Diagnosing a periprosthetic shoulder infection: A systematic review

Evaluation of Risk Factors for Periprosthetic Joint Infection Following Reverse Shoulder Arthroplasty: A Multivariate Analysis Study

Background/Objectives: Reverse shoulder arthroplasty (RSA) has been widely used for the treatment of shoulder pathologies, particularly rotator cuff tear arthropathy. Currently, it is also increasingly performed for different indications. Like in any arthroplasty procedure, periprosthetic joint infection (PJI) is one of the most concerning complications and may have devastating outcomes. This study aimed to identify risk factors for PJI following RSA. Methods: This retrospective case-control study was conducted with patients who underwent RSA during the study period. Based on PJI occurrence during the follow-up period, patients were divided into two groups: Group I (no infection) and Group II (infection). The relationship between numerous clinical variables and PJI was tested. All variables were initially evaluated through univariate analysis between the two groups, and variables showing significant differences between the two study groups were subjected to multivariate logistic regression analysis to determine independent risk factors. Results: The study included 302 patients, with a mean age of 69.6 ± 10.1 years and a mean follow-up duration of 59.8 ± 24.7 months. During the follow-up period, PJI was not detected in 289 patients (95.7%) (Group I), while 13 patients (4.3%) developed PJI (Group II). Univariate analysis revealed a significant association between preoperative C-reactive protein (CRP) value (p = 0.001) and preoperative diabetes history (p = 0.007) with PJI. Multivariate logistic regression analysis, including these two variables, showed that diabetes was an independent risk factor for PJI development (p = 0.01, odds ratio = 4.85). Preoperative CRP elevation was not observed as an independent risk factor. Conclusions: This study demonstrated a significant association between high preoperative CRP levels and diabetes with PJI. Additionally, the presence of diabetes was identified as an independent risk factor for infection, with a 4.85-fold higher risk of PJI development in patients with a history of diabetes.

Assessment of periprosthetic joint infection in revision shoulder arthroplasty

BACKGROUND

In those undergoing revision shoulder arthroplasty, the diagnosis of periprosthetic joint infection (PJI) remains challenging with many clinical and diagnostic variables being considered. The purpose of the study was to evaluate the predictive value of pertinent preoperative and intraoperative factors associated with eventual PJI as determined by the 2018 International Consensus Meeting (ICM) criteria.

MATERIALS AND METHODS

All revision shoulder arthroplasties performed at a single tertiary referral medical center from July 2013 to January 2024 were retrospectively analyzed. Patients were evaluated as definite, probable, possible or unlikely infection according to the 2018 ICM criteria.

RESULTS

Overall, 386 patients underwent revision shoulder arthroplasty, with a mean age of 70 ± 10 years, and 51.3% were female. According to the ICM criteria, 38 patients (9.8%) had definite PJI, 22 had probable PJI (5.7%), 23 had possible PJI (6.0%), and 302 were unlikely to have PJI (78.2%). The majority of patients (n = 71.8%) diagnosed with definitive PJI had 1 major criterion for diagnosis, with all 3 criteria only occurring in 5.1% of these patients. Patients with definite PJI met a mean of 4.6 ± 3.3 minor criteria, and those with probable PJI met a mean of 4.6 ± 2.9 minor criteria. Elevated erythrocyte sedimentation rate (ESR) had the highest positive predictive value (PPV; 75.0%) of preoperative laboratory test values collected, whereas elevated synovial white blood cell count and polymorphonuclear leukocyte percentage each had a PPV of 80%.

DISCUSSION

The majority of revision shoulder arthroplasties are performed for patients who are unlikely to have a PJI, with less than 10% meeting ICM criteria for definite PJI. Most patients meeting criteria for definite PJI met only 1 major criterion, underscoring the importance of minor criteria in diagnosis. Serum ESR and C-reactive proteinCRP had moderate sensitivity and specificity for PJI, and aspiration may still have value in the standard diagnostic workup of shoulder PJI.

