Diagnosis of Periprosthetic Joint Infection: The Role of Nuclear Medicine May Be Overestimated

Serum and Synovial Markers in the Diagnosis of Periprosthetic Joint Infection of the Hip, Knee, and Shoulder: An Algorithmic Approach

➤ No single test has demonstrated absolute accuracy for the diagnosis of periprosthetic joint infection (PJI).➤ Physicians rely on a combination of serological tests, synovial markers, and clinical findings plus clinical judgment to help to guide preoperative decision-making.➤ Several organizations have proposed criteria for the diagnosis of hip or knee PJI on which we now rely.➤ Given that shoulder arthroplasty has only recently become popular, it is possible that a shoulder-specific definition of PJI will be introduced in the coming years.➤ Although a number of serum and synovial markers have demonstrated high accuracy for the diagnosis of PJI of the hip and knee, further research is needed in order to identify markers that may be more suitable for the diagnosis of shoulder PJI and for the potential development and identification of specific serological tests as screening tools for PJI.

Diagnostic efficiency of [68 Ga]Ga-DOTA-FAPI-04 in differentiating periprosthetic hip joint infection and aseptic failure

PURPOSE

To assess the efficiency of [68 Ga]Ga-DOTA-FAPI-04 in diagnosing periprosthetic hip joint infection and establish a diagnostic standard of clinical significance based on uptake pattern.

METHODS

[68 Ga]Ga-DOTA-FAPI-04 PET/CT was performed in patients with symptomatic hip arthroplasty from December 2019 to July 2022. The reference standard was based on the 2018 Evidence-Based and Validation Criteria. Two diagnostic criteria, SUVmax and uptake pattern, were used to diagnose PJI. Meanwhile, original data were imported into IKT-snap to draw the view of interest, A.K. was used to extract features of clinical cases, and unsupervised clustering analysis was applied according to the groups.

RESULTS

A total of 103 patients were included, 28 of whom had PJI. The area under the curve of SUVmax was 0.898, which was better than that of all of the serological tests. The cutoff value of SUVmax was 7.53, and the sensitivity and specificity were 100 and 72%, respectively. The sensitivity, specificity and accuracy of the uptake pattern were 100, 93.1 and 95%, respectively. In radiomics analysis, the features of PJI were significantly different from those of aseptic failure.

CONCLUSION

The efficiency of [68 Ga]Ga-DOTA-FAPI-04 PET/CT in diagnosing PJI showed promising results, and the diagnostic criteria of the uptake pattern were more clinically instructive. Radiomics also showed certain application prospects in the field of PJI.

TRIAL REGISTRATION NUMBER

Trial registration: ChiCTR2000041204. Registered 24 September 2019.

Emerging Technologies in Diagnosing Periprosthetic Joint Infections

Periprosthetic joint infection (PJI) is a well-known serious complication following joint replacement surgeries and is responsible for high failure rates of implanted devices. Any delay in the diagnosis can compromise treatment success, putting a huge burden on the patients' wellness and healthcare systems. Diagnosing PJIs is quite complex as there is still no gold standard test to reach the definitive diagnosis in a timely manner. A number of laboratory tests and radiological imaging inventions have evolved in the past few years, requiring consistent updates of the available guidelines to keep up with the latest advances in the field. This article highlights the recent advances in diagnosing PJIs and discusses their validity for use in clinical practice.

The Temporal Impact of Prosthesis Implantation and Semi-Quantitative Criteria on the Diagnostic Efficacy of Triple-Phase Bone Scanning for Periprosthetic Joint Infection

Objective

To evaluate the diagnostic efficacy of triple‐phase bone scanning and the temporal impact of prosthesis implantation on the diagnostic efficacy of triple‐phase bone scanning for periprosthetic joint infection (PJI).

