The proper timing of second-stage revision in treating periprosthetic knee infection: reliable indicators and risk factors

Leukocyte scintigraphy has high specificity but low sensitivity in diagnosing persistent periprosthetic joint infection before reimplantation in two-stage revision

INTRODUCTION

Two-stage revision is considered the gold standard treatment in chronic periprosthetic joint infection (PJI) but no specific criteria or examination exist to determine infection eradication before reimplantation. This study aimed to assess the diagnostic performance of leukocyte scintigraphy after the first-stage procedure in two-stage revision for chronic PJI.

MATERIAL AND METHODS

Patients studied with leukocyte scintigraphy after cement spacer insertion for knee PJI from January 2012 to December 2021 were retrospectively included. Infection was diagnosed using the criteria of the 2018 International Consensus Meeting. When 1 or more minor criteria were positive but the score was < 6, patients were considered not infected if there was no recurrence of infection at least 24 months after the second-stage procedure. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were found.

RESULTS

The final cohort included 67 cases in 61 patients (M: F = 32:35; mean age 74 years). There were 43 true negatives, 8 true positives, 12 false negatives, and 4 false positives. The sensitivity and specificity of leukocyte scintigraphy in diagnosing PJI were respectively 40.0% and 91.5%, PPV was 66.7%, NPV was 78.2%, and accuracy was 76.1%. Staphylococcus Epidermidis was the most frequently isolated microorganism (50%).

CONCLUSION

Due to the high costs and the difficulty in its execution, LLS should not be used routinely but it could represent an additional criterion in doubtful cases. In any case, a thorough evaluation of other pre- and intra-operative tests is essential to determine whether reimplantation or spacer renewal is the best course of action. Special consideration should be given to positive LLS, as its results are highly specific and have a low rate of false positives. Conversely, in over half of infected patients, LLS could give false negatives, making negative LLS results less relevant.

Predictors of outcome following two-stage revision total knee arthroplasty

PURPOSE

Two stage revision arthroplasty remains the gold standard for peri-prosthetic joint infections of the knee. However, the functional outcomes of revision surgeries and the factors governing them require further investigation. The purpose of this study was to (a) evaluate impact of early and late stage I surgery and interval between stage I and stage II; (b) understand the impact of infecting organism and resistance; (c) to estimate long term survivorship and causes of failure.

METHODS

A retrospective review of 86 patients, who underwent two stage revision for prosthetic joint infections of the knee, was performed. Time between onset of symptoms to stage I (T1), and T1 to re-implantation (T2), along with microbiological studies, were analysed for their impact on functional outcomes, failure modalities and survivorship.

RESULTS

In this study, the mean KSS-Knee improved from 64.0 ± 10.0 pre-operatively to 76.9 ± 10.4, and 77.2 ± 10.1 at the 5 and 10 year follow up respectively. The KSS-Function improved from 44.4 ± 8.8 pre-operatively to 72.2 ± 9.5 and 79.8 ± 8.1 at 5 and 10 year follow-up respectively. This study also found that T1 and T2 remained critical factors in determining functional outcome and longevity of the implant and a delay in these intervals was a significant predictor of failure. Gram negative, poly-microbial infections and organisms with methicillin and vancomycin resistance demonstrated lower survivorship (p-value, 0.001 at 5, 10 and 12 years). Re-infections occurred in 4 cases while 9 cases failed due to aseptic causes.

CONCLUSION

Two-stage revision arthroplasty produced good functional outcomes when the infection was caused by single sensitive organism that did not exhibit high resistance to antibiotics. Stage I performed within 4 weeks and the subsequent re-implantation procedure undertaken within 6 weeks demonstrated better outcomes.

Review of recent advances in the diagnosis and management of periprosthetic joint infection after total knee arthroplasty part 2: single-stage or two-stage surgical technique?

Periprosthetic joint infection (PJI) after total knee arthroplasty is a complication that affects approximately 2-3% of patients. The management of this issue is complicated and expensive for both the patients and the healthcare system. Multiple management options are available including antibiotic suppressive therapy, surgical management, and salvage procedures. Surgical management is considered a popular option for treating PJI, with multiple available surgical techniques, including single-stage revision arthroplasty and two-stage revision arthroplasty among others. Two-stage revision has been considered the gold standard for treating PJI. This method consists of two surgical procedures with a time interval in between, the first procedure aims to eradicate the infection along with implanting either a static or a mobile spacer, while the second intervention aims to remove the spacer and implant a new prothesis. During the interval period the patient is closely monitored through a handful of laboratory tests and clinical signs that help in assessing the optimal time of undertaking the second stage. However, in recent years, the single-stage method has gained much attention for its comparable outcomes and fewer complications. Contrary to the two-stage method, the single-stage approach consists only of one procedure in which the old infected prosthesis is removed and a new one is implanted. Many articles have compared the two methods over the years but have not agreed on a particular approach to be more potent in eliminating infection and providing better outcomes. Plenty of questions are yet to be answered regarding the two methods, including the superior type of spacer, interim period duration, and single-stage revision inclusion criteria. We herein, aim to address these issues, highlighting recent advances in managing this morbid complication and discussing controversial topics in the staged procedures.

Intermittent alternating magnetic fields diminish metal-associated biofilm in vivo

Prosthetic joint infection (PJI) is a complication of arthroplasty that results in significant morbidity. The presence of biofilm makes treatment difficult, and removal of the prosthesis is frequently required. We have developed a non-invasive approach for biofilm eradication from metal implants using intermittent alternating magnetic fields (iAMF) to generate targeted heating at the implant surface. The goal of this study was to determine whether iAMF demonstrated efficacy in an in vivo implant biofilm infection model. iAMF combined with antibiotics led to enhanced reduction of biofilm on metallic implants in vivo compared to antibiotics or untreated control. iAMF-antibiotic combinations resulted in a > 1 - log further reduction in biofilm burden compared to antibiotics or iAMF alone. This combination effect was seen in both S. aureus and P. aeruginosa and seen with multiple antibiotics used to treat infections with these pathogens. In addition, efficacy was temperature dependent with increasing temperatures resulting in a greater reduction of biofilm. Tissue damage was limited (< 1 mm from implant-tissue interface). This non-invasive approach to eradicating biofilm could serve as a new paradigm in treating PJI.

