Imaging of low-grade bone infection with a technetium-99m labelled monoclonal anti-NCA-90 Fab' fragment in patients with previous joint surgery

Nuclear Medicine Scans in Total Joint Replacement

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A 3-phase bone scan is a potential first-line nuclear medicine study for pain after total joint arthroplasty (TJA) when there is concern for periprosthetic joint infection or aseptic loosening.

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In patients who have a positive bone scintigraphy result and suspected infection of the joint, but where aspiration or other studies are inconclusive, labeled leukocyte scintigraphy with bone marrow imaging may be of benefit.

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Magnetic resonance imaging (MRI), while not a nuclear medicine study, also shows promise and has the advantage of providing information about the soft tissues around a total joint replacement.

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Radiotracer uptake patterns in scintigraphy are affected by the prosthesis (total knee arthroplasty [TKA] versus total hip arthroplasty [THA]) and the use of cement.

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Nuclear medicine scans may be ordered 1 year postoperatively but may have positive findings that are due to normal physiologic bone remodeling. Nuclear studies may be falsely positive for up to 2 years after TJA.

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Single-photon emission computed tomography (SPECT) combined with computed tomography (CT) (SPECT/CT), fluorine-18 fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT, and MRI show promise; however, more studies are needed to better define their role in the diagnostic workup of pain after TJA.

18F-FDG-PET uptake in non-infected total hip prostheses

Background and purpose - ¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) can be used in the diagnostic work-up of a patient with suspected periprosthetic joint infection (PJI) but, due to a lack of accurate interpretation criteria, this technique is not routinely applied. Since the physiological uptake pattern of FDG around a joint prosthesis is not fully elucidated, we determined the physiological FDG uptake in non-infected total hip prostheses. Patients and methods - Patients treated with primary total hip arthroplasty (1995-2016) who underwent a FDG-PET/CT for an indication other than a suspected PJI were retrospectively evaluated. Scans were both visually and quantitatively analyzed. Semi-quantitative analysis was performed by calculating maximum and peak standardized uptake values (SUV_max and SUV_peak) by volume of interests (VOIs) at 8 different locations around the prosthesis. Results - 58 scans from 30 patients were analyzed. In most hips, a diffuse heterogeneous uptake pattern around the prosthesis was observed (in 32/38 of the cemented prostheses, and in 16/20 of the uncemented prostheses) and most uptake was located around the neck of the prosthesis. The median SUV_max in the cemented group was 2.66 (95% CI 2.51-3.10) and in the uncemented group 2.87 (CI 2.65-4.63) (Median difference = -0.36 [CI -1.2 to 0.34]). In uncemented prostheses, there was a positive correlation in time between the age of the prosthesis and the FDG uptake (r_s = 0.63 [CI 0.26-0.84]). Interpretation - Our study provides key data to develop accurate interpretation criteria to differentiate between physiological uptake and infection in patients with a prosthetic joint.

Synovial Calprotectin: An Inexpensive Biomarker to Exclude a Chronic Prosthetic Joint Infection

BACKGROUND

To diagnose or exclude a chronic prosthetic joint infection (PJI) can be a clinical challenge. Therefore, sensitive and specific biomarkers are needed in the diagnostic work-up. Calprotectin is a protein with antimicrobial properties and is released by activated neutrophils, making it a specific marker for infection. Because of its low costs and ability to obtain a quantitative value as a point of care test, it is an attractive marker to use in clinical practice. In addition, the test is already used in routine care in most hospitals for other indications and therefore easy to implement.

METHODS

Between June 2015 and June 2017 we collected synovial fluid of all consecutive patients who underwent revision surgery of a prosthetic joint because of chronic pain with or without prosthetic loosening. Synovial calprotectin was measured using a lateral flow immunoassay. A PJI was defined by the diagnostic criteria described by the Musculoskeletal Infection Society.

RESULTS

Fifty-two patients with chronic pain were included. A PJI was diagnosed in 15 of 52 (29%) patients. The median calprotectin in the PJI group was 859 mg/L (interquartile range 86-1707) vs 7 mg/L (interquartile range 3-25) in the control group (P < .001). With a cut-off value of 50 mg/L, synovial calprotectin showed a sensitivity, specificity, positive predictive value, and negative predictive value of 86.7%, 91.7%, 81.3%, and 94.4%, respectively.

CONCLUSION

Synovial calprotectin is a useful and cheap biomarker to use in the diagnostic work-up of patients with chronic pain, especially to exclude a PJI prior to revision surgery.