Methods

Patients who were admitted to our hospital for joint pain and dysfunction after total joint arthroplasty between 2014 and 2020 were retrospectively included. Triple‐phase bone scanning was performed, and the blood pool images were evaluated to obtain the semi‐quantitative criteria. The patients were then grouped into six groups according to the time interval from index primary arthroplasty to triple‐phase bone scanning. We examined whether there were significant differences in sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy between the groups.

Results

Overall, 66 patients who underwent total hip arthroplasty (THA) and 74 patients who underwent total knee arthroplasty (TKA) were analyzed. No significant differences were observed between visual analysis and semi‐quantitative measurement in terms of sensitivity, specificity, PPV, NPV, and accuracy. For patients with a time interval from prosthesis implantation to bone scanning of >1 year, visual analysis had a higher PPV (100%) in patients who underwent THA and the use of semi‐quantitative criteria had a higher NPV (85.7%) in patients who underwent TKA.

Conclusion

The semi‐quantitative criteria showed no advantages in the diagnosis of PJI. In addition, triple‐phase bone scanning demonstrated good clinical diagnostic efficacy when the time interval from prosthesis implantation to bone scanning was >1 year.

Diagnosis of prosthetic joint infection at the hip using the standard uptake value of three-phase 99mTc-hydroxymethylene diphosphonate SPECT/CT

PURPOSE

To retrospectively investigate whether the standard uptake value (SUV) of 99mTc-bone single-photon emission computed tomography (SPECT)/CT could be useful for predicting prosthetic joint infection (PJI) at the hip.

PATIENTS AND METHODS

We analyzed the cases of 37 patients with a suspected PJI at the hip who underwent 99mTc-bone SPECT/CT and surgical intervention with pathological and bacterial examinations. We divided the cases into those with and those without a causative bacterium detected in a surgical specimen, i.e., the positive bacterial culture (PBC) group (n = 17) and negative bacterial culture (NBC) group (n = 20). Cases with neutrophilic infiltration of surgical specimen comprised the positive neutrophilic infiltration (PINF) group (n = 18) and those without INF comprised the non-neutrophilic infiltration (NINF) group (n = 19). Quantitative analyses were performed using maximum SUVs and peak SUVs of blood-pool (BP) phase images (SUVmaxBP and SUVpeakBP) and late (LT)-phase images (SUVmaxLT and SUVpeakLT).

RESULTS

Regarding the bacterial cultures, there were significant differences between the PBC and NBC groups in SUVmaxBP (5.26 ± 1.49 vs. 4.21 ± 1.15, respectively; p = 0.019), SUVpeakBP (4.89 ± 1.32 vs. 3.87 ± 1.06, p = 0.012), SUVmaxLT (16.10 ± 6.36 vs. 11.67 ± 4.95, p = 0.026), and SUVpeakLT (14.58 ± 5.83 vs. 10.49 ± 4.31 p = 0.036). Regarding neutrophilic infiltration, there were significant differences between the PINF and NINF groups in SUVmaxBP (5.18 ± 1.48 vs. 4.24 ± 1.19, p = 0.047) and SUVpeakBP (4.78 ± 1.32 vs. 3.92 ± 1.10, p = 0.043).

CONCLUSION

An SUV analysis of 99mTc-bone SPECT/CT is a useful method to differentiate a PJI at the hip from non-infection.

Nuclear imaging does not have clear added value in patients with low a priori chance of periprosthetic joint infection. A retrospective single-center experience