Interval between two-stage exchanges: what is optimal and how do you know?

BACKGROUND

Two-stage exchange arthroplasty remains the most popular option for the treatment of chronic periprosthetic joint infection (PJI). Determining infection eradication and optimal timing of reimplantation can be challenging. Information to allow for a truly informed evidence-based decision is scarce.

METHODS

We conducted a critical review of available evidence on the presently available tests to help determine timing of reimplantation.

RESULTS

Serology is traditionally used to follow up patients after the first stage. Despite tradition mandates waiting for normal inflammatory markers, there is actually no evidence that they correlate with persistent infection. The role of synovial fluid investigation between stages is also explored. Cultures lack sensitivity and neither differential leukocyte counts nor alternative biomarkers have proven to be accurate in identifying persistent infection with a spacer in situ. We also examined the evidence regarding the optimal time interval between resection and reimplantation and whether there is evidence to support the implementation of a two week "antibiotic holiday" prior to proceeding with reimplantation. Finally, wound healing and other important factors in this setting will be discussed.

CONCLUSION

Currently there are no accurate metrics to aid in the decision on the optimal timing for reimplantation. Decision must therefore rely on the resolution of clinical signs and down trending serological and synovial markers.

Factors Influencing the Clinical Outcomes of Two-Stage Re-Implantation in Patients With Periprosthetic Joint Infection After Total Knee Arthroplasty

Introduction Infection is one of the most distressing complications of total knee arthroplasty (TKA), requiring a long treatment process and may negatively affect patient satisfaction. All surgeons aim to achieve infection-free survival, painless, functional, and stable knee after treatment of periprosthetic joint infection (PJI) with two-stage revision treatment. Many factors play a role in determining clinical outcomes. We aimed to evaluate the factors influencing the clinical outcomes of patients undergoing two-stage revision knee arthroplasty for PJI. Methods Forty-nine patients were retrospectively evaluated. Forty-four patients met the inclusion criteria. Spacer types, growth rates in culture, types and amount of antibiotics added to the cement, and intervals between stages were evaluated. Pre- and post-treatment infection parameters, changes in the range of motion (ROM), clinical and functional (C&F) Knee Society Score (KSS) results, and complications were also studied. Results After a mean follow-up of 48.8 ± 16.5 months, re-infection was detected in five out of 44 patients (10.4%). No significant difference was noted regarding C&F KSS when comparing time intervals between the two stages, whether they were shorter or longer than 10 weeks. However, better ROM results were obtained in patients with less than 10 weeks between stages. The relationship between spacer type, ROM, and C&F KSS was not found to be significant. Particularly, the addition of 4g of teicoplanin to the cement shortened the time between the two stages. Conclusion C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels can be considered safe parameters for diagnosis, reimplantation timing, and follow-up. The use of dynamic spacers or reimplantation performed within 10 weeks after the first stage is associated with better ROM outcomes. Additionally, the addition of teicoplanin to the cement shortened the duration of antibiotic therapy.

Utility of D-dimer in total joint arthroplasty

As the number of patients receiving total joint replacements continues to rise, considerable attention has been directed towards the early detection and prevention of postoperative complications. While D-dimer has long been studied as a diagnostic tool in venous thromboembolism (VTE), this assay has recently received considerable attention in the diagnosis of periprosthetic joint infection (PJI). D-dimer values are substantially elevated in the acute postoperative period after total joint arthroplasty, with levels often exceeding the standard institutional cutoff for VTE (500 µg/L). The utility of D-dimer in detecting VTE after total joint replacement is currently limited, and more research to assess its value in the setting of contemporary prophylaxis protocols is warranted. Recent literature supports D-dimer as a good to excellent biomarker for the diagnosis of chronic PJI, especially when using serum sample technique. Providers should exercise caution when interpreting D-dimer levels in patients with inflammatory and hypercoagulability disorders, as the diagnostic value is decreased. The updated 2018 Musculoskeletal Infection Society criteria, which includes D-dimer levels > 860 µg/L as a minor criterion, may be the most accurate for diagnosing chronic PJI to date. Larger prospective trials with transparent lab testing protocols are needed to establish best assay practices and optimal cutoff values for D-dimer in the diagnosis of PJI. This review summarizes the most current literature on the value of D-dimer in total joint arthroplasty and elucidates areas for future progress.

Comparable clinical outcomes of culture-negative and culture-positive periprosthetic joint infections: a systematic review and meta-analysis

PURPOSE

The aim of this study was to compare the clinical outcomes of culture-negative periprosthetic joint infection (CN PJI) with those of culture-positive periprosthetic joint infection (CP PJI).

METHODS

Data were obtained from Embase, Web of Science and EBSCO for all available studies comparing the clinical outcomes of CN PJI with those of CP PJI. The quality of the studies was scored using the Newcastle-Ottawa scale (NOS). Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess clinical outcomes. Subgroup analyses were performed to explain heterogeneity among the included studies. Publication bias was estimated using Begg's funnel plot. Sensitivity analysis was performed to test the stability of pooled results.

RESULTS

Thirty studies with 1630 (38.7%) CN PJI and 2577 (61.3%) CP PJI were included in this meta-analysis. The pooled results of the included studies showed that overall failure rate in CN PJI group (19.0%, 309/1630) was significantly lower than that in CP PJI group (23.4%, 604/2577) (OR 0.63, 95% CI 0.47-0.84, P = 0.002). We performed the subgroup analysis based on the surgical strategies, the pooled results of nine studies for patients undergoing debridement, antibiotics and implant retention (DAIR) revealed that failure rate in CN PJI group (22.2%, 53/239) was significantly lower than that in CP PJI group (29.3%, 227/775) (OR 0.62, 95% CI 0.43-0.90, P = 0.01), the pooled results of four studies for patients undergoing one-stage revision revealed that failure rate between CN PJI group (11.5%, 11/96) and CP PJI group (7.6%, 27/355) had no significant difference (OR 1.57, 95% CI 0.75-3.26, P = 0.23), and the pooled results of 19 studies for patients undergoing two-stage revision revealed that failure rate in CN PJI group (16.1%, 171/1062) was significantly lower than that in CP PJI group (20.4%, 206/1010) (OR 0.52, 95% CI 0.34-0.79, P = 0.002).