Withholding Preoperative Antibiotic Prophylaxis in Knee Prosthesis Revision: A Retrospective Analysis on Culture Results and Risk of Infection

BACKGROUND

A significant amount of patients undergoing revision surgery of a prosthetic joint turn out to have an infection. Withholding preoperative antibiotic prophylaxis in these patients to optimize culture yield during revision surgery remains a matter of debate. The aim of our study was to determine (1) the rate of positive intraoperative cultures with or without preoperative antibiotic prophylaxis and (2) the incidence of a prosthetic joint infection (PJI) during the follow-up in the 2 groups.

METHODS

Medical files of patients in whom preoperative antibiotic prophylaxis was withheld until culture samples were taken (2007-2010, n = 284) and in whom antibiotic prophylaxis was given during the induction of anesthesia (2010-2013, n = 141) were retrospectively reviewed.

RESULTS

The percentage of ≥1 positive cultures was the same in the group without (26%) and with preoperative prophylaxis (27%; P value, .7). PJI was diagnosed during revision surgery according to the Musculoskeletal Infection Society criteria in 6.7% patients not receiving preoperative prophylaxis and in 7.0% receiving it (P value, .79). We found no important differences in the type of microorganisms that were isolated in both groups. During a 3-month follow-up, an early PJI developed in patients undergoing total revision surgery in 6.4% of the nonpreoperative prophylaxis group vs 1.6% in the preoperative prophylaxis group (P value, .1).

CONCLUSION

Preoperative antibiotic prophylaxis does not reduce culture yield in patients undergoing knee revision surgery. Our data show a trend toward a higher PJI rate in the postoperative period of total revision surgery when preoperative prophylaxis is withheld.

What is the Accuracy of Nuclear Imaging in the Assessment of Periprosthetic Knee Infection? A Meta-analysis

BACKGROUND

In the assessment of possible periprosthetic knee infection, various imaging modalities are used without consensus regarding the most accurate technique.

QUESTIONS/PURPOSES

To perform a meta-analysis to compare the accuracy of various applied imaging modalities in the assessment of periprosthetic knee infection.

METHODS

A systematic review and meta-analysis was conducted with a comprehensive search of MEDLINE and Embase^® in accordance with the PRISMA and Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) recommendations to identify clinical studies in which periprosthetic knee infection was investigated with different imaging modalities. The sensitivity and specificity of each imaging technique were determined and compared with the results of microbiologic and histologic analyses, intraoperative findings, and clinical followup of more than 6 months. A total of 23 studies, published between 1990 and 2015, were included for meta-analysis, representing 1027 diagnostic images of symptomatic knee prostheses. Quality of the included studies showed low concerns regarding external validity, whereas internal validity indicated more concerns regarding the risk of bias. The most important concerns were found in the lack of uniform criteria for the diagnosis of a periprosthetic infection and the flow and timing of the included studies. Differences among techniques were tested at a probability less than 0.05 level. Where there was slight overlap of confidence intervals for two means, it is possible for the point estimates to be statistically different from one another at a probability less than 0.05. The z-test was used to statistically analyze differences in these situations.

RESULTS

Bone scintigraphy was less specific than all other modalities tested (56%; 95% CI, 0.47-0.64; p < 0.001), and leukocyte scintigraphy (77%; 95% CI, 0.69-0.85) was less specific than antigranulocyte scintigraphy (95%; 95% CI, 0.88-0.98; p < 0.001) or combined leukocyte and bone marrow scintigraphy (93%; 95% CI, 0.86-0.97; p < 0.001). Fluorodeoxyglucose positron emission tomography (FDG-PET) (84%; 95% CI, 0.76-0.90) was more specific than bone scintigraphy (56%; 95% CI, 0.47-0.64; p < 0.001), and less specific than antigranulocyte scintigraphy (95%; 95% CI, 0.88-0.98; p = 0.02) and combined leukocyte and bone marrow scintigraphy (93%; 95% CI, 0.86-0.97; p < 0.001). Leukocyte scintigraphy (88%; 95% CI, 0.81-0.93; p = 0.01) and antigranulocyte scintigraphy (90%; 95% CI, 0.78-0.96; p = 0.02) were more sensitive than FGD-PET (70%; 95% CI, 0.56-0.81). However, because of broad overlapping of confidence intervals, no differences in sensitivity were observed among the other modalities, including combined bone scintigraphy (93%; 95% CI, 0.85-0.98) or combined leukocyte and bone marrow scintigraphy (80%; 95% CI, 0.66-0.91; p > 0.05 for all paired comparisons).

