Proceedings from the 2018 International Consensus Meeting on Orthopedic Infections: evaluation of periprosthetic shoulder infection

Does hydrogen peroxide application to the dermis following surgical incision affect Cutibacterium acnes cultures in total shoulder arthroplasty in male patients? A randomized controlled trial

BACKGROUND

Periprosthetic joint infections occur in 1%-4% of primary total shoulder arthroplasties (TSAs). Cutibacterium acnes is the most commonly implicated organism and has been shown to persist in the dermis despite use of preoperative antibiotics and standard skin preparations. Studies have shown decreased rates of cultures positive for C acnes with use of preoperative benzoyl peroxide or hydrogen peroxide (H2O2), but even with this positive deep cultures remain common. We sought to determine whether an additional application of H2O2 directly to the dermis following skin incision would further decrease deep culture positivity rates.

METHODS

We performed a randomized controlled trial comparing tissue culture results in primary TSA in patients who received a standard skin preparation with H2O2, ethanol, and ChloraPrep (CareFusion, Leawood, KS, USA) vs. an additional application of H2O2 to the dermis immediately after skin incision. Given the sexual dimorphism seen in the shoulder microbiome regarding C acnes colonization rates, only male patients were included. Bivariable and multivariable analyses were performed to compare rates of positive cultures based on demographic and surgical factors.

RESULTS

Dermal cultures were found to be positive for C acnes at similar rates between the experimental and control cohorts for the initial (22% vs. 28%, P = .600) and final (61% vs. 50%, P > .999) dermal swabs. On bivariable analysis, the rate of positive deep cultures for C acnes was lower in the experimental group, but this difference was not statistically significant (28% vs. 44%, P = .130). However, patients who underwent anatomic TSA were found to have a significantly greater rate of deep cultures positive for C acnes (57% vs. 28%, P = .048); when controlling for this on multivariable analysis, the experimental cohort was found to be associated with significantly lower odds of having positive deep cultures (odds ratio, 0.37 [95% confidence interval, 0.16-0.90], P = .023). There were no wound complications in either cohort.

CONCLUSIONS

An additional H2O2 application directly to the dermis following skin incision resulted in a small but statistically significant decrease in the odds of having deep cultures positive for C acnes without any obvious adverse effects on wound healing. Given its cost-effectiveness, use of a post-incisional dermal decontamination protocol may be considered as an adjuvant to preoperative use of benzoyl peroxide or H2O2 to decrease C acnes contamination.

Two-Stage Exchange Arthroplasty for Periprosthetic Reverse Shoulder Arthroplasty Infection Provides Comparable Functional Outcomes to Primary Reverse Shoulder Arthroplasty

This study aimed to compare functional outcomes after two-stage revision reverse shoulder arthroplasty (RSA) for periprosthetic joint infection (PJI) with the results of primary RSA. Patients affected by PJI and treated by means of two-stage revision RSA were 1:1 matched with a group of patients who were treated electively with RSA without developing any complications. Out of 1477 RSAs performed between 2009 and 2021, 16 patients developed a PJI. Each matched cohort comprised 16 patients (3 females, 13 males). The mean age was 69.13 ± 5.43 years old in the PJI group and 70.28 ± 5.04 (p = 0.543) in the matched cohort. The mean follow-up was 41.23 ± 26.9 months in the PJI group and 28.5 ± 20.2 (p = 0.142) in the matched group. Only one patient showed recurrent PJI five years after revision RSA. Comparison between the PJI patients and matched patients did not show any significant differences at the latest follow-up, nor for subjective shoulder value (SSV) (p = 0.101) or Constant score (p = 0.134). Two-stage exchange RSA for PJI allows for appropriate control of the disease and good functional outcomes. Comparison with an age- and sex-matched cohort of uninfected patients showed no significant differences, thus confirming the idea that revision surgeries may lead to satisfactory functional outcomes, as expected after primary surgery.

Preventing and Treating Infection in Reverse Total Shoulder Arthroplasty

PURPOSE OF REVIEW

Periprosthetic infection after shoulder arthroplasty is relatively uncommon though associated with severe long-term morbidity when encountered. The purpose of the review is to summarize the recent literature regarding the definition, clinical evaluation, prevention, and management of prosthetic joint infection after reverse shoulder arthroplasty.

RECENT FINDINGS

The landmark report generated at the 2018 International Consensus Meeting on Musculoskeletal Infection has provided a framework for diagnosis, prevention, and management of periprosthetic infections after shoulder arthroplasty. Shoulder specific literature with validated interventions to reduce prosthetic joint infection is limited; however existing literature from retrospective studies and from total hip and knee arthroplasty allows us to make relative guidelines. One and two-stage revisions seem to demonstrate similar outcomes; however, no controlled comparative studies exist limiting the ability to make definitive recommendations between the two options. We report on recent literature regarding the current diagnostic, preventative, and treatment options for periprosthetic infection after shoulder arthroplasty. Much of the literature does not distinguish between anatomic and reverse shoulder arthroplasty, and further high-level shoulder specific studies are needed to answer questions generated from this review.