CONCLUSIONS

CN PJI group had similar or better survival rate when compared with CP PJI group for patients who underwent DAIR, one-stage or two-stage revision. Negative culture was not a worse prognostic factor for PJI.

Utility of Diagnostic Tests Before Reimplantation in Patients Undergoing 2-Stage Revision Total Joint Arthroplasty: A Systematic Review and Meta-analysis

INTRODUCTION

Periprosthetic joint infection (PJI) is a devastating complication after total joint arthroplasty (TJA), with treatment failure occurring in 12% to 28% after 2-stage revision. It is vital to identify diagnostic tools indicative of persistent infection or treatment failure after 2-stage revision for PJI.

METHODS

The Cochrane Library, PubMed (MEDLINE), and EMBASE were searched for randomized controlled trials and comparative observational studies published before October 3, 2021, which evaluated the utility of serum/plasma biomarkers (erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], interleukin-6 [IL-6], fibrinogen, D-dimer), synovial biomarkers (white blood cell [WBC] count, neutrophil percentage [PMN %], alpha-defensin [AD], leukocyte esterase [LE]), tissue frozen section, tissue culture, synovial fluid culture, or sonicated spacer fluid culture indicative of persistent infection before the second stage of 2-stage revision for PJI or treatment failure after 2-stage revision for PJI.

RESULTS

A total of 47 studies including 6,605 diagnostic tests among 3,781 2-stage revisions for PJI were analyzed. Among those cases, 723 (19.1%) experienced persistent infection or treatment failure. Synovial LE (sensitivity 0.25 [0.10-0.47], specificity 0.99 [0.93-1.00], positive likelihood ratio 14.0 [1.45-135.58]) and serum IL-6 (sensitivity 0.52 [0.33-0.70], specificity 0.92 [0.85-0.96], positive likelihood ratio 7.90 [0.86-72.61]) had the highest diagnostic accuracy. However, no biomarker was associated with a clinically useful negative likelihood ratio. In subgroup analysis, synovial PMN %, synovial fluid culture, serum ESR, and serum CRP had limited utility for detecting persistent infection before reimplantation (positive likelihood ratios ranging 2.33-3.74; negative likelihood ratios ranging 0.31-0.9) and no utility for predicting failure after the second stage of 2-stage revision.

CONCLUSIONS

Synovial WBC count, synovial PMN %, synovial fluid culture, serum ESR, and serum CRP have modest sensitivity and specificity for predicting persistent infection during the second stage of 2-stage revision, suggesting some combination of these diagnostic tests might be useful before reimplantation. No biomarker or culture accurately predicted treatment failure after reimplantation.

LEVEL OF EVIDENCE

Level III. See Instructions for Authors for a complete description of levels of evidence.

One- or two-stage reimplantation for infected total knee prosthesis?

A prosthetic joint infection (PJI) is possibly the most significant potential complication of total knee arthroplasty (TKA) and is associated with substantial morbidity and socioeconomic burden. It is a devastating complication for both the patient and the surgeon alike. A two-stage revision approach for infected TKA has been the standard for surgical management; however, there is growing interest in single-stage revision surgery due to fewer procedures, reduced inpatient hospital stay and reduced costs to healthcare systems. A one-stage exchange is indicated when there is no sign of systemic sepsis and in cases where a microorganism has been isolated. It involves removal of the old prosthesis, debridement of all infected tissue, a copious washout and re-draping, and finally, re-implantation of a new prosthesis. The two-stage approach involves the use of an antibiotic spacer before the second stage is carried out. The length of time between the stages is discussed. Patients with a PJI should be managed by a multidisciplinary team. We recommend these patients are managed in specialist arthroplasty centres by high volume revision arthroplasty specialists.

Detection of inguinal lymph nodes is promising for the diagnosis of periprosthetic joint infection

Background

Localized inguinal lymphadenopathy often represents lower extremity pathogen infection, while normalized lymphadenopathy is associated with infection regression. We hypothesized that inguinal lymph nodes (LNs) were enlarged in Periprosthetic Joint Infection (PJI) patients and that normalized inguinal LNs would be a promising way to determine the timing of reimplantation.

Methods

We prospectively enrolled 176 patients undergoing primary and revision hip or knee arthroplasty. All patients underwent ultrasound examination of inguinal LNs preoperatively. The diagnostic value of inguinal LNs in PJI was evaluated by the receiver operating characteristic (ROC) curve.

Results

The median level of inguinal LNs was 26mm in the revision for PJI group compared with 12 mm in the aseptic revision group (p< 0.0001). The size of the inguinal LNs well distinguishes PJI from aseptic failure (AUC= 0.978) compare with ESR (AUC= 0.707) and CRP (AUC= 0.760). A size of 19mm was determined as the optimal threshold value of the inguinal LNs for the diagnosis of PJI, with a sensitivity of 92% and specificity of 96%.

Conclusion

Ultrasonic analysis of inguinal LNs is a valuable piece of evidence for the diagnosis of PJI and evaluation of persistent infection.

Diagnostic Value of C-Reactive Protein and Serum White Blood Cell Count during Septic Two-Stage Revision of Total Knee Arthroplasties

AIMS AND METHODS

In septic two-stage revision arthroplasty, the timing of reimplantation is crucial for therapeutic success. Recent studies have shown that singular values of C-reactive protein (CRP) and white blood cell count (WBC count) display weak diagnostic value in indicating whether periprosthetic joint infection (PJI) is controlled or not during two-stage revision surgery of knee arthroplasty. Therefore, in addition to the values of CRP and WBC, the course of CRP and WBC counts were compared between groups with and without later reinfection in 95 patients with two-stage revision (TSR) of infected total knee arthroplasties (TKA). Of these patients, 16 had a reinfection (16.84%).