Synovial fluid leukocytes as diagnostic marker in periprosthetic shoulder infection

Background

Limited data exist regarding the diagnostic accuracy of synovial fluid leukocyte count (SFLC) in diagnosing periprosthetic shoulder infection (PSI). The main objective of this study was to determine the diagnostic value of leukocyte count at a common threshold of 3 cells/nL and the optimal cut-off value.

Methods

Patients who underwent shoulder arthroplasty revision surgery and aspiration with SFLC between 2012 and 2023 were retrospectively included. The International Consensus Meeting 2018 definition was used to characterize infection status for SFLC threshold and synovial fluid neutrophil percentage (SFNP). Sensitivity and specificity were presented using cross tabulation. The area under the curve was calculated, and the optimal cut-off was determined using maximized Youden Index.

Results

35 cases with an average age of 71 years (43% male) were included in our study. At a threshold of 3 cells/nL, SFLC showed a sensitivity of 70% and specificity of 83%. The corresponding positive and negative predictive values (PPV and NPV) were 89% and 59%, respectively. We found the optimal cut-off for our cohort at 4.7 cells/nL, increasing specificity to 92% while maintaining sensitivity at 70% (PPV = 94%, NPV = 61%). SFNP at a cut-off of 80% demonstrated 50% sensitivity and 91% specificity, with corresponding PPV and NPV of 92% and 48%, respectively. The optimum threshold for SFNP was 54%, which had a sensitivity of 77% and a specificity of 64%, as well as a PPV of 81%, and NPV of 58%. The area under the curve was 0.72 for SFLC and 0.74 for SFNP. Sonication detected pathogens in 63% of cases, while 57% of all cases showed positive tissue cultures and 43% positive aspirate cultures. Especially, the most frequently found microorganism, Cutibacterium acnes, was detected less often in aspirate culture.

Conclusions

SFLC shows good specificity but moderate sensitivity for diagnosing PSI when using a threshold of 4.7 cells/nL. Therefore, it can serve as a confirmatory test for diagnosing PSI but not for ruling out infection.

Shoulder Periprosthetic Joint Infection: Principles of Prevention, Diagnosis, and Treatment

➢ Shoulder periprosthetic joint infection (PJI) is a potentially devastating complication after arthroplasty and is projected to rise with increasing numbers of performed arthroplasties, particularly reverse shoulder arthroplasties.➢ Important considerations for the diagnosis and treatment of shoulder PJI include age, sex, implant type, primary compared with revision shoulder surgery, comorbidities, and medications (i.e., corticosteroids and disease-modifying antirheumatic drugs). ➢ Diagnosis and management are unique compared with lower-extremity PJI due to the role of lower-virulence organisms in shoulder PJI, specifically Cutibacterium acnes.➢ Treatment pathways depend on chronicity of infection, culture data, and implant type, and exist on a spectrum from irrigation and debridement to multistage revision with temporary antibiotic spacer placement followed by definitive revision arthroplasty.

Cutibacterium acnes in Shoulder Surgery: Is It a Significant Risk Factor for Postoperative Infection?

Cutibacterium acnes, a commensal, lipophilic, anaerobic Gram-positive bacterium, is well known for its potential to cause infections, particularly in the field of orthopedics, notably in the shoulder. However, its indolent strain nature presents challenges in the diagnosis of the bacterium using clinical, laboratory, and culture-based methods. There are controversies surrounding its actual threat as an infection-causing agent, leading to an incomplete consensus on treatment strategies after the infection. Furthermore, research is ongoing to explore preventive procedures before the onset of infection. This review aimed to comprehensively explore the diagnosis and treatment of C. acnes and determine whether it is a risk factor for shoulder joint infections.

Primary Closure of External Fixator Pin Sites Is Safe After Orthopaedic Trauma Surgery

OBJECTIVES

To determine if rates of pin site infection and surgical site infection among patients managed with primary closure after external fixator removal were similar to those allowed to heal secondarily.

METHODS

DESIGN

Retrospective cohort.

SETTING

Urban/Suburban Academic Level I Trauma Center.