Background: A low-grade periprosthetic joint infection (PJI) may present without specific symptoms, and its diagnosis remains a challenge. Three-phase bone scintigraphy (TPBS) and white blood cell (WBC) scintigraphy are incorporated into recently introduced diagnostic criteria for PJI, but their exact value in diagnosing low-grade PJI in patients with nonspecific symptoms remains unclear. Methods: In this retrospective study, we evaluated patients with a prosthetic joint of the hip or knee who underwent TPBS and/or WBC scintigraphy between 2009 and 2016 because of nonspecific symptoms. We reviewed and calculated diagnostic accuracy of the TPBS and/or WBC scintigraphy to diagnose or exclude PJI. PJI was defined based on multiple cultures obtained during revision surgery. In patients who did not undergo revision surgery, PJI was ruled out by clinical follow-up of at least 2 years absent of clinical signs of infection based on MSIS 2011 criteria. Results: A total of 373 patients were evaluated, including 340 TPBSs and 142 WBC scintigraphies. Thirteen patients (3.5 %) were diagnosed with a PJI. TPBS sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were 71 %, 65 %, 8 % and 98 %, respectively. Thirty-five percent of TPBS showed increased uptake. Stratification for time intervals between the index arthroplasty and the onset of symptoms did not alter its diagnostic accuracy. WBC scintigraphy sensitivity, specificity, PPV and NPV were 30 %, 90 %, 25 % and 94 %, respectively. Conclusion: Nuclear imaging does not have clear added value in patients with low a priori chance of periprosthetic joint infection.

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.

The Role of Imaging Techniques to Define a Peri-Prosthetic Hip and Knee Joint Infection: Multidisciplinary Consensus Statements

Diagnosing a peri-prosthetic joint infection (PJI) remains challenging despite the availability of a variety of clinical signs, serum and synovial markers, imaging techniques, microbiological and histological findings. Moreover, the one and only true definition of PJI does not exist, which is reflected by the existence of at least six different definitions by independent societies. These definitions are composed of major and minor criteria for defining a PJI, but most of them do not include imaging techniques. This paper highlights the pros and cons of available imaging techniques—X-ray, ultrasound, computed tomography (CT), Magnetic Resonance Imaging (MRI), bone scintigraphy, white blood cell scintigraphy (WBC), anti-granulocyte scintigraphy, and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), discusses the added value of hybrid camera systems—single photon emission tomography/computed tomography (SPECT/CT), PET/CT and PET/MRI and reports consensus answers on important clinical questions that were discussed during the Third European Congress on Inflammation/Infection Imaging in Rome, December 2019.

Should scintigraphy be completely excluded from the diagnosis of periprosthetic joint infection?

AIM

To analyse the diagnostic performance of bone and leukocyte scintigraphy for periprosthetic joint infection before excluding the test from routine practice, and to analyse the possible benefit of bone marrow scintigraphy in inconclusive cases.

MATERIALS AND METHODS

From 2012 to 2018, all patients with a total hip or knee arthroplasty who had a bone and leukocyte scintigraphy performed and underwent revision surgery were included. Bone marrow scintigraphy was indicated only in cases in which bone and leukocyte scintigraphy were inconclusive. Diagnosis of periprosthetic joint infection was confirmed by positive intraoperative cultures after revision surgery.

RESULTS

A total of 105 patients were included. Eighteen patients had total hip arthroplasties (18.1%) and 86 had total knee arthroplasties (81.9%). Mean age was 74 years. Nineteen cases were diagnosed with a periprosthetic joint infection. Bone and leukocyte scintigraphy had 64% sensitivity and 97% specificity. Bone marrow scintigraphy increased sensitivity and specificity to 88% and 100%, respectively.

CONCLUSION

Bone and leukocyte scintigraphy possesses high sensitivity and specificity for the diagnosis of chronic periprosthetic joint infection. The additional use of bone marrow scintigraphy significantly increases diagnostic performance. For these reasons, bone scintigraphy is reserved for inconclusive cases of chronic periprosthetic joint infection.

Diagnostic criteria of periprosthetic joint infection: a prospective study protocol to validate the feasibility of the 2018 new definition for Chinese patients

Background

Periprosthetic joint infection (PJI) is a challenging complication following total joint arthroplasty (TJA), and the diagnostic criteria remains controversial. The 2018 new definition proposed in May 2018 consists of new diagnostic criteria for PJI. We conducted a retrospective study and demonstrated that the new definition could improve the diagnostic efficiency in Chinese patients. However, missing data led to bias in the previous retrospective study. Therefore, this prospective study is designed to further validate the feasibility of 2018 new definition (and its modified version) for Chinese patients.