RESULTS

CRP values decreased significantly after the first stage of TSR in both the reinfection and no-reinfection groups. WBC count values decreased significantly in the no-reinfection group. Decrease in WBC count was not significant in the reinfection group. No significant difference could be found in either the CRP values or the WBC counts at the first stage of TSR, the second stage of TSR, or their difference between stages when comparing groups with and without reinfection. Area under the curve (AUC) values ranging between 0.631 and 0.435 showed poor diagnostic value for the calculated parameters. The courses of CRP over 14 days after the first stage of both groups were similar with near identical AUC.

CONCLUSIONS

CRP and WBC count as well as their course over 14 days postoperatively are not suitable for defining whether a PJI of the knee is under control or not.

Risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for the treatment of periprosthetic joint infection

BACKGROUND

Prosthesis removal and antibiotic bone cement spacer implantation is a very important link in two-stage revision of periprosthetic joint infection (PJI) after artificial joint replacement, which is key to the smooth progress of second-stage revision surgery. There are few reports on the risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for PJI. This study aimed to investigate the risk factors of reinfection after prosthesis removal and antibiotic bone cement spacer implantation for the treatment of PJI.

METHODS

Clinical data of 40 patients who underwent prosthesis removal and antibiotic bone cement spacer implantation for PJI after arthroplasty in our hospital from January 2013 to July 2019 were retrospectively analyzed. During the follow-up period of at least 2 years, 21 patients underwent complete two-stage revision after the removal of the antibiotic bone cement spacer, and 19 patients did not receive a new prosthesis due to other factors, such as reinfection or the patient's wishes, record the infection control of patients during the treatment. Reinfection after prosthesis removal and antibiotic bone cement spacer implantation was defined as failure of effective control of infection, symptoms of reinfection, requires increased antibiotic therapy or reoperation. Multivariate Cox proportional hazards model was used to analyze the risk factors associated with reinfection after prosthesis removal and antibiotic bone cement spacer implantation.

RESULTS

Of the 40 patients, nine (22.5%) developed reinfection after prosthesis removal and antibiotic bone cement spacer implantation with a mean follow-up duration of 31 months, and multivariate analysis revealed that history of prior revision surgery (hazard ratio [HR] = 6.317, confidence interval [CI]: 1.495-26.700; p = 0.012) and presence of sinus tract before treatment (HR = 5.117, 95% CI: 1.199-21.828; p = 0.027) were independent risk factors for reinfection after prosthesis removal and antibiotic bone cement spacer implantation.

CONCLUSION

History of prior revision surgery and presence of sinus tract are two independent risk factors for reinfection in patients with PJI treated with prosthesis removal and antibiotic bone cement spacer implantation.

Against the Norm: Do Not Rely on Serum C-Reactive Protein and White Blood Cell Count Only When Assessing Eradication of Periprosthetic Joint Infection

Introduction: Periprosthetic joint infections (PJI) following primary arthroplasty continue to be a serious complication, despite advances in diagnostics and treatment. Two-stage revision arthroplasty has been commonly used as the gold standard for the treatment of PJI. However, much discussion persists regarding the interim of the two-stage procedure and the optimal timing of reimplantation. Serology markers have been proposed as defining parameters for a successful reimplantation. The objective of this matched-pair analysis was to assess the role of serum C-reactive protein (CRP) and white blood cell count (WBC) in determining infection eradication and proper timing of reimplantation. We investigated the delta (∆) change in CRP and WBC values prior to both stages of two-stage revision arthroplasty as a useful marker of infection eradication. Methods: We analyzed 39 patients and 39 controls, matched by propensity score matching (BMI, age, ASA-classification), with a minimum follow-up of 24 months and treated with a two-stage revision THA or TKA in our institution. Data of serum CRP and WBC values were gathered at two selected time points: prior to the explantation of the implant (preexplantation) and following the completion of antibiotic treatment regimen, both systemic and with a drug-eluting cement spacer (prereimplantation). Patient records were reviewed electronically for preexisting comorbidities, overall health status, synovial fluid cultures, inflammatory serologies, revision surgeries, and recurrent or persistent infection based on the modified Musculoskeletal Infection Society criteria. Patient demographics, ∆CRP, ∆WBC, and time interval to reimplantation were statistically analyzed using receiver operator curves (ROC), Pearson’s correlation coefficient, Levene’s test, and Student’s t-test. Results: Infection-free patients exhibited higher mean CRP and WBC than did patients who were reinfected at both time points. When comparing preexplantation with prereimplantation values, the median ∆CRP was 9.48 mg/L (interquartile range (IQR) 2.3−36.6 mg/L) for patients who did not develop a reinfection versus 2.74 mg/L (IQR 1.4−14.2 mg/L) for patients who developed reinfection (p = 0.069). The median ∆WBC was 1.5 × 109/L (IQR 0.6−4.0 × 109/L) for patients who remained infection-free versus 1.2 × 109/L (IQR 0.8−2.2 109/L) for patients who developed reinfection (p = 0.072). Analysis of areas under the curve (AUC) using ROC demonstrated poor prediction of persistent infection by ∆CRP (AUC = 0.654) and ∆WBC (AUC = 0.573). Although a highly significant correlation was found between the interim interval and infection persistence (r = 0.655, p < 0.01), analysis using ROC failed to result in a specific threshold time to reimplantation above which patients are at significantly higher risk for reinfection (AUC = 0.507). Conclusion: No association could be determined between the delta change in serum CRP and WBC before and after two-stage revision arthroplasty for PJI and reinfection risk. Even though inflammatory serologies demonstrate a downtrending pattern prior to reimplantation, the role of CRP and WBC in determining the optimal timing of reimplantation seems to be dispensable. Planning a second-stage reimplantation requires assessing multiple variables rather than relying on specific numeric changes in these inflammatory marker values.