CONCLUSIONS

Based on current evidence, antigranulocyte scintigraphy and combined leukocyte and bone marrow scintigraphy appear to be highly specific imaging modalities in confirming periprosthetic knee infection. Bone scintigraphy was a highly sensitive imaging technique but lacks the specificity needed to differentiate among various conditions that cause painful knee prostheses. FDG-PET may not be the preferred imaging modality because it is more expensive and not more effective in confirming periprosthetic knee infection.

LEVEL OF EVIDENCE

Level III, diagnostic study.

The Accuracy of Imaging Techniques in the Assessment of Periprosthetic Hip Infection: A Systematic Review and Meta-Analysis

BACKGROUND

Various imaging techniques are used for excluding or confirming periprosthetic hip infection, but there is no consensus regarding the most accurate technique. The objective of this study was to determine the accuracy of current imaging modalities in diagnosing periprosthetic hip infection.

METHODS

A systematic review and meta-analysis of the literature was conducted with a comprehensive search of MEDLINE and Embase to identify clinical studies in which periprosthetic hip infection was investigated with different imaging modalities. The sensitivity and specificity of each imaging technique were determined and compared with the results of microbiological and histological analysis, intraoperative findings, and clinical follow-up of >6 months.

RESULTS

A total of 31 studies, published between 1988 and 2014, were included for meta-analysis, representing 1,753 hip prostheses. Quality assessment of the included studies identified low concerns with regard to external validity but more concerns with regard to internal validity including risk of bias (>50% of studies had insufficient information). No meta-analysis was performed for radiography, ultrasonography, computed tomography, and magnetic resonance imaging because of insufficient available clinical data. The pooled sensitivity and specificity were 88% (95% confidence interval [CI], 81% to 94%) and 92% (95% CI, 88% to 96%), respectively, for leukocyte scintigraphy; 86% (95% CI, 80% to 90%) and 93% (95% CI, 90% to 95%) for fluorodeoxyglucose positron emission tomography (FDG PET); 69% (95% CI, 58% to 79%) and 96% (95% CI, 93% to 98%) for combined leukocyte and bone marrow scintigraphy; 84% (95% CI, 70% to 93%) and 75% (95% CI, 66% to 82%) for antigranulocyte scintigraphy; and 80% (95% CI, 72% to 86%) and 69% (95% CI, 64% to 73%) for bone scintigraphy.

CONCLUSIONS

Of the currently used imaging techniques, leukocyte scintigraphy has satisfactory accuracy in confirming or excluding periprosthetic hip infection. Although not significantly different, combined leukocyte and bone marrow scintigraphy was the most specific imaging technique. FDG PET has an appropriate accuracy in confirming or excluding periprosthetic hip infection, but may not yet be the preferred imaging modality because of limited availability and relatively higher cost.

LEVEL OF EVIDENCE

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

Infection after total knee replacement: diagnosis and treatment

Infection after total knee replacement (IATJ) is a rare complication. It is associated with increased morbidity and mortality increasing the final costs. Gram positive coccus and Staphylococcus coagulase-negative and Staphylococcus aureus are the most common isolated germs (>50% of the cases). Conditions related to the patient, to the surgical procedure and even to the post op have been identified as risk factors to IATJ. Many complementary methods together with clinical symptoms are useful to a proper diagnosis. Treatment for IATJ must be individualized but generally is a combination of systemic antibiotic therapy and surgical treatment. Prosthesis exchange in one or two stages is the first choice procedure. Debridement with prosthesis retention is an option in acute cases with stable implants and antibiotic sensible germs.

Use of anti-granulocyte scintigraphy with 99mTc-labeled monoclonal antibodies for the diagnosis of periprosthetic infection in patients after total joint arthroplasty: a diagnostic meta-analysis

The accurate diagnosis of periprosthetic joint infections (PJI) is crucial for therapy and the prevention of complications. No diagnostic test of PJI is 100% accurate. The aim of this study was to assess the use of anti-granulocyte scintigraphy using 99 mTc-labeled monoclonal antibodies to diagnose PJI after total joint arthroplasty. A systematic search of all relevant studies published through January 2013 was conducted using the MEDLINE, EMBASE, OVID, and ScienceDirect databases. Observational studies that assessed the accuracy of the anti-granulocyte scintigraphy with monoclonal antibodies or antibody fragments labeled with technetium 99 m in diagnosis for PJI and provided data on specificity and sensitivity were identified. Standard methods recommended for meta-analysis of diagnostic accuracy were used. Nineteen studies were eligible for inclusion. The results demonstrated that the area under the summary receiver operator curve was 0.88, and the diagnostic accuracy (Q*) was 0.81. Additionally, the diagnostic odds ratio (DOR) was 18.76 with a corresponding 95% confidence interval of 10.45–33.68. The pooled sensitivity and specificity of the diagnostic method for the diagnosis of PJI were 83% and 79%, respectively, while the pooled positive likelihood ratio (PLR) was 3.56, and the negative likelihood ratio (NLR) was 0.26. Anti-granulocyte scintigraphy using 99 mTc-labeled monoclonal antibodies has a reasonable role in the diagnosis of PJI after total joint arthroplasty. Due to the limitations of the present meta-analysis, additional high-quality original studies are required to confirm the predictive value.

