20 patients who underwent two-stage revision arthroplasty for treatment of PJI. A standard quantitative enzyme AD-1 immunoassay of synovial fluid, the synovial leukocyte esterase test and routine laboratory blood testing were performed prior to explantation and reimplantation. Treatment failure was defined according to the Delphi-based consensus criteria after a minimum follow-up of 1 year.

RESULTS

A 15% of our patients met the Delphi Criteria within 1 year. None of the markers investigated were significantly different in patients with and without reinfection.

CONCLUSION

Further research is necessary to identify biomarkers more suitable for indicating persistent infection before reimplantation.

Trends in the treatment of infected knee arthroplasty

Essential treatment methods for infected knee arthroplasty involve DAIR (debridement, antibiotics, and implant retention), and one and two-stage exchange arthroplasty.Aggressive debridement with the removal of all avascular tissues and foreign materials that contain biofilm is mandatory for all surgical treatment modalities.DAIR is a viable option with an acceptable success rate and can be used as a first surgical procedure for patients who have a well-fixed, functioning prosthesis without a sinus tract for acute-early or late-hematogenous acute infections with no more than four weeks (most favourable being < seven days) of symptoms. Surgeons must focus on the isolation of the causative organism with sensitivities to bactericidal treatment as using one-stage exchange.One-stage exchange is indicated when the patients have:minimal bone loss/soft tissue defect allowing primary wound closure,easy to treat micro-organisms,absence of systemic sepsis andabsence of extensive comorbidities.There are no validated serum or synovial biomarkers to determine optimal timing of re-implantation for two-stage exchange.Antibiotic-free waiting intervals and joint aspiration before the second stage are no longer recommended. The decision to perform aspiration should be made based on the index of suspicion for persistent infection.Re-implantation can be performed when the treating medical team feels that the clinical signs of infection are under control and serological tests are trending downwards. Cite this article: EFORT Open Rev 2020;5:672-683. DOI: 10.1302/2058-5241.5.190069.

Aspirin administration might accelerate the subsidence of periprosthetic joint infection

Since the past decade, aspirin, a popular anti-inflammatory drug, has been increasingly studied for its potential antimicrobial and antibiofilm activity with promising results, but studies were limited to in vitro and in vivo investigations. Moreover, evidence concerning the beneficial effects of aspirin on the treatment of biofilm-related infections in real-world population is limited. Thus, this study aimed to investigate whether aspirin could promote infection control for patients with periprosthetic joint infections (PJIs). A single-center database was searched. Regular aspirin exposure was defined as a prescription of aspirin for > 6 months before diagnosis of PJIs and consecutive use during the PJI treatment course at a dose ≧ 100 mg/day. General data, treatment modalities, and recurrence status were collected from medical records by an independent orthopedic surgeon. From January 01, 2010, to February 17, 2019, 88 patients who met the PJI criteria were identified and included in this study. Of these patients, 12 were taking aspirin regularly during the infectious events. In the Cox proportional hazards model, multivariate analysis revealed that the aspirin group demonstrated significant benefit via superior resolution of PJIs (HR 2.200; 95% CI 1.018-4.757; p = 0.045). In this study, aspirin is beneficial for infection resolution when combined with the current standard of PJI treatment and conventional antibiotics in the management of PJIs.

The Dark Side of Arthroplasty: Competing Risk Analysis of Failed Hip and Knee Arthroplasty With Periprosthetic Joint Infection

BACKGROUND

Increasing total hip (THA) and knee (TKA) arthroplasties inevitably lead to accumulating failed arthroplasty (FA) with periprosthetic joint infections (PJI) and definite treatment recommendations are scarce. Our aims were to evaluate patient and infection site specific risk factors, and to identify case-dependent salvage procedure recommendations.

METHODS

Retrospective analysis was conducted of salvage procedures for FA after PJI (amputation, Girdlestone resection arthroplasty [GRA], arthrodesis, or chronic fistulation [CF]) from 2008 to 2018. Univariable and multivariable modeling of revision and mortality rates, using cumulative incidence competing risk analysis, and Cox proportional hazards models were calculated.