PATIENT SELECTION CRITERIA

Patients who had received a lower extremity external fixator for provisional management before definitive fixation of lower extremity fractures were included with pin site wounds closed primarily or allowed to heal by secondary intention.

OUTCOME MEASURES AND COMPARISONS

The rate of pin tract infection and surgical site infection following primary closure of external fixator pin sites relative to patients whose pin sites were allowed to heal through secondary intention.

RESULTS

In total, 256 patients were evaluated: 143 patients (406 pin sites) in the primary closure group and 113 patients (340 in sites) in the secondary closure group. The average age was 49 ± 16 years. Sixty-five percent of included patients were male. There was no difference in pin tract infections between cohorts (primary = 0.5%, secondary = 1.5%, P = 0.26). External fixator duration in the primary closure group was 11.5 ± 8.4 days and 13.0 ± 8.1 days in the secondary closure group (P = 0.15). There was a greater rate of surgical site infections in the secondary intention cohort (15.9% vs. 7.7%, P = 0.047).

CONCLUSIONS

There was no difference in pin site infection rate after primary pin site closure relative to patients who were allowed to heal through secondary intention. Furthermore, there was a lower rate of surgical site infection after primary closure. These results challenge the dogma of secondary closure for ex fix pin sites, suggesting that debridement and primary closure is a safe option for management of external fixator pin sites and may impart benefit in decreasing infection risk.

LEVEL OF EVIDENCE

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

Efficacy of a Novel Intraoperative Surgical Irrigant in Preventing Periprosthetic Joint Infections in Primary Knee, Hip, and Shoulder Arthroplasties: A Retrospective Analysis

OBJECTIVE

Primary joint arthroplasty (JA) is one of the most common operating room (OR) procedures, with knee and hip arthroplasties being listed in the top five most frequent OR procedures and while not as common, shoulder arthroplasties are increasing at greater rates than knee and hip arthroplasties. Periprosthetic joint/shoulder infections (PJI/PSI) are a devastating complication of primary JAs with infection prevention deemed as the single most important strategy in combating them. The objective of this study was to retrospectively evaluate the efficacy of XPERIENCE® Advanced Surgical Irrigation (XP) in preventing PJI following primary joint arthroplasty.

METHODS

This is a retrospective study of primary knee, hip and shoulder arthroplasties that were performed by multiple orthopedic surgeons at a single hospital setting. XPERIENCE was used as an intraoperative surgical irrigant either solely, or with other intraoperative practices for prevention of infection. Incidence of acute PJI occurring within 90 days of index surgery were retrospectively collated.

RESULTS

Four hundred and twenty-three (423) primary joint replacement surgeries treated intraoperatively with XP, were evaluated for acute PJI incidence. Retrospective evaluations determined that 95% of the subjects had at least one risk factor predisposing them to PJI. There were zero PJIs diagnosed in the knee and hip arthroplasty cohorts and zero PSIs diagnosed in the shoulder arthroplasty cohorts.

CONCLUSION

The absence of PJI/PSI diagnoses in the JA cohorts treated intraoperatively with XP indicates that it could be an efficacious antimicrobial irrigant in preventing PJI, and warrants being evaluated in prospective, randomized controlled clinical trials as the sole intraoperative irrigant, as well as in combination with the other intraoperative infection prevention regimens evaluated in this retrospective study.

Quantitative Real-Time Polymerase Chain Reaction May Serve as a Useful Adjunct to Conventional Culture in The Detection of Cutibacterium acnes in the Glenohumeral Joint: A Study of 100 Consecutive Patients

Objectives

Synovial fluid or tissue culture is the current gold standard for diagnosis of infection, but Cutibacterium acnes (C. acnes) is a frequent cause of shoulder PJI and is a notoriously fastidious organism. The purpose of this study was to compare quantitative real-time polymerase chain reaction (qRT-PCR) to standard culture as a more rapid, sensitive means of identifying C. acnes from the glenohumeral joint. We hypothesized that qRT-PCR would be more effective than standard culture at identifying C. acnes and would have greater sensitivity and specificity for detecting infection.