Diagnostic Value of CRP and Serum WBC Count during Septic Two-Stage Revision of Total Hip Arthroplasties

The diagnostic value of C-reactive protein (CRP) and the serum white blood cell (WBC) count is still barely defined for decision making during septic two-stage revision surgery of hip arthroplasty. We, therefore, compared these values between stages as well as between the groups without and with reinfection in 117 patients. A total of 106 patients were reinfection-free (91%). The median follow-up was 51 months. With a ΔCRP of −10 mg/L and a ΔWBC count of −1000/µL, a significant decrease between stages (p = 0.001) could be observed. When comparing the CRP and WBC count values between groups, however, no significant difference was found at stage one, stage two and even the difference between these two time points (reinfection-free ΔCRP of −11 mg/L and ΔWBC count of −1000/µL vs. reinfection ΔCRP of −5 mg/L (p = 0.131) and ΔWBC count of −1100/µL) (p = 0.424). The diagnostic value was poor for the calculated parameters (area under the curve (AUC) 0.5–0.6). The courses of the mean CRP values of both groups were similar. We conclude that the CRP and WBC count are not helpful to guide the decision making in individual cases.

Paradoxical Behavior of Plasma d-Dimer From Explantation to Reimplantation in a Two-Stage Revision for Periprosthetic Joint Infection

BACKGROUND

The variation of plasma d-dimer, an inflammatory marker, from pre-explantation to pre-reimplantation in two-stage revision remains unclear. Our objective was to evaluate delta-changes (Δ) in d-dimer, erythrocyte sedimentation rate (ESR), and C-reactive-protein (CRP), to ascertain whether these delta-changes are associated with the outcome of reimplantation. We hypothesized a decrease in d-dimer before reimplantation.

METHODS

A retrospective review was performed on a consecutive series of 95 two-stage revisions indicated for periprosthetic joint infection. Surgeries were performed by 3 surgeons at a single institution (2018-2020). The minimum follow-up was 1 year. The inclusion criteria comprised availability of d-dimer results at pre-explantation and pre-reimplantation. As a result, only 30 reimplantations were included. Success of reimplantation was defined by Musculoskeletal Infection Society outcome reporting tool: Tier 1/Tier 2 vs Tier 3/Tier 4. Nonparametric tests and Mann-Whitney U-tests were conducted to compare Δd-dimer% (pre-explantation value - pre-reimplantation value/pre-explantation value × 100). The bootstrapped receiver operating characteristic curve analyses with 2,000 replicates of 30 cases were conducted.

RESULTS

The median time between explantation and reimplantation was 86 days (interquartile range [IQR] = 77.7-138.5 days). Overall, a paradoxical median percent increase (Δd-Dimer% [INCREMENT] = 12.6%) in d-dimer was found from pre-explantation to pre-reimplantation (IQR = -28.06% to 77.3%). However, there was a percentage decrease in ESR (ΔESR% [DECREMENT] = -40%; IQR = -70.52% to 3.85%) and CRP (ΔCRP% [DECREMENT] = -75%; IQR = -87.43% to -61.34%). The changes in all these markers were not different between Musculoskeletal Infection Society Tier 1/2 and 3/4 outcomes (Δd-Dimer%, P = .146; ΔESR%, P = .946; ΔCRP%, P = .463). With area under curve of 0.676, Δd-dimer% (INCREMENT) appeared to be performing best in diagnosing infection control, which was nonexplanatory.

CONCLUSION

Plasma d-dimer paradoxically increases before reimplantation while other inflammatory markers (ESR/CRP) decrease, emphasizing that surgeons shall adopt caution using d-dimer to make clinical decisions.

Does Time to Reimplantation After Explant for Prosthetic Joint Infection Influence the Likelihood of Successful Outcomes at 2 Years?

BACKGROUND

Consensus recommendations are lacking regarding appropriate timing of reimplantation following 2-stage resection arthroplasty for prosthetic joint infections (PJIs). We investigated whether the time from resection arthroplasty to reimplantation was associated with treatment outcome at 2 years.

METHODS

Retrospective cohort review was conducted for 101 patients undergoing resection arthroplasty with an antibiotic spacer for PJI at a single tertiary academic referral institution. Time from explantation and spacer placement to reimplantation was categorized into 3 groups: <12, 12-18, and >18 weeks. Baseline patient and treatment course characteristics across these groups were obtained. Multivariate binary logistic regression was used to characterize association between treatment failure and time to reimplantation, controlling for American Society of Anesthesiologists (ASA) score and prior revision surgery.

RESULTS

Time to reimplantation (TTR) >18 weeks demonstrated statistically significant increased odds of treatment failure, after controlling for ASA score and prior revision surgery (odds ratio 7.00, confidence interval 2.14-25.42, P = .002). After excluding patients requiring second spacer or Girdlestone prior to replant, this increased odds of failure remained (odds ratio 4.12, confidence interval 1.18-15.37, P = .029). TTR groups were similar with respect to demographics, except for ASA (2.96 for time to reimplantation >18 weeks vs 2.55 for time to reimplantation <12 weeks; P = .011). Patients with TTR >18 weeks were more likely to have an unplanned readmission during the spacer period (48%, 19%, and 6% for time to reimplantation >18, 12-18, and 0-12 weeks, respectively; P < .002).

CONCLUSION

Although decision regarding TTR is largely patient specific, surgeons should be aware that TTR >18 weeks may be associated with higher rates of treatment failure at 2 years.

Periprosthetic Knee Infection - Part 2: Treatment

Several treatment modalities are proposed for periprosthetic infections, with variable success rates. However, efficacy is related to the appropriate selection of cases for each type of treatment. Debridement with implant retention is indicated in acute infections with fixed implant, and its success depends on the type of infection, comorbidities of the host, and virulence of the etiological agent. One- or two-stage revision is required in cases in which biofilm is forming, or of implant loosening. The choice between performing the review in one or two stages depends on factors such as etiological agent identification, pathogen virulence, local and systemic host factors. Rescue procedures such as arthrodesis, amputation, resection arthroplasty or even antibiotic suppression are reserved for cases in which the infection has not been eradicated.

Thromboelastography parameters in diagnosing periprosthetic joint infection and predicting reimplantation timing

BACKGROUND

Coagulation-related biomarkers are drawing new attention in the diagnosis of periprosthetic joint infection (PJI). The thromboelastography (TEG) assay provides a comprehensive assessment of blood coagulation; therefore, it could be a promising test for PJI. This study aims to assess the value of TEG in diagnosing PJI and to determine the clinical significance of TEG in analysing reimplantation timing for second-stage revision.