Methods/design

This is a single-centre, prospective diagnostic study with 1 year of follow-up. The patients enrolled in the trial will be divided into a PJI group and an Aseptic group based on the eligibility criteria. We will recruit at least 70 patients for each group from October 2019 to October 2020. Blood samples, synovial fluid samples and intraoperative variables of all the included patients will be collected to assess various indicators. We will integrate the results of the various tests and examine the diagnostic efficiency (sensitivity and specificity) of five diagnostic criteria.

Discussion

We design the prospective study in the hope of reducing the bias caused by missing data. Therefore, the prospective study will further support the conclusion of our preceding retrospective study. The results of this study will be submitted to a peer-reviewed journal for publication.

Conclusion

Through this prospective study, we will validate the feasibility of the 2018 new PJI definition (and its modified version) for Chinese patients and determine the optimal method of PJI diagnosis.

Trial registration

Chinese Clinical Trial Registry, ChiCTR1900025395. Registered on 25 August 2019.

New diagnostic tools for prosthetic joint infection

The diagnosis of peri-prosthetic bone and joint infections relies on converging information from clinical, laboratory and imaging assessments. Clinical findings alone may suffice: a sinus tract is a major criterion that establishes the diagnosis of infection. Identifying the causative organism is crucial and requires the early collection of high-quality samples from sites in contact with the prosthetic material. The bacteriological samples may be obtained by aspiration or open surgery. Imaging techniques have undergone remarkable improvements over the last two decades. Ultrasonography can be performed early and can be used to guide a needle biopsy if appropriate. Computed tomography or magnetic resonance imaging shows the extent of bone and/or soft-tissue involvement, provided effective artefact-suppression techniques are applied. Nuclear medicine methods have an undefined place in the diagnostic strategy and their possible role must be evaluated during a multidisciplinary discussion. The array of new laboratory methods introduced in recent years includes microbiological culture techniques, molecular biology tests, antigen and antibody assays and tests for immune markers in blood and/or joint fluid. When the first-line investigations fail to provide a definitive diagnosis, a multidisciplinary discussion at a referral centre for complex osteo-articular infections makes a major contribution to defining the subsequent diagnostic strategy. This lecture focusses on the following six questions: does the clinical assessment still have diagnostic relevance? What is the diagnostic contribution of imaging studies? Must the infection be documented pre-operatively and if so, how? Which microbiological techniques should be used? Which non-microbiological investigations help to diagnosis peri-prosthetic bone and joint infections? What role do referral centres for complex bone and joint infections play in the diagnostic strategy?

What Markers Best Guide the Timing of Reimplantation in Two-stage Exchange Arthroplasty for PJI? A Systematic Review and Meta-analysis

BACKGROUND

There is no consensus on the appropriate marker to use when deciding to perform reimplantation after two-stage exchange arthroplasty for periprosthetic joint infection (PJI).

QUESTIONS/PURPOSES

What tests provide acceptable diagnostic value to guide appropriate timing of reimplantation in two-stage exchange arthroplasty for PJI?

METHODS

A search of online databases (MEDLINE, EMBASE, OVID, and Cochrane database) was performed containing articles that provided sensitivity and specificity values for accuracy for predicting reimplantation of the hip and/or knee. Twelve articles were included for final analysis, which included data from 1047 patients. Data that described the diagnostic accuracy of markers for reimplantation were evaluated and categorized into four main entities according to diagnostic method (serologic, synovial, tissue, and diagnostic imaging). Twelve parameters were examined, including serum erythrocyte sedimentation (ESR) rate, serum C-reactive protein (CRP), serum white blood cell (WBC) count, synovial fluid Gram stain, synovial fluid culture, synovial fluid sonication culture, synovial fluid WBC, synovial fluid polymorphonucleocyte percentage (PMN%), tissue Gram stain, tissue culture, positron emission tomography scan, and leukocyte scan. Each of the included articles was independently analyzed for risk of bias and applicability by using QUADAS-2. Statistical heterogeneity was calculated by using the Cochran Q test, and an α of 0.10 was considered significant for heterogeneity.