RESULTS

In total, 135 patients (THA 62%; TKA 38%) were diagnosed for FA after PJI, having undergone an average of 3 [1-4] revisions at a mean follow-up of 12.8 [7.8-20.9] years. Forty-four percent of THAs and 55% of TKAs had to be revised following FA, 44% deceased during follow-up, and 16% could be reconverted to an infection-free arthroplasty. GRA revealed significantly higher revision rates than CF (P = .015) for THA. Lower age (P = .003), higher number of revisions before FA (P = .007), more than one microorganism at infection site (P = .034), and GRA (P = .037, only THA) prevailed independent risk factors for revision. Patients' age remained an independent mortality risk factor (P = .001).

CONCLUSION

High-risk patients suffering from FA after THA with poor constitution profit from controlled constitution of CF, reducing the risk for revision surgeries and hospitalization. In case of FA after TKA, data did not allow definite treatment recommendations. We believe that education concerning amputation should be considered early after multiple TKA revisions.

Reporting Outcomes of Treatment for Periprosthetic Joint Infection of the Knee and Hip Together With a Minimum 1-Year Follow-Up is Reliable

BACKGROUND

Although there is an increasing trend toward reporting the outcome of hip and knee arthroplasty separately, it remains unknown whether joint-specific reporting is necessary for periprosthetic joint infection (PJI) as sample sizes are already low, given its relatively rare occurrence. The aim of this study is to compare treatment outcomes of PJI occurring after knee and hip arthroplasty. Furthermore, we aim to establish the necessary follow-up time for an accurate reporting of PJI treatment outcomes.

METHODS

A retrospective study of 792 cases of hip and knee PJI treated with irrigation and debridement or two-stage exchange arthroplasty from 2000 to 2017 was performed. Treatment failure was defined based on the Delphi method-based criteria. The Kaplan-Meier survivorship curves were generated, and a log-rank test was used to evaluate differences in survivorship. A multivariate Cox proportional hazards regression and a sensitivity analysis using propensity matching were performed. A two-piecewise linear regression model was used to examine the threshold effect of time after treatment on survival rates.

RESULTS

There were no significant differences between hip and knee PJIs in overall survivorship (P = .71), or when stratified by irrigation and debridement (P = .39), or two-stage exchange arthroplasty (P = .59). There was also no difference by joint in the multivariate or sensitivity analysis. Survival rates had the most dramatic rates of decrease in the initial months after treatment of PJI but began to plateau after 1.09 years.

CONCLUSION

This study reveals no difference in treatment outcomes between knee and hip PJIs. In addition, given the difficulty with obtaining follow-up, we suggest that one-year follow-up is sufficient for an accurate reporting of treatment failure.

Is Treatment of Periprosthetic Joint Infection Improving Over Time?

BACKGROUND

It is unknown whether the outcomes of treatment for periprosthetic joint infection (PJI) are improving with time. This study evaluated trends in PJI treatment outcomes in the hip and knee following 2-stage exchange arthroplasty and irrigation and debridement (I&D) over the last 17 years.

METHODS

We reviewed 550 two-stage exchange arthroplasties and 194 I&Ds between 2000 and 2016 at our institution. Treatment success was defined according to the Delphi consensus criteria and Kaplan-Meier survivorship curves were generated. A multivariate Cox proportional hazards regression model was generated to determine time trends in the outcome of PJI treatment with the year of surgery included as both a continuous covariate (per 1-year increase) and a categorical covariate (2000-2010 or 2011-2016).

RESULTS

The survivorship of I&D, 2-stage revision, and the total combined cohort were comparable between 2000-2010 and 2011-2016 groups. Multivariate Cox regression analysis showed that the year of surgery was not associated with treatment failure following an I&D or 2-stage exchange arthroplasty, and neither did it increase the risk of non-reimplantation. When year of surgery was considered as a categorical variable, there remained no significant difference in treatment failure following an I&D or 2-stage exchange arthroplasty between the 2000-2010 cohort and 2011-2016 cohort.