Diagnosis of periprosthetic joint infections in clinical practice

The diagnosis of a periprosthetic joint infection (PJI) can be challenging, either because of the variable clinical presentation or because of previous antimicrobial treatment interfering with the detection of the pathogen. In recent years, various means to diagnose PJI have been analyzed. These include invasive and non-invasive laboratory tests, imaging procedures, and novel techniques such as sonication of implants and the use of molecular microbiology. In this review, both established and novel diagnostic procedures are presented. An algorithm for detecting PJI in patients with acute and chronic symptoms is proposed.

Detection of low-grade prosthetic joint infections using 99mTc-antigranulocyte SPECT/CT: initial clinical results

PURPOSE

Low-grade joint infections are characterized by infiltration of granulocytes, which mediate aspects of inflammatory changes. We evaluated retrospectively the contribution of SPECT/CT as an addition to planar scintigraphy with (99m)Tc-labelled antigranulocyte antibodies for diagnosing and localizing low-grade joint infections.

METHODS

Planar scintigraphy using (99m)Tc-labelled antigranulocyte BW 250/183 antibodies was performed in 31 patients with suspected joint infections at 5 min, 5 h and 24 h after injection, with additional SPECT/CT performed 6 h after injection. With reference to gold standard clinical data, we assessed the diagnostic sensitivity of scintigraphy alone and in conjunction with SPECT/CT.

RESULTS

Joint infections were diagnosed clinically in 9 of the 31 patients (1 hip and 8 knee prostheses). Planar scintigraphy revealed 6 true-positives, 13 true-negatives, 9 false-positives and 3 false-negative results, indicating sensitivity, specificity, positive and negative predictive values of, respectively, 0.66, 0.60, 0.4 and 0.81. With the addition of SPECT images, corresponding sensitivity, specificity, positive and negative predictive values increased to 0.89, 0.45, 0.40 and 0.91. Implementation of fused SPECT/CT led to a further increase to 0.89, 0.73, 0.57 and 0.94.

CONCLUSION

Relative to planar scintigraphy, SPECT with and without CT substantially improved the utility of imaging with (99m)Tc-labelled antigranulocyte antibodies for diagnosis and localization of suspected joint infections. Optimal accuracy was obtained through image fusion, which permitted anatomical allocation of foci of pathological tracer accumulation as well as providing information on the extent of the infection. This imaging method seems suited for selection of patients requiring surgical therapy.

Infection and musculoskeletal conditions: Prosthetic-joint-associated infections

In patients with osteoarthritis or arthritis, prosthetic joint replacement is increasingly used to alleviate pain and to improve mobility. The most important risk factors are comorbidity and prior joint replacement (revision surgery). Diagnosis of prosthetic-joint-associated infection is difficult, because the infecting agent may be missed in synovial fluid due to its exclusive presence as a device-associated biofilm. Implant-associated infections are difficult to treat because of their resistance to natural host defence mechanisms and to most antibiotics. In staphylococcal implant-associated infections a rifampin combination should be used, because this drug has an excellent efficacy on surface-adhering microorganisms. Antimicrobial therapy must always be combined with the correct surgical treatment which is chosen according to an algorithm. The use of antibiotics during procedures with potential bacteraemia is controversial because evidence for its need is lacking. In contrast, during sepsis rapid antibiotic therapy is needed to prevent haematogenous seeding on the artificial joint.

Prosthesis Infection: Diagnosis after Total Joint Arthroplasty with Antigranulocyte Scintigraphy with99mTc-labeled Monoclonal Antibodies—A Meta-Analysis

PURPOSE

To perform a meta-analysis of diagnostic studies regarding the accuracy of antigranulocyte scintigraphy (AGS) with monoclonal antibodies in the identification of prosthesis infection after total hip or knee arthroplasty.