RESULTS

Tissue culture (sensitivity 0.82 [0.72-0.90], specificity 0.91 [0.89-0.95], diagnostic odds ratio (DOR) 46.87 [95% confidence interval {CI}, 22.03-99.69], synovial fluid PMN% (sensitivity 0.77 [0.46-0.95], specificity 0.74 [0.67-0.81], DOR 11.27 [95% CI, 2.89-43.61]), and synovial fluid culture (sensitivity 0.64 [0.52-0.74], specificity 0.96 [0.93-0.98], DOR 27.07 [95% CI, 2.55-288.00]) showed relatively high diagnostic performance. Other parameters had poorer diagnostic accuracy: ESR (sensitivity 0.56 [0.40-0.72], specificity 0.60 [0.53-0.66], DOR 2.41 [95% CI, 0.60-9.72), CRP (sensitivity 0.53 [0.39-0.67], specificity 0.72 [0.66-0.78], DOR 2.25 [95% CI, 0.09-4.63), and synovial fluid WBC count (sensitivity 0.37 [0.19-0.58], specificity 0.49 [0.41-0.57], DOR 0.94 [95% CI, 0.06-14.74). However, interpretation is limited, because only two to three studies were available for each pooled analysis. Both risks of bias and applicability concerns were low in the four domains assessed in QUADAS-2.

CONCLUSIONS

This meta-analysis suggests that no single marker was superior to all the others, and none (when used alone) is likely sufficient to confirm control of infection after the first stage of a two-stage protocol for PJI. Therefore, the current approach using multiple tools rather than a single marker is essential. Additionally, further studies must be conducted so that pooled analysis can be performed using multiple studies to determine ideal markers for reimplantation.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Synovial Fluid Biomarkers for the Diagnosis of Periprosthetic Joint Infection: A Systematic Review and Meta-Analysis

BACKGROUND

The search for a single standard reference test for determining periprosthetic joint infection (PJI) through analysis of synovial fluid has yielded numerous biomarkers as potential candidates. The purpose of the present systematic review and meta-analysis was to evaluate the diagnostic accuracy of synovial fluid biomarkers and to determine which test has the highest diagnostic odds ratio (DOR) for the diagnosis of PJI.

METHODS

An online literature search of the MEDLINE, Embase, and Cochrane databases identified 33 articles reporting a total of 13 major parameters for diagnosing PJI through analysis of synovial fluid. Each of the included articles was independently analyzed for risk of bias and for concerns regarding applicability utilizing the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies-2) tool. The mada (meta-analysis of diagnostic accuracy) tool was used to generate forest plots for sensitivity, specificity, and the log of the DOR, as well as summary statistics.

RESULTS

In this analysis, 13 index tests (leukocyte count; measurement of the percentage of polymorphonucleocytes [PMN%] and the levels of C-reactive protein [CRP], α-defensin, leukocyte esterase [LE], interleukin [IL]-6, IL-8, IL-10, IL-1β, vascular endothelial growth factor [VEGF], and granulocyte-colony stimulating factor [G-CSF]; culture; and polymerase chain reaction [PCR] analysis) were evaluated on the basis of ≥2 articles. Of these tests, 8 (leukocyte count, PMN%, CRP, α-defensin, LE, IL-6, IL-8, and culture) were appropriate for pooled analysis. The overall sensitivity of these 8 markers was 0.85, and all but culture showed a sensitivity of ≥0.8. All markers showed a specificity of ≥0.9. Of the 8 tests, measurement of the α-defensin level showed the highest log DOR.

CONCLUSIONS

Synovial fluid leukocyte count, PMN%, CRP, α-defensin, LE, IL-6, and IL-8 all demonstrated high sensitivity for diagnosing PJI, with α-defensin being the best synovial marker based on the highest log DOR. However, other synovial fluid tests that demonstrate good diagnostic performance can also be used in combination for the diagnosis of PJI.