CONCLUSION

Despite the increasing clinical focus, research advances, and growing literature relating to PJI, we were unable to detect any substantial improvement in the treatment success rates of PJI at our institution over the 17 years examined in this study. Novel treatments and techniques are certainly needed as current and prior strategies remain far from optimal.

Analysis and Review of Automated Risk Calculators Used to Predict Postoperative Complications After Orthopedic Surgery

PURPOSE OF REVIEW

To discuss the automated risk calculators that have been developed and evaluated in orthopedic surgery.

RECENT FINDINGS

Identifying predictors of adverse outcomes following orthopedic surgery is vital in the decision-making process for surgeons and patients. Recently, automated risk calculators have been developed to quantify patient-specific preoperative risk associated with certain orthopedic procedures. Automated risk calculators may provide the orthopedic surgeon with a valuable tool for clinical decision-making, informed consent, and the shared decision-making process with the patient. Understanding how an automated risk calculator was developed is arguably as important as the performance of the calculator. Additionally, conveying and interpreting the results of these risk calculators with the patient and its influence on surgical decision-making are paramount. The most abundant research on automated risk calculators has been conducted in the spine, total hip and knee arthroplasty, and trauma literature. Currently, many risk calculators show promise, but much research is still needed to improve them. We recommend they be used only as adjuncts to clinical decision-making. Understanding how a calculator was developed, and accurate communication of results to the patient, is paramount.

Increased Postoperative Glucose Variability Is Associated With Adverse Outcome Following Two-Stage Exchange Arthroplasty for Periprosthetic Joint Infection

BACKGROUND

Glucose variability in the postoperative period has been associated with increased rates of periprosthetic joint infection (PJI) following primary arthroplasty. It is unknown how postoperative glucose control affects outcome of surgical treatment of PJI patients. We hypothesized that postoperative glucose variability adversely affects the outcome of 2-stage exchange arthroplasty.

METHODS

We retrospectively reviewed records of 665 patients with PJI of the knee and hip who underwent 2-stage exchange arthroplasty from 2000 to 2017. Of them, 341 PJIs with a minimum follow-up of 1 year, and either a minimum of 2 glucose values per day or greater than 3 overall during the reimplantation were included. Glucose variability was assessed by calculating the coefficient of variation. Adverse outcomes included treatment failure according to the Delphi consensuses criteria, reinfection, reoperation, and mortality. A subgroup analysis was performed based on patients with or without diabetes.

RESULTS

Glucose variability following reimplantation was associated with higher treatment failure, reinfection, and reoperation. Adjusted analysis indicated that for every standard deviation (15%) increase in the coefficient of variation, the risks of treatment failure, reinfection, and reoperation increased by 27%, 31%, and 26%. Although stratifying patients with (n = 81) or without diabetes (n = 260), these associations remained robust in nondiabetic patients, but not in diabetic patients.

CONCLUSION

Higher glucose variability is associated with increased risks of treatment failure, reinfection, and reoperation after 2-stage exchange arthroplasty in PJI patients. Compared to diabetic patients, nondiabetic patients have a higher association between glucose variability and poor outcomes. Reducing adverse outcomes may be achieved with close monitoring and strict postoperative glucose control.

Surgical Treatment of Chronic Periprosthetic Joint Infection: Fate of Spacer Exchanges

BACKGROUND

Patients with periprosthetic joint infection (PJI) undergoing 2-stage exchange arthroplasty may undergo an interim spacer exchange for a variety of reasons including mechanical failure of spacer or persistence of infection. The objective of this study is to understand the risk factors and outcomes of patients who undergo spacer exchange during the course of a planned 2-stage exchange arthroplasty.

METHODS

Our institutional database was used to identify 533 patients who underwent a 2-stage exchange arthroplasty for PJI, including 90 patients with a spacer exchange, from 2000 to 2017. A retrospective review was performed to extract relevant clinical information. Treatment outcomes included (1) progression to reimplantation and (2) treatment success as defined by a Delphi-based criterion. Both univariate and multivariate Cox regression models were performed to investigate whether spacer exchange was associated with failure. Additionally, a propensity score analysis was performed based on a 1:2 match.

