Laboratory Value Effectiveness in Predicting Early Postoperative Periprosthetic Joint Infection After Total Hip Arthroplasty

Neutrophil-Lymphocyte Ratio as Predictor for Acute Infection After Primary Total Joint Arthroplasty in Rheumatoid Arthritis Patients

OBJECTIVES

Preoperative levels of certain inflammatory markers in the blood can predict acute infection after primary total joint arthroplasty in patients without inflammatory disease, but whether they can do so in patients with rheumatoid arthritis is unclear. The objectives of this study were to determine whether, with appropriate cut-off values, (1) preoperative levels of NLR predicted postoperative acute infection; and (2) preoperative plasma fibrinogen, monocyte-lymphocyte ratio, C-reactive protein or erythrocyte sedimentation rate predicted postoperative acute infection.

METHODS

We retrospectively analyzed 964 patients with rheumatoid arthritis who underwent primary total joint arthroplasty at our hospital between January 2010 and November 2020. We compared preoperative levels of inflammatory markers including neutrophil-lymphocyte ratio (NLR), monocyte-lymphocyte ratio (MLR), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), plasma fibrinogen (FIB) between patients who suffered acute infection or not within 90 days after surgery. The ability of markers to predict infection was assessed in terms of the area under receiver operating characteristic curves (AUC) based on optimal cut-off values determined from the Youden index.

RESULTS

Among the 964 patients, 27 (2.8%) experienced acute infection. Preoperative levels of individual inflammatory markers predicted infection with the following AUCs and cut-off values: NLR, 0.704 (cut-off: 2.528); MLR, 0.608 (0.2317); CRP, 0.516 (4.125 mg/L); ESR, 0.533 (66.5 mm/h); and FIB, 0.552 (3.415 g/L). The neutrophil-lymphocyte ratio showed diagnostic sensitivity of 92.6% and specificity of 43.3%, while the monocyte-lymphocyte ratio showed sensitivity of 77.8% and specificity of 46.3%.

CONCLUSION

The preoperative NLR shows some ability to predict acute infection after total joint arthroplasty in patients with rheumatoid arthritis. Monitoring this ratio, perhaps in conjunction with other markers not analyzed here, may be useful for optimizing the timing of surgery in order to minimize risk of postoperative infection.

Clinical Benefit of Using Differential Cutoff Values of Synovial C-Reactive Protein in Acute and Chronic Infected as Well as Aseptic Hip and Knee Revision Arthroplasties

BACKGROUND

It is unclear whether cutoff values for synovial C-reactive protein (syCRP) differ between acute and chronic infected as well as aseptic revision total hip arthroplasty (rTHA) and revision total knee arthroplasty (rTKA). We aimed to evaluate this and to compare the diagnostic accuracy of syCRP with serum C-reactive protein (seCRP), synovial white blood cell count, and polymorphonuclear leukocyte percentage (syPMN%).

METHODS

A total of 387 revision arthroplasties (83 rTHA, 304 rTKA) were analyzed for seCRP, syCRP, synovial white blood cell, syPMN%, and culture results. Using the International Consensus Meeting 2018 periprosthetic joint infection (PJI) criteria, 189 (42 rTHA, 147 rTKA) were classified as infected, and 198 (41 rTHA, 157 rTKA) were aseptic revisions. Diagnostic accuracy was assessed using receiver operating characteristic curves and area under the curve (AUC).

RESULTS

The optimal syCRP cutoff for PJI diagnosis among rTHA and rTKA < 90 days was 9.05 mg/L (AUC: 0.85) and 4.95 mg/L (AUC: 0.92), respectively. For > 90 days, the optimal syCRP cutoff was 3.00 mg/L (AUC: 0.90) for THA and 1.65 mg/L (AUC: 0.88) for TKA. In early and late acute PJI (n = 48), syCRP (45 of 48 = 94%) showed a higher positivity rate than seCRP (43 of 48 = 90%), WBC (38 of 48 = 79%), and PMN% (42 of 48 = 88%). A similar trend was observed in chronic PJI (n = 141): syCRP (110 of 141 = 78%), seCRP (104 of 141 = 74%), WBC (105 of 141 = 74%), and PMN% (101 of 141 = 72%). Among 189 confirmed PJIs, both WBC and PMN% were negative in 34 of 189 (18%), of which syCRP and seCRP were positive in 13 of 34 (38%) and 10 of 34 (29%), respectively.

CONCLUSIONS

The syCRP may be useful as a supplementary biomarker in cases with suspected PJI, but normal synovial cell count. Our data suggest that different cutoff values based on the type of joint and the chronicity of rTHA and rTKA are clinically useful.