Methods

This was a prospective observational study with 100 consecutive patients undergoing arthroscopic or open shoulder surgery with known positive and negative controls. Intraoperatively, synovial fluid and tissue was obtained for C. acnes qRT-PCR and results were blinded to the gold standard microbiology cultures.

Results

Clinical review demonstrated 3 patients (3%) with positive cultures, none of which were positive for C. acnes. Of the samples tested by the C. acnes qRT-PCR standard curve, 12.2% of tissue samples and 4.5% of fluid samples were positive. Culture sensitivity was 60.0%, specificity was 100.0%, PPV was 100.0%, and NPV was 97.9%. C. acnes qRT-PCR standard curve sensitivity, specificity, PPV, and NPV was 60.0%, 90.3%, 25.0%, and 97.7% respectively for tissue specimens and 0%, 95.2%, 0%, and 95.2% respectively, for fluid specimens. For combination of culture and tissue qRT-PCR, the sensitivity, specificity, PPV and NPV was 100%, 90.3%, 35.7%, and 100%, respectively.

Conclusion

We report that qRT-PCR for C. acnes identified the organism more frequently than conventional culture. While these findings demonstrate the potential utility of qRT-PCR, the likelihood of false positive results of qRT-PCR should be considered. Thus, qRT-PCR may be useful as an adjuvant to current gold standard workup of synovial fluid or tissue culture for the diagnosis of infection.

Preoperative prophylactic antibiotics administration does not influence culture yield in revision shoulder arthroplasty

BACKGROUND

The importance of administrating prophylactic antibiotics prior to a surgical procedure is well established. Given the difficulty in diagnosing shoulder periprosthetic infections, which are more indolent in nature, some advocate holding prophylactic antibiotics prior to obtaining cultures as there is a concern antibiotics may lead to a false negative culture result. The purpose of this study is to determine whether administration of antibiotics prior to obtaining cultures in revision shoulder arthroplasty influences culture yield.

METHODS

This was a retrospective analysis of revision shoulder arthroplasty cases performed at a single institution between 2015 and 2021. During the study period, each surgeon had a standardized protocol that dictated whether antibiotics were given or held prior to each revision surgery. Each case was categorized into either a Preculture antibiotic group, if antibiotics were administered prior to incision, or a Postculture antibiotic group if antibiotics were administered after incision and obtaining cultures. The International Consensus Meeting (ICM) scoring criteria provided by the Musculoskeletal Infection Society was used to categorize the probability of periprosthetic joint infection for each case. Culture positivity was calculated as the ratio of positive cultures and total number of cultures obtained.

RESULTS

One hundred twenty-four patients met inclusion criteria. There were 48 patients in the Preculture group and 76 patients in the Postculture group. No significant difference in patient demographics or ICM criteria (P = .09) was observed between the 2 groups. With regard to culture positivity, there was no difference between the Preculture antibiotic group and the Postculture antibiotic group (16% vs. 15%, P = .82, confidence interval = 8%-25% vs. 10%-20%, respectively).

CONCLUSION

In the setting of revision shoulder arthroplasty, timing of antibiotic administration did not significantly influence culture yield. This study supports the use of prophylactic antibiotics prior to obtaining cultures in revision shoulder arthroplasty.

Evaluation of the Painful Total Shoulder Arthroplasty

Despite the overall success of anatomic and reverse total shoulder arthroplasties (aTSA and rTSA), some patients continue to have or develop pain postoperatively. As the number of shoulder arthroplasties continues to increase in the United States, it is important that surgeons are able to recognize, diagnose, and treat the various pathologies. Some painful etiologies are specific to either aTSA or rTSA, and others can occur with both implant types. Infections, stiffness, neurologic syndromes, polyethylene wear, aseptic implant loosening, and metal allergies occur, regardless of implant choice. However, after an aTSA, subscapularis repair failure, superior rotator cuff tear, and joint overstuffing can result in shoulder pain. After a rTSA, specific causes of postoperative pain include instability, scapular notching, acromial or scapular spine fractures, subcoracoid pain, and neurologic injury. Regardless of the diagnosis, the surgeon must be methodical in the evaluation and, when appropriate, use blood work, advanced imaging studies, joint aspirations, shoulder arthroscopy, and nerve studies. Once diagnosed, appropriate treatment should be undertaken to resolve the cause of the pain or at least minimize the effect of the pain on the patient's outcome.