RESULTS

A spacer exchange was required in 16.9%. Patients who underwent spacer exchanges had a higher body mass index (P < .001), rheumatoid arthritis (P = .018), and were more likely to have PJI caused by resistant (0.048) and polymicrobial organisms (P = .007). Patients undergoing a spacer exchange demonstrated lower survivorship and an increased risk of failure in the multivariate and propensity score matched analysis compared to patients who did not require a spacer exchange.

DISCUSSION

Despite an additional load of local antibiotics and repeat debridement, patients who underwent a spacer exchange demonstrated poor outcomes, including failure to undergo reimplantation and twice the failure rate. The findings of this study may need to be borne in mind when managing patients who require spacer exchange.

Positive Alpha-defensin at Reimplantation of a Two-stage Revision Arthroplasty Is Not Associated with Infection at 1 Year

BACKGROUND

Diagnosing periprosthetic joint infection (PJI) represents a challenge that relies on multiple clinical and laboratory criteria that may not be consistently present. The synovial alpha-defensin-1 (AD-1) test has been shown to correlate accurately with the Musculoskeletal Infection Society (MSIS) criteria for the diagnosis of PJI, however, its association with persistent PJI has not been elucidated in the setting of patients receiving antibiotic spacers during second-stage reimplantation. Applying a Delphi-based consensus to define successful eradication of PJI offers an opportunity to test the utility of AD-1 in this setting.

QUESTIONS/PURPOSES

(1) Can the AD-1 test determine whether infection has been controlled using the Delphi criteria for persistent PJI as a surrogate for infection eradication during two-stage revision for PJI treatment with a spacer? (2) How does the performance of the AD-1 test compare with the MSIS criteria?

METHODS

This was a multicenter analysis of retrospectively collected data on patients who underwent a two-stage revision arthroplasty between May 2014 and July 2016. We included patients who had a previously confirmed PJI and received a cement spacer, underwent the second stage, had MSIS criteria data and a synovial fluid AD-1 test, and had a minimum followup of 1 year. We were unable to determine for all study sites how many patients had the test but did not meet all the criteria and so could not be studied; however, we were able to identify 69 patients (43 knees, 26 hips) who met all criteria. During the period in question, indications for use of AD-1 varied by surgeon; however, during that time, in general if a surgeon ordered it as part of the initial workup, the test would have been repeated before the second-stage reimplantation procedure. To assess the validity of AD-1 against persistence of PJI criteria at 1 year, the following were calculated using the Delphi criteria for persistent PJI as the gold standard: sensitivity, specificity, positive and negative predictive values, accuracy, and area under the curve (AUC) with 95% confidence intervals (CIs). Concordance index (c-index) and its Wald 95% CI with receiver operating characteristic (ROC) curve were calculated in relation to Delphi criteria for persistent PJI using AD-1 and then MSIS criteria. The two c-indices of AD-1 and MSIS were compared using the DeLong nonparametric approach.

RESULTS

The AD-1 test showed poor sensitivity (7%; 95% CI, 0.2-34), and poor overall accuracy (73%; 95% CI, 60-83; AUC = 0.5; 95% CI, 0.3-0.6) in detecting infection eradication at 1 year. The c-index for AD-1 versus Delphi criteria for persistent PJI was 0.519 (95% CI, 0.44-0.60), and the c-index for MSIS criteria versus Delphi criteria for persistent PJI was 0.518 (95% CI, 0.49-0.54), suggesting the weak diagnostic abilities of these models. The contrast estimate between MSIS criteria and AD-1 were not different from one another at -0.001 (95% CI%, -0.09 to 0.09; p = 0.99).

CONCLUSIONS

We found that a positive synovial fluid AD-1 test correlated poorly with the presence of persistent infection 1 year after two-stage revision arthroplasty for PJI. For this reason, we recommend against the routine use of AD-1 in patients with cement spacers, until or unless future studies demonstrate that the test is more effective than we found it to be.

LEVEL OF EVIDENCE

Level IV, diagnostic study.