METHODS

From October 2017 to September 2020, 62 patients who underwent revision arthroplasty were prospectively included. PJI was defined by the 2011 Musculoskeletal Infection Society criteria, in which 23 patients were diagnosed with PJI (Group A), and the remaining 39 patients were included as having aseptic loosening (Group B). In group A, 17 patients completed a two-stage revision in our centre. C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), D-dimer, and TEG parameters (clotting time, α-angle, MA [maximum amplitude], amplitude at 30 min, and thrombodynamic potential index) were measured preoperatively in all included patients. In addition, receiver operating characteristic curves were used to evaluate the diagnostic value of these biomarkers.

RESULTS

ESR (area under curve [AUC], 0.953; sensitivity, 81.82; specificity, 94.87) performed best for PJI diagnosis, followed by MA (AUC, 0.895; sensitivity, 82.61; specificity, 97.44) and CRP (AUC, 0.893; sensitivity, 82.61; specificity, 94.74). When these biomarkers were combined in pairs, the diagnostic value improved compared with any individual biomarker. The overall success rate of the two-stage revision was 100%. Furthermore, ESR and MA were valuable in determining the time of reimplantation, and their values all decreased below the cut-off values before reimplantation.

CONCLUSION

TEG could be a promising test in assisting PJI diagnosis, and a useful tool in judging the proper timing of reimplantation.

Partial two-stage exchange: an alternative method for infected total hip arthroplasty

Background

Total two-stage exchange is commonly used in clinical practice as a treatment for infected total hip arthroplasty (THA); however, this approach involves considerable limitations, including significant bone loss and severe trauma. This retrospective cohort study was conducted to evaluate clinical outcomes following the use of partial two-stage exchange (PTE) for infected THA.

Methods

We performed a retrospective analysis of 28 patients with infected THA who were treated by PTE between September 2000 and June 2019. Eligibility for PTE was limited to patients with a well-fixed femoral stem prosthesis. In the first stage of the operation, the femoral stem prosthesis was preserved; subsequently, the acetabular prosthesis, liner, and head were replaced with an antibiotic-loaded spacer. The new prosthesis was then implanted into patients and monitored for at least 3 months to ensure freedom from infection.

Results

Patients were followed for an average of 4 years (range, 2–11 years), with an overall success rate of 85.7% (24/28). The mean Harris hip score at the final follow-up was 76.2 ± 11.7 points.

Conclusions

The findings of this study suggest that PTE could be an acceptable option for a subset of patients with infected THA, offering a satisfactory infection control rate and clinical outcomes comparable to those of total two-stage exchange, but with less harm.

Emergence of Antibiotic Resistance Across Two-Stage Revision for Periprosthetic Joint Infection

BACKGROUND

The current preferred treatment for chronic hip and knee periprosthetic joint infection (PJI) involves both surgical intervention and antibiotic treatment as part of a two-stage revision. The purpose of this study is to determine how often patients who underwent a two-stage revision for chronic PJI developed a subsequent antibiotic-resistant infection.

METHODS

We retrospectively reviewed the clinical records of 142 patients who underwent a two-stage revision for a chronic culture-positive PJI from January 2014 to May 2019. Demographic data and risk factors for PJI were identified. Resistance was defined in accordance with microbiology laboratory report and minimum inhibitory concentration. Statistical analysis consisted of descriptive statistics and univariate analysis.

RESULTS

Only 10 of the 142 patients (7.04%) demonstrated emergence of resistance to antibiotics across their two-stage revision. At reimplantation, 25 (17.6%) patients had positive cultures. Of these, 16 patients presented with a novel organism and 9 patients had positive culture for the same organism as the initial infection. During the entire course of the two-stage revision, including spacer exchanges and irrigation and debridement procedures, 15 (10.56%) patients demonstrated persistent infections, whereas 25 (17.6%) patients presented with novel infections. 26 (18.3%) patients had reinfection of the same joint within one year.

CONCLUSION

In the given cohort, there does not appear to be a major emergence of antibiotic resistant organisms in patients undergoing two-stage exchange arthroplasty and antibiotic treatment.

Plasma D-dimer Does Not Anticipate the Fate of Reimplantation in Two-stage Exchange Arthroplasty for Periprosthetic Joint Infection: A Preliminary Investigation

BACKGROUND

Inflammatory markers such as the erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels have always been a part of the diagnostic criteria for periprosthetic joint infection (PJI), but they perform poorly anticipating the outcome of reimplantation. D-dimer has been reported in a small series as a potential marker to measure infection control after single-stage revisions to treat PJI. Nonetheless, its use to confirm infection control and decide the proper timing of reimplantation remains uncertain.

QUESTIONS/PURPOSES

(1) What is the best diagnostic threshold and accuracy values for plasma D-dimer levels compared with other inflammatory markers (ESR and CRP) or what varying combinations of these tests are associated with persistent infection after reimplantation? (2) Do D-dimer values above this threshold, ESR, CRP, and varying test combinations at the time of reimplantation indicate an increased risk of subsequent persistent infection after reimplantation?

METHODS

We retrospectively studied the electronic medical records of all 53 patients who had two-stage revisions for PJI and who underwent plasma D-dimer testing before reimplantation at one of two academic institutions from November 22, 2017 to December 5, 2020. During that period, all patients undergoing two-stage revisions also had a D-dimer test drawn. The minimum follow-up duration was 1 year. We are reporting at this early interval (rather than the more typical 2-year time point) because of the poorer-than-expected performance of this diagnostic test. Of these 53 patients, 17% (9) were lost to follow-up before 1 year and could not be analyzed; the remaining 44 patients (17 hips and 27 knees) were studied here. The mean follow-up was 503 ± 135 days. Absence or persistence of infection after reimplantation were defined according to the Delphi criteria. The conditions included in these criteria were: (1) control of infection, as characterized by a healed wound without fistula, drainage, or pain; (2) no subsequent surgical intervention owing to infection after reimplantation; and (3) no occurrence of PJI-related mortality. The absence of any of the aforementioned conditions until the final follow-up examination was deemed a persistent infection after reimplantation. Baseline patient characteristics were not different between patients with persistent infection (n = 10) and those with absence of it after reimplantation (n = 34) as per the Delphi criteria. Baseline patient characteristics evaluated were age, gender, self-reported race (white/Black/other) or ethnicity (nonHispanic/Hispanic), BMI, American Society of Anesthesiologists (ASA) status, smoking status(smoker/nonsmoker), and joint type (hip/knee). The optimal D-dimer threshold to differentiate between persistence of infection or not after reimplantation was calculated using the Youden index. A receiver operating characteristic curve analysis was performed to test the accuracy of D-dimer, ESR, CRP, and their combinations to establish associations, if any, with persistent infection after reimplantation. A Kaplan-Meier survival analysis (free of infection after reimplantation) with a log-rank test was performed to investigate if D-dimer, ESR, and CRP were associated with absence of infection after reimplantation. Survival or being free of infection after reimplantation was determined as per Delphi criteria. Alpha was set at p < 0.05.