Synovial absolute polymorphonuclear neutrophil cell count: A simple and inexpensive marker for diagnosing periprosthetic hip and knee joint infections

PURPOSE

This study aimed to establish the optimal cutoff value for synovial absolute polymorphonuclear neutrophil (APMN) count in distinguishing between septic and aseptic hip and knee revision arthroplasties. We also investigated its effectiveness as an indicator in revision arthroplasties with challenging microbiological findings, including (i) aseptic cases with a single unexpected positive intraoperative culture (UPICs), (ii) septic cases with unexpected negative ICs (UNICs) and (iii) infections caused by high- and low-virulent pathogens.

METHODS

A total of 616 revision arthroplasties (177:hip, 439:knee) included. Using European Bone and Joint Infection Society (EBJIS) criteria, 325 (52.8%) were classified as infection confirmed, 271 (44%) infection unlikely and 20 (3.2%) as infection likely. International Consensus Meeting (ICM) 2018 criteria classified 308 (50%) as infected, 269 (43.7%) not infected, and 39 (6.3%) as inconclusive. Diagnostic accuracy was assessed through receiver operating characteristic curves and area under the curve (AUC).

RESULTS

Optimal APMN count thresholds using EBJIS criteria in hip and knee joints were 783.6 cells/µL (AUC: 0.92) and 549 cells/µL (AUC: 0.91), respectively. With the ICM criteria, its optimal cutoff values remained unchanged, except for the knee, which shifted to 594.2 cells/µL. Comparing UPICs to other aseptic cases showed no significant median APMN count differences when both criteria's applied, potentially ruling out infection suspicion. In septic cases, APMN counts differed between UNICs and culture positives but were statistically significant with EBJIS criteria (Hip:p = 0.01, Knee:p = 0.03) but not with ICM (p = 0.08). Median APMN counts were significantly elevated in high-virulent compared to low-virulent organisms, with similar trends in most of the other markers. Compared to alpha-defensin, APMN count exhibited better AUC, sensitivity and negative predictive value.

CONCLUSIONS

The APMN count represents a simple and inexpensive method that may serve as a complementary diagnostic marker in hip and knee revision arthroplasties with challenging microbiological findings.

LEVEL OF EVIDENCE

Level III, retrospective study.

Prognostic Value of C-Reactive Protein in Primary Total Hip Arthroplasty

Background/Objectives: Periprosthetic joint infections (PJIs) are feared complications in arthroplasty and are associated with an increased mortality rate. PJI prevention is of paramount importance since treatment is difficult. In case of an infection, it is crucial to diagnose it at an early stage in order to initiate adequate therapy. The Musculoskeletal Infection Society (MSIS) proposed a catalog of different major and minor diagnostic criteria in 2011 to define a PJI. They were adapted in the following years. One of these criteria is the blood level of C-reactive protein (CRP). CRP is a non-specific acute-phase protein that also increases in response to various non-infectious inflammatory responses. CRP is also routinely obtained prior to total hip arthroplasty (THA) to screen for possible contraindications for arthroplasty such as an acute infection. The validity of this approach has rarely been investigated. The aim of this study was to evaluate the diagnostic value of perioperative CRP in patients receiving a THA. Methods: A total of 239 patients were included in this study and retrospectively analyzed. CRP values were obtained preoperatively and three values postoperatively. Sensitivity, specificity, area under the curve (AUC) and optimal thresholds were calculated. Results: In the whole group, 10 patients developed a PJI. No significance was demonstrated between patients without and with later PJI in terms of preoperative CRP (p = 0.182), postoperative CRP (p = 0.167), relative CRP increase (p = 0.684) and respective CRP differences (p = 0.456). We were not able to find cut-off values with adequate sensitivity and specificity. Conclusions: Perioperative CRP values do not seem to be helpful in predicting further PJI. Rather, they should be used as a screening tool to detect ongoing infections in the individual patient prior to THA. This trial should encourage studies with more statistical power due to the small effect sizes.

How Reliable Is the Absolute Synovial Polymorphonuclear Neutrophil Cell Count in Diagnosing Periprosthetic Joint Infection?

BACKGROUND

Diagnosing periprosthetic joint infection (PJI) is a daunting task for even the most experienced orthopedic surgeons, as there is currently no test available that can provide absolute accuracy. Utilizing an established synovial indicator for detecting PJI without incurring additional costs or resources would be the optimal solution for predicting the presence of infection. Therefore, we hypothesized that synovial absolute neutrophil count (ANC) would improve the diagnostic accuracy of chronic knee and hip PJI.