Outcomes and predictors of treatment failure following two-stage total joint arthroplasty with articulating spacers for evolutive septic arthritis

Background

The treatment strategy for evolutive septic arthritis (SA) with coexistent degenerative joint disease is not well established. The purposes of this study were to 1) investigate treatment outcome and potential risk factors of treatment failure in patients with evolutive SA following two-stage procedure, including insertion of an antibiotic-loaded spacer at the first stage and subsequent implantation of a new prosthesis; and 2) determine the performance of serum erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and Interleukin-6 (IL-6) in predicting persisting infection at second-stage procedure.

Methods

We retrospectively reviewed 74 patients with evolutive SA of hips and knees who underwent a two-stage TJA between 2008 and 2015. The treatment success was defined according to the modified Delphi criteria and Kaplan-Meier survivorship curves were constructed to determine treatment success. A Cox regression model was performed to identify risk factors for treatment failure. Receiver operating characteristic (ROC) curves were generated to determine the prognostic value of ESR, CRP, and IL-6 in predicting persistent infection before second-stage prostheses implantation.

Results

Overall, the treatment success rate was 93% for hips and 100% for knees after the first-stage surgery. The treatment success rate was 89% for hips and 84% for knees after second-stage prosthesis implantation with a mean follow-up of 4.7 (range, 2.2 to 10.8) years. Older age (Hazard ratio [HR] [per 10-year increase], 1.20; 95% confidential interval [CI], 1.11 to 1.62), higher preoperative CRP level (HR [per 1-mg/dL increase], 1.15; 95% CI, 1.04 to 1.28) and resistant organism (HR, 13.96; 95% CI, 3.29 to 19.20) were associated with an increased risk of treatment failure. All serologic tests presented limited values in predicting persisting infection, with the area under ROC curve of ESR, CRP, IL-6 and combination of the three markers was 57.8, 61.6, 60.3, and 62.1%, respectively.

Conclusions

Two-stage TJA is an adequate management of infection control in patients with evolutive SA. The three potential risk factors (old age, high preoperative CRP, and resistant organism profile) may predict treatment failure following a two-stage procedure for evolutive SA. Additionally, serum ESR, CRP, and IL-6 had no benefit in predicting persisting infection before second-stage prostheses implantation. These findings may be useful when treating patients with evolutive SA.

New 5-Factor Modified Frailty Index Predicts Morbidity and Mortality in Primary Hip and Knee Arthroplasty

BACKGROUND

While the 11-factor modified frailty index (mFI) has been shown to predict adverse outcomes in patients undergoing total joint arthroplasty, the 5-factor index has not been evaluated in this patient population. The goal of this study was to evaluate the utility of the mFI-5 as a predictor of morbidity and mortality in patients undergoing primary total hip and knee arthroplasty.

METHODS

A retrospective analysis of the American College of Surgeons National Surgical Quality Improvement Program's database for patients undergoing total hip arthroplasty and total knee arthroplasty between the years 2005 and 2016 was conducted. The 5-factor score, which includes the presence of comorbid diabetes, hypertension, congestive heart failure, chronic obstructive pulmonary disease, and functional status, was calculated for each patient. Multivariate logistic regression models were used to assess the relationship between the mFI-5 and postoperative complications while controlling for demographic variables.

RESULTS

One hundred forty thousand one hundred fifty-eight patients undergoing total hip arthroplasty and 226,398 patients undergoing total knee arthroplasty were identified. After adjusting for demographic variables and comorbid conditions, logistic regression analyses revealed that the mFI-5 was a strong predictor for total complications, Clavien-Dindo grade IV complications (cardiac arrest, myocardial infarction, septic shock, pulmonary embolism, postoperative dialysis, reintubation, and prolonged ventilator requirement), surgical site infections, readmission, and 30-day mortality (P < .001).

CONCLUSIONS

The mFI-5 is an independent predictor of postoperative complications including life-threatening medical complications, surgical site infections, hospital readmission, and 30-day mortality after primary hip and knee arthroplasty. This clinical tool can be used to identify high-risk surgical patients and guide preoperative counseling to optimize outcomes.

LEVEL OF EVIDENCE

III.