Immuno-Modulatory Effects of Intervertebral Disc Cells

Low back pain is a highly prevalent, chronic, and costly medical condition predominantly triggered by intervertebral disc degeneration (IDD). IDD is often caused by structural and biochemical changes in intervertebral discs (IVD) that prompt a pathologic shift from an anabolic to catabolic state, affecting extracellular matrix (ECM) production, enzyme generation, cytokine and chemokine production, neurotrophic and angiogenic factor production. The IVD is an immune-privileged organ. However, during degeneration immune cells and inflammatory factors can infiltrate through defects in the cartilage endplate and annulus fibrosus fissures, further accelerating the catabolic environment. Remarkably, though, catabolic ECM disruption also occurs in the absence of immune cell infiltration, largely due to native disc cell production of catabolic enzymes and cytokines. An unbalanced metabolism could be induced by many different factors, including a harsh microenvironment, biomechanical cues, genetics, and infection. The complex, multifactorial nature of IDD brings the challenge of identifying key factors which initiate the degenerative cascade, eventually leading to back pain. These factors are often investigated through methods including animal models, 3D cell culture, bioreactors, and computational models. However, the crosstalk between the IVD, immune system, and shifted metabolism is frequently misconstrued, often with the assumption that the presence of cytokines and chemokines is synonymous to inflammation or an immune response, which is not true for the intact disc. Therefore, this review will tackle immunomodulatory and IVD cell roles in IDD, clarifying the differences between cellular involvements and implications for therapeutic development and assessing models used to explore inflammatory or catabolic IVD environments.

Antibiotic Therapy for Prosthetic Joint Infections: An Overview

Prosthetic joint infection (PJI) is a severe complication after arthroplasty. Its management combines surgical intervention, whose type depends on the clinical situation, and prolonged high-dose antibiotics adapted to the responsible microorganism(s) and the patient. Antibiotics are only one part of the therapeutic regimen and are closely related to the surgical strategy. Their efficacy depends to a large extent on the choice and quality of the surgical procedure, and the quality of the microbiological diagnosis. Although guidelines have been published, many aspects of antibiotic therapy remain poorly established. Choosing the optimal agent(s) is one aspect, with others being optimization of drugs' pharmacokinetic/pharmacodynamic parameters, the choice of administration route, use of monotherapy or combination regimens, therapeutic drug-monitoring and patient education to improve compliance and tolerance. Herein, we address PJI management based on recent literature data, guidelines and the experience of our referral center for complex bone-and-joint infections.

Defining a Synovial Fluid White Blood Cell Count Threshold to Predict Periprosthetic Infection after Shoulder Arthroplasty

BACKGROUND

The diagnosis of periprosthetic shoulder infection (PSI) requires a thorough diagnostic workup. Synovial fluid aspiration has been proven to be a reliable tool in the diagnosis of joint infections of the lower extremity, but shoulder specific data is limited. This study defines a threshold for synovial fluid white blood cell count (WBC) and assesses the reliability of microbiological cultures.

METHODS

Retrospective study of preoperative and intraoperative fluid aspiration of 31 patients who underwent a revision of a shoulder arthroplasty (15 with PSI defined by IDSA criteria, 16 without infection). The threshold for WBC was calculated by ROC/AUC analysis.

RESULTS

WBC was significantly higher in patients with PSI than in other patients. A threshold of 2800 leucocytes/mm3 showed a sensitivity of 87% and a specificity of 88% (AUROC 0.92). Microbiological cultures showed a sensitivity of 76% and a specificity of 100%.

CONCLUSIONS

A threshold of 2800 leucocytes/mm3 in synovial fluid can be recommended to predict PSI. Microbiological culture has an excellent specificity and allows for targeted antibiotic therapy. Joint aspiration presents an important pillar to diagnose PSI.