METHODS

The study included 260 patients (134 men and 126 women, mean age of 70 years [range, 26 to 89]) who underwent aspiration during preoperative workup. Of these, 109 patients (41.9%) were diagnosed with chronic PJI (50 knees, 59 hips), and 151 patients (58.1%) were diagnosed as aseptic (94 knees, 57 hips). Data obtained from all patients included age, sex, procedure type (total hip or total knee arthroplasty), operation side, synovial white blood cell count (cells/μL), synovial polymorphonuclear cells percentage, and synovial α-defensin immunoassay value at the admission were retrieved from the electronic medical record.

RESULTS

The calculated optimal threshold for synovial ANC of 1,415.5 cells/μL was associated with an area under the receiver operating characteristic curve (AUC) of 0.930 for chronic knee PJI diagnosis. The calculated optimal threshold for synovial ANC of 2,247 cells/μL was associated with an AUC of 0.905 for chronic hip PJI diagnosis.

CONCLUSIONS

This study has conclusively shown that the synovial ANC serves as a valuable marker in the complicated diagnosis of PJI. This highly effective and efficient approach should be utilized for obtaining further information through standard tests, thereby ruling out the possibility of PJI.

LEVEL OF EVIDENCE

III.

Diagnostic cutoff values of synovial fluid biomarkers for acute postoperative prosthetic joint infection: a systematic review and meta-analysis

Introduction: The assessment of white blood cell (WBC) count and polymorphonuclear cell (PMN) percentage in synovial fluid can help in the diagnosis of acute postoperative peri-prosthetic joint infection (PJI). Their cutoff values, which would differ from those for chronic PJI, have not yet been determined in acute postoperative PJI. The aim of this study was (1) to analyse studies reporting the optimal cutoff values for WBC count and the PMN percentage in synovial fluid and (2) to determine which is the best diagnostic tool for acute postoperative PJI. Methods: We performed a systematic review (SR) of primary studies analysing WBC count and the PMN percentage for diagnosis of acute postoperative PJI. A search was performed in MEDLINE and EMBASE. We studied the risk of bias and quality assessment. We extracted data on cutoff values, sensitivity, specificity, positive and negative predictive value, area under the curve, and accuracy. We calculated the diagnosis odds ratio (DOR), performed the meta-analysis and summarized receiver operating curves (sROCs) for WBC count and the PMN percentage. Results: We included six studies. WBC count showed a DOR of 123.61 (95 % CI: 55.38-275.88), an sROC with an area under the curve (AUC) of 0.96 (SE: 0.009) and a Q index of 0.917. The PMN percentage showed a summary DOR of 18.71 (95 % CI: 11.64-30.07), an sROC with an AUC 0.88 (SE: 0.018) and a Q index of 0.812. Conclusion: We concluded that WBC count and the PMN percentage are useful tests for the diagnosis of acute PJI; WBC is the more powerful of the two. Studies centred on other synovial fluid biomarkers not yet studied could help in this diagnosis.

Dynamics of C-reactive protein level after orthopedic surgeries

Background

Only two studies present the results of the dynamics of C-reactive protein (CRP) after a large number of orthopedic surgeries. The aim of the study was to investigate the dynamics of CRP levels and determine the influence of various factors on the CRP level after various orthopedic surgeries using big data tools.

Methods

A total of 16042 operated patients were included in the study.

Results

The tendency of peak values to increase by 2-3 days after surgery with subsequent decrease was the same in all subgroups without surgical site infections (SSI). In patients with SSI, the higher preoperative CRP level changed to a peak on day 3 after surgery with a subsequent drop and increase after day 6 in case of probably unsuccessful sanitation. The peak value of CRP significantly correlates with the duration of surgery (r = 0.1072, p < 0,0001). Older patients tend to exhibit higher CRP value (r = 0.2219, p < 0.001). The peak values of CRP in women were significantly greater than those in men.

Conclusion

In cases without SSI, the peak of CRP values occurs on the second or third day after surgery, a secondary increase in CRP levels may indicate a risk of complications. The peak CRP value correlates with the duration of surgery. In clinical practice, relationship between gender, age and the level of CRP should not be one of the indicators influencing the assessment of the risk of a threat to the patient's health, since the results of various studies are contradictory.

Diagnostic Utility and Thresholds for Commonly Obtained Serum and Synovial Markers Prior to Reimplantation in Periprosthetic Joint Infection

BACKGROUND

Accurate diagnosis of persistent periprosthetic joint infection (PJI) during 2-stage exchange remains a challenge. This study evaluated the diagnostic performance and thresholds of several commonly obtained serum and synovial markers to better guide reimplantation timing.

METHODS

This was a retrospective review of 249 patients who underwent 2-stage exchange with antibiotic spacers for PJI. Serum and synovial markers analyzed included white blood cell (WBC) count, polymorphonuclear percentage (PMN%), neutrophil-to-lymphocyte ratio (NLR), and absolute neutrophil count (ANC). Serum markers analyzed were erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), as well as percentage change in ESR and CRP from initial diagnosis to reimplantation. Area under the curve (AUC) analyses were performed to determine diagnostic accuracy of detecting PJI.