MATERIALS AND METHODS

PubMed and EMBASE searches were conducted for the identification of relevant studies. Data on the diagnostic performance of AGS with monoclonal antibodies were combined quantitatively across eligible studies, and the overall sensitivity and specificity, along with summary receiver operating characteristic (ROC) curves and likelihood ratios (LRs), were estimated. The above parameters were evaluated for all patients and for various subgroups among the eligible studies. The reference standard used in the individual studies was accepted.

RESULTS

Thirteen eligible studies on nonoverlapping patient groups were included in the meta-analysis; there was a total sample size of 522 implants. The independent random effects summary estimates of sensitivity and specificity were 83% and 80%, respectively. The summary ROC curve estimate for weighted analysis was a sensitivity of 90% for a specificity of 80%. LR syntheses gave a weighted positive LR of 3.99 (95% confidence interval [CI]: 3.13, 5.09) and a weighted negative LR of 0.22 (95% CI: 0.15, 0.34); there was no statistically significant between-study heterogeneity for either metric. Various subgroup analyses did not reveal any statistically significant differences.

CONCLUSION

AGS with monoclonal antibodies had a reasonably high discriminating ability to identify prosthesis infection in patients who underwent total joint arthroplasty.

Bone infection in patients suspected of complicating osteomyelitis: the diagnostic value of dual isotope bone-granulocyte scintigraphy

AIM

The purpose of this study was to evaluate the diagnostic value of dual isotope bone-granulocyte scintigraphy in patients with known bone pathology clinically suspected of osteomyelitis, i.e. complicating osteomyelitis, using per-operative bacterial culture from bone as reference.

METHODS

Simultaneous dual isotope bone-granulocyte scintigraphic images were obtained in 42 consecutive patients in whom conventional X-ray, erythrocyte sedimentation rate, and C-reactive protein were also available. 99mTc MDP bone and 111In labelled granulocyte imaging was obtained simultaneously. The images were interpreted as positive for osteomyelitis if regions of interests of pathologic 111In granulocyte accumulation included 99mTc MDP activity on the bone images (except in the spine).

RESULTS

The sensitivity, specificity, and accuracy were 84, 71 and 79%, respectively, for simultaneous, dual isotope bone-granulocyte scintigraphy, higher than the other diagnostic parameters.

CONCLUSION

Simultaneous bone-granulocyte scintigraphy is a valuable diagnostic tool in diagnosing osteomyelitis complicating other bone pathology with or without soft-tissue infection.

Immunoscintigraphy of septic loosening of knee endoprosthesis: a retrospective evaluation of the antigranulocyte antibody BW 250/183

Immunoscintigraphy with the use of the antigranulocyte antibody BW 250/183 is a reliable method for detecting infection, especially in septic loosening of hip prostheses, for which purpose quantitative interpretation of the time-activity course is employed. Therefore, we retrospectively studied whether similar results could be achieved in knee prostheses. We verified 28 scintigraphic examinations in 26 patients by histology. Scintigraphy was performed during an early (4-6 h post injection) and a late phase (23-25 h post injection). Infection was diagnosed when activity around the knee prosthesis increased by more than 10% compared with bone marrow. We found a sensitivity and a negative predictive value of 100%, a specificity of 80%, a positive predictive value of 81% and an accuracy of 89%. Specificity and accuracy are lower than in the evaluation of hip prostheses; however, in comparison to other scintigraphic modalities, scintigraphy with the antigranulocyte antibody BW 250/183 is superior in excluding infection and has better specificity and accuracy. Therefore, as in the case of hip prostheses, the described methodology appears to be the scintigraphic modality of choice for knee prostheses.

Prosthetic joint infections: bane of orthopedists, challenge for infectious disease specialists

Prosthetic joint infections (PJIs) occur in approximately 1.5%-2.5% of all primary hip or knee arthroplasties. The mortality rate attributed to PJIs may be as high as 2.5%. Substantial morbidity is associated with a loss of mobility, although this is temporary. The costs associated with a single episode of PJI are approximately $50,000 per episode, exclusive of lost wages. Risk factors that increase the occurrence of PJI include revision arthroplasty, time in the operating room, postoperative surgical site infection, and malignancy. Pain is the most consistent symptom. Staphylococcus species are the most common organisms isolated from PJI sites. Two-stage revision is superior to single-stage revision or to debridement with prosthesis retention. Long-term antibiotic suppression and/or arthrodesis are useful for patients too frail to undergo extensive surgery. Using an optimal approach, recurrent infection occurs in <10% of previously infected joints.