LEVEL OF EVIDENCE

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

How To Diagnose and Treat Infection in Total Ankle Arthroplasty

Periprosthetic infection after total ankle arthroplasty (TAA) is a serious complication, often requiring revision surgery, including revision arthroplasty, conversion to ankle arthrodesis, or even amputation. Risk factors for periprosthetic ankle infection include prior surgery at the site of infection, low functional preoperative score, diabetes, and wound healing problems. The clinical presentation of patients with periprosthetic ankle joint infection can be variable and dependent on infection manifestation: acute versus chronic. The initial evaluation in patients with suspected periprosthetic joint infections should include blood tests: C-reactive protein and erythrocyte sedimentation rate. Joint aspiration and synovial fluid analysis can help confirm suspected periprosthetic ankle infection.

[Aseptic loosening of total ankle replacement and conversion to ankle arthrodesis]

OBJECTIVE

To remove loosened prosthesis components, to perform augmentation, to address osseous defects, to perform neutrally aligned ankle arthrodesis, and to achieve postoperative pain relief.

INDICATIONS

Symptomatic, aseptic loosening of total ankle replacement (TAR) with/without substantial bone defect of the tibial and/or talar bone stock.

CONTRAINDICATIONS

General surgical or anesthesiological risks, periprosthetic infection, local or systemic infection, nonmanageable soft tissue problems.

SURGICAL TECHNIQUE

Removal of both prosthesis components using the previous incision (mostly using anterior ankle approach). Careful debridement of bone stock at the tibial and talar side. Osseous augmentation of defects using autologous or homologous cancellous bone, if needed, using structural allografts.

POSTOPERATIVE MANAGEMENT

A soft wound dressing is used. Thromboprophylaxis is recommended. Patient mobilization starts on postoperative day 1 with 15 kg partial weight bearing using a stabilizing walking boot or cast for 6-8 weeks. Following clinical and radiographic follow-up at 6 weeks, full weight bearing is initiated gradually after progressive osseous healing has been confirmed.

RESULTS

Between January 2007 and December 2012, ankle arthrodesis was performed in 9 patients with failed TAR (6 men and 3 women, mean age 56.4 ± 7.0 years, range 47.8-66.0 years). The mean time between the initial TAR and revision surgery was 4.5 ± 2.4 years (range 1.2-7.9 years). In one patient irrigation and debridement was performed due to superficial wound infection. Another patient had a delayed osseous healing 11 months after the revision surgery.

Diagnosis of infected total hip arthroplasty

Despite the battery of available tests, the diagnosis of periprosthetic joint infection (PJI) remains a challenge. A comprehensive medical history and physical examination with appropriate radiographs followed by erythrocyte sedimentation rate and serum C-reactive protein are the first-line screening test for patients with suspected hip PJI. The second line of investigation of patients with abnormal serology or a strong suspicion for PJI, is joint aspiration. Aspirates should be sent for assessment of white blood cell count, polymorphonuclear percentage, leukocyte esterase strip test, and microbiology. If the first attempt fails, the joint should be re-aspirated at a different time. The International Consensus recommends against infiltration of saline or other fluids into a "dry" joint. In patients not planned for surgery but need further evaluation for PJI, a nuclear imaging study may help. In others with a planned revision surgery, intraoperative samples for frozen section and culture study are the best measures available. Treatment strategies for PJI are well established in the literature. Poor surgical candidates receive oral suppressive antibiotic therapy alone. Acute PJI, presenting within 4 weeks of the index surgery, or as a result of bacteraemia, may be treated with irrigation and debridement and implant retention. Chronic PJI, occurring more than 4 weeks after initial surgery, is treated with 1-stage or 2-stage revision arthroplasty. In some persistent infections or patients who refuse to undergo revision surgery, salvage procedures may be needed.