RESULTS

In the receiver operating characteristic curve analysis, with an area under the curve of 0.62, D-dimer showed low accuracy and did not anticipate persistent infection after reimplantation. The optimal D-dimer threshold differentiating between persistence of infection or not after reimplantation was 3070 ng/mL. When using this threshold, D-dimer demonstrated a sensitivity of 90% (95% CI 55.5% to 99.7%) and negative predictive value of 94% (95% CI 70.7% to 99.1%), but low specificity (47% [95% CI 29.8% to 64.9%]) and positive predictive value (33% [95% CI 25.5% to 42.2%]). Although D-dimer showed the highest sensitivity, the combination of D-dimer with ESR and CRP showed the highest specificity (91% [95% CI 75.6% to 98%]) defining the persistence of infection after reimplantation. Based on plasma D-dimer levels, with the numbers available, there was no difference in survival free from infection after reimplantation (Kaplan-Meier survivorship free from infection at minimum 1 year in patients with D-dimer below 3070 ng/mL versus survivorship free from infection with D-dimer above 3070 ng/mL: 749 days [95% CI 665 to 833 days] versus 615 days [95% CI 471 to 759 days]; p = 0.052). Likewise, there were no associations between high ESR and CRP levels and persistent infection after reimplantation, but the number of events was very small, and insufficient power is a concern with this analysis.

CONCLUSION

In this preliminary series, with the numbers available, D-dimer alone had poor accuracy and was not associated with survival free from infection after reimplantation in patients who underwent two-stage exchange arthroplasty. D-dimer alone might be used to establish that PJI is unlikely, and the combination of D-dimer, ESR, and CRP should be considered to confirm PJI diagnosis in the setting of reimplantation.Level of Evidence Level IV, diagnostic study.

Positive frozen section during reimplantation increases the risk of treatment failure in two-stage exchange arthroplasty even in patients with normal ESR and CRP

AIMS

It can be extremely challenging to determine whether to perform reimplantation in patients who have contradictory serum inflammatory markers and frozen section results. We investigated whether patients with a positive frozen section at reimplantation were at a higher risk of reinfection despite normal ESR and CRP.

METHODS

We retrospectively reviewed 163 consecutive patients with periprosthetic joint infections (PJIs) who had normal ESR and CRP results pre-reimplantation in our hospital from 2014 to 2018. Of these patients, 26 had positive frozen sections at reimplantation. The minimum follow-up time was two years unless reinfection occurred within this period. Univariable and multivariable logistic regression analyses were performed to identify the association between positive frozen sections and treatment failure.

RESULTS

Treatment failure occurred in eight (30.77%) of the 26 PJI patients with positive frozen sections at reimplantation, compared with 13 (9.49%) of 137 patients with negative results. In the multivariate analysis, positive frozen section increased the risk of failure (odds ratio 4.70; 95% confidence interval (CI) 1.64 to 13.45). The mean number of months to reinfection was lower in the positive frozen section group than in the control group (p = 0.041). While there were nine (34.62%) patients with positive frozen section and 25 (18.25%) patients with negative frozen section who had prolonged antibiotic use (p = 0.042), the mean duration of antibiotic use was comparable in two groups. Synovial white blood cell count (p = 0.137) and polymorphonuclear leucocyte percentage (p = 0.454) were not associated with treatment failure in logistic regression model.

CONCLUSION

Positive frozen section at reimplantation was independently associated with subsequent failure and earlier reinfection, despite normal ESR and CRP levels pre-reimplantation. Surgeons should be aware of the risk of treatment failure in patients with positive frozen sections and carefully consider benefits of reimplantation. Cite this article: Bone Joint J 2021;103-B(5):916-922.

The 2018 New Definition of Periprosthetic Joint Infection is Valuable for Diagnosis of Persistent Infection at Reimplantation in Patients without Synovial Fluid

BACKGROUND

Diagnosis of persistent infection at reimplantation of 2-stage exchange revision is a challenging problem. The aim of our study is to evaluate the performance of the 2018 new definition and Musculoskeletal Infection Society (MSIS) criteria in determining the persistent infection at reimplantation in patients without synovial fluid.

METHODS

We retrospectively reviewed 150 patients who underwent 2-stage exchange revision from 2014 to 2018. Two models were used to define persistent infection-model 1: identical major criteria of the MSIS criteria and new definition and model 2: identical major criteria of 2 criteria and/or subsequent infection after reimplantation. The predictive accuracy of the new definition and MSIS criteria was compared by using receiver operating characteristic curves.

RESULTS

The receiver operating characteristic curves showed that the new definition had good performance in determining the persistent infection, with the area under the curve (AUC) of 0.871 in model 1 and 0.835 in model 2. The optimal threshold for aggregate scores in new definition was 4. The MSIS criteria had limited diagnostic value in both model 1 (AUC = 0.708) and model 2 (AUC = 0.664). In model 1, the sensitivity and specificity were 86.96% and 84.25% in new definition, and 47.83% and 93.70% in MSIS criteria in patients without synovial fluid. In model 2, the sensitivity and specificity were 78.57% and 85.25% in new definition, and 39.29% and 93.44% in MSIS criteria.