RESULTS

In TKAs, synovial ANC and WBC had the highest AUCs (0.76), with thresholds of 2,952 and 3,800 cells/μL, respectively. The next best marker was serum CRP (0.73) with a threshold of 5.2 mg/dL. In THAs, serum CRP had the highest AUC (0.84) with a threshold of 4.3 mg/dL, followed by synovial PMN% (0.80) with a threshold of 77%. Percentage change in serum ESR or CRP provided low diagnostic value overall.

CONCLUSION

Regarding serum markers, CRP consistently performed well in detecting persistent PJI in patients with antibiotic spacers. Absolute values of serum CRP and ESR had better diagnostic value than trends for guiding reimplantation timing. Diagnostic performance differed with joint type; however, synovial markers outperformed serum counterparts. No marker alone can be utilized to diagnose residual PJI in these patients, and further work is needed in this domain.

Synovial Fluid Absolute Neutrophil Count and Neutrophil-To-Lymphocyte Ratio are not Superior to Polymorphonuclear Percentage in Detecting Periprosthetic Joint Infection

BACKGROUND

Serum and synovial biomarkers are currently used to diagnose periprosthetic joint infection (PJI). Serum neutrophil-to-lymphocyte ratio (NLR) has shown promise as an inexpensive test in diagnosing infection, but there are no reports of synovial NLR or absolute neutrophil count (ANC) for diagnosing chronic PJI. The purpose of this study was to investigate the diagnostic potential of both markers.

METHODS

A retrospective review of 730 patients who underwent total joint arthroplasty and subsequent aspiration was conducted. Synovial white blood cell (WBC) count, synovial polymorphonuclear percentage (PMN%), synovial NLR, synovial ANC, serum erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), serum WBC, serum PMN%, serum NLR, and serum ANC had their utility in diagnosing PJI examined by area-under-the-curve analyses (AUC). Pairwise comparisons of AUCs were performed.

RESULTS

The AUCs for synovial WBC, PMN%, NLR, and ANC were 0.84, 0.84, 0.83, and 0.85, respectively. Synovial fluid ANC was a superior marker to synovial NLR (P = .027) and synovial WBC (P = .003) but not PMN% (P = .365). Synovial NLR was inferior to PMN% (P = .006) but not different from synovial WBC (P > .05). The AUCs for serum ESR, CRP, WBC, PMN%, NLR, and ANC were 0.70, 0.79, 0.63, 0.72, 0.74, and 0.67, respectively. Serum CRP outperformed all other serum markers (P < .05) except for PMN% and NLR (P > .05). Serum PMN% and NLR were similar to serum ESR (P > .05).

CONCLUSION

Synovial ANC had similar performance to PMN% in diagnosing chronic PJI, whereas synovial NLR was a worse diagnostic marker. The lack of superiority to synovial PMN% limits the utility of these tests compared to established criteria.

Diagnostic Performance of Neutrophil to Lymphocyte Ratio, Monocyte to Lymphocyte Ratio, Platelet to Lymphocyte Ratio, and Platelet to Mean Platelet Volume Ratio in Periprosthetic Hip and Knee Infections: A Systematic Review and Meta-Analysis

The current literature on the diagnosis of periprosthetic joint infection provides controversial evidence on the diagnostic accuracy of MLR, NLR, PVR, and PLR. Therefore, this critical literature search and meta-analysis was aimed to summarize the diagnostic accuracy of these biomarkers for the diagnosis of hip and knee prosthetic infection. According to the PRISMA flowchart, we searched MEDLINE, Scopus, and Web of Science, for studies on these ratios for diagnosing PJI. Sensitivity, specificity, positive and negative likelihood ratio, diagnostic odds ratio, and AUC were analyzed. We included 11 articles in our meta-analysis, including 7537 patients who underwent total hip and knee arthroplasties; among these, 1974 (26%) patients reported a joint infection. The pooled sensitivity and specificity were 0.72 and 0.74, respectively, for NLR, 0.72 and 0.77 for PVR, and 0.77 and 0.75 for PLR. The sensitivity of MLR ranges from 0.54 to 0.81, while the specificity ranges from 0.78 to 0.81. Regarding the evaluation of AUCs, the best diagnostic performance was achieved by MLR (AUC = 0.77) followed by PLR (AUC = 0.75), NLR (AUC = 0.73), and PVR (AUC = 0.70). This meta-analysis demonstrates a fair diagnostic accuracy of these ratios, thus not being useful as a screening tool.