CONCLUSION

The 2018 new definition of PJI is valuable in the diagnosis of persistent infection, which can improve diagnostic accuracy compared with the MSIS criteria in patients without synovial fluid.

Changes in serum markers failed to predict persistent infection after two-stage exchange arthroplasty

BACKGROUND

The proper timing of reimplantation is importation to treatment success in the two-stage exchange revision. The 2018 International Consensus Meeting suggested that a variation trend toward normalization in serum markers was useful for determining the proper timing of reimplantation. However, the opposite results were found by previous studies, and the normalization of serum markers was reported to fail to predict infection control. We investigated whether value changes and percent changes in four common serum markers (erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), interleukin-6 (IL-6), and fibrinogen) can predict persistent infection.

METHODS

A retrospective review of 141 patients treated with the two-stage revision from 2014 to 2018 was conducted. The variation trend in serum indicators was evaluated by the percent changes (using values of serum markers pre-reimplantation divided by values pre-resection) and value changes (using values of serum markers pre-resection minus values pre-reimplantation). Treatment success was defined according to the Delphi-based consensus criteria with a minimum follow-up of 1 year, and the receiver operator characteristic (ROC) was used to examine the usefulness of changes in serum markers.

RESULTS

Twenty-two patients (15.60%) were persistently infected. No significant difference was found in either the value change or percent change in serum markers between reinfection and non-reinfection patients. When predicting persistent infection, the area under the curves (AUC) demonstrated that both percent changes and value changes in serum markers were poor indicators. The AUC of value changes was 0.533 for the CRP, 0.504 for the IL-6, 0.508 for the ESR, and 0.586 for fibrinogen when predicted persistent PJI. In addition, the AUC indicated that percent changes in the CRP (0.464), the IL-6 (0.534), the ESR (0.527), and fibrinogen (0.586) were all poor markers.

CONCLUSIONS

We have shown that both value changes and percent changes in serum markers were not sufficiently rigorous to aid in persistent infection diagnosis. The proper timing of reimplantation must, therefore, take into account various clinical tests rather than the downward trend of serum markers only.

The Effect of Time Spent with a Dynamic Spacer on Clinical and Functional Outcomes in Two-Stage Revision Knee Arthroplasty

INTRODUCTION

The present study aimed to evaluate the effect of a longer interval between the first and second stages of infected total knee arthroplasty (TKA) revision on the clinical and functional outcome.

METHODS

This study included a total of 56 patients who underwent two-stage revision TKA with a dynamic spacer with a minimum of 2 years of follow-up. Patients were categorized into two groups according to time with the spacer: < 3 months (Group 1, 31 patients) or > 3 months (Group 2, 25 patients). Clinical outcome and quality of life were assessed by knee range of motion (ROM), Knee Society Score for Knee (KSS-K), Knee Society Score for Function (KSS-F) and Short Form 36 (SF-36).

RESULTS

The mean follow-up period was 48 ± 19.1 months (range, 24-84 months). The KSS-K, KSS-F, and ROM values were significantly higher in Group 1 than in Group 2 (p < 0.05). The SF-36 scores for general health, physical function, and bodily pain were significantly higher in Group 1 (p < 0.05). Re-infection occurred in 10 patients (17.8%). Time with spacer was not associated with re-infection development (Group 1, n = 6, 19% vs. Group 2, n = 4, 16%; p > 0.05).

CONCLUSION

Increased duration with a spacer is associated with poorer clinical and functional outcomes as well as higher treatment costs in two-stage revision knee arthroplasty. Surgeons can attempt to reduce the time patients spend in a spacer to obtain better postoperative functional outcomes, as well as a better quality of life.

LEVEL OF EVIDENCE

3.

Partial 2-Stage Exchange for Infected Total Hip Arthroplasty: An Updated Report

BACKGROUND

Management of an infected total hip arthroplasty (THA) is challenging. The eradication of infection as well as complications of component removal must all be considered. This study is an update on previous reports of treating periprosthetic infection of the hip with a partial 2-stage exchange with retention of the femoral component.

METHODS

A retrospective review of our practice's arthroplasty registry from 2000 to 2018 revealed 41 hips with 2-year minimum follow-up that were treated with a 2-stage partial exchange for an infected THA. All first-stage procedures allowed an articulating construct with 1 of 3 variations: cemented constrained liner (13 hips), StageOne Hip Cement Spacer Mold (14 hips), or an antibiotic polymethylmethacrylate head molded from a bulb syringe (14 hips). Of 41 cases, 34 were culture positive, with 3 cases having methicillin-resistant Staphylococcus.

RESULTS

Mean follow-up was 5.5 years (range, 1.5-18.5 years). The second-stage reimplantation was accomplished in 39 of the 41 hips (95%) at a mean interval of 9.2 weeks (range, 5-9 weeks). Two patients underwent repeat radical debridement with removal of all components before reimplantation for persistent clinical evidence of infection. Thirty-three of the 41 hips (81%) were infection free at most recent follow-up. The mean postoperative Harris hip score at most recent evaluation was 63.6 (range, 24-100).

CONCLUSION

Eradication of periprosthetic joint infections, while minimizing patient morbidity, continues to be a challenge. Partial 2-stage exchange may be considered in cases where removal of a well-fixed femoral component may result in significant bony destruction.

Fibrin as a Multipurpose Physiological Platform for Bone Tissue Engineering and Targeted Delivery of Bioactive Compounds

Although bone graft is still considered as the gold standard method, bone tissue engineering offers promising alternatives designed to mimic the extracellular matrix (ECM) and to guide bone regeneration process. In this attempt, due to their similarity to the ECM and their low toxicity/immunogenicity properties, growing attention is paid to natural polymers. In particular, considering the early critical role of fracture hematoma for bone healing, fibrin, which constitutes blood clot, is a candidate of choice. Indeed, in addition to its physiological roles in bone healing cascade, fibrin biochemical characteristics make it suitable to be used as a multipurpose platform for bioactive agents’ delivery. Thus, taking advantage of these key assets, researchers and clinicians have the opportunity to develop composite systems that might further improve bone tissue reconstruction, and more generally prevent/treat skeletal disorders.