Cutibacterium positive cultures in total joint arthroplasty: a comparison of the hip, knee, and shoulder

PURPOSE

Cutibacterium spp. (formerly Propionibacterium) is a slow growing, Gram-positive, anaerobic bacteria and is an emerging clinical entity in prosthetic joint infection (PJI). This study compares the presentation, surgical management, and post-operative antibiotic therapy of patients with positive intraoperative cultures during revision total joint arthroplasty (TJA) of the hip, knee, and shoulder.

METHODS

This was a retrospective cohort study of patients from 2014 to 2020 of 57 revision TJAs (27 total hip arthroplasty (THA), 17 total shoulder arthroplasty (TSA), and 13 total knee arthroplasty (TKA)) with intraoperative cultures positive for Cutibacterium at a tertiary academic centre. Patient demographics, pre-operative labs, radiographs, and aspirate results were collected. Intraoperative data was reviewed. Post-operative antibiotic therapy and repeat infections were recorded. Data was compared with univariate analyses.

RESULTS

There was no significant difference in pre-operative lab values between the cohorts. All cohorts had > 58% radiographic lucency. Revision TSA patients had significantly fewer pre-operative aspirates. Six patients undergoing revision THA, three TKA and one TSA had a repeat infection requiring further surgery. Four in the THA cohort and one in the TKA cohort with repeat infections did not receive prolonged antibiotic therapy.

CONCLUSION

Cutibacterium is an infectious agent that can present in an indolent fashion after TJA. It commonly causes progressive radiographic lucency. The workup and post-operative management differs in the hip, knee, and shoulder, which is likely due to existing literature guiding physician practice. In all joints, Cutibacterium is a virulent pathogen that can cause repeat infections requiring surgical treatment.

The Challenge of Periprosthetic Joint Infection Diagnosis: From Current Methods to Emerging Biomarkers

Due to the increase in the life span and mobility at older ages, the number of implanted prosthetic joints is constantly increasing. However, the number of periprosthetic joint infections (PJIs), one of the most severe complications after total joint arthroplasty, also shows an increasing trend. PJI has an incidence of 1-2% in the case of primary arthroplasties and up to 4% in the case of revision operations. The development of efficient protocols for managing periprosthetic infections can lead to the establishment of preventive measures and effective diagnostic methods based on the results obtained after the laboratory tests. In this review, we will briefly present the current methods used in PJI diagnosis and the current and emerging synovial biomarkers used for the prognosis, prophylaxis, and early diagnosis of periprosthetic infections. We will discuss treatment failure that may result from patient factors, microbiological factors, or factors related to errors during diagnosis.

[Shoulder periprosthetic infections-what to do? : Diagnosis and treatment]

Treatment of an infected shoulder prosthesis differs significantly from other joint infections because of the unique microbiome, dominated by Cutibacterium acnes. The cause of an infection, its time of onset, the bacterial spectrum and comorbidities have to be considered for evaluation and treatment. The diagnostic workup is sometimes complex, and the recognition of a chronic and low-grade infection is often difficult because typical clinical and laboratory markers may be normal. Treatment is surgical; the therapeutic spectrum ranges from arthroscopic irrigation and open debridement with the exchange of components to one- and two-stage revisions using antibiotic-loaded spacers. Early detection and a targeted, appropriate therapy are crucial to avoid extensive soft tissue and bone damage.

Prosthetic joint infections of the shoulder: A review of the recent literature

Introduction

Shoulder arthroplasty is a common treatment for shoulder arthritis. Prosthetic joint infection of the shoulder (PJIS) is a debilitating complication to the patient and the healthcare system. Incidence of infection is 0.98-5% for primary arthroplasty. The mean hospital cost for two-stage revision was approximately $35,824. The aim of this paper is to review the recent literature and collate the latest evidence to aid diagnosis and treatment of this serious complication.

Methods

A literature review was performed using PubMed and Google Scholar databases. A search strategy was adopted using the keywords: 'infection' AND 'shoulder arthroplasty' OR 'total shoulder arthroplasty'OR 'TSA' OR 'reverse shoulder arthroplasty' OR 'RSA' OR 'rTSA'. This initial search resulted in 349 articles. A PRISMA flowchart process was followed. Duplicates were removed, screening was performed and the resulting full texts were analysed and further excluded, leaving 46 articles suitable for inclusion. A PICO search strategy was also used.

Results and interpretation

Risk factors for PJIS include procedure type, trauma indications and patient factors.The organism commonly isolated is Cutebacterium acnes, which makes diagnosis challenging due to its indolent nature. Investigations include biochemical tests, synovial aspirate, tissue cultures and radiological examinations.Treatment depends on the depth of the infection and the patient requirements. Medical treatment with antibiotics to local debridement, cement spacer and revision arthroplasty have all been described in the literature. A multidisciplinary decision is made on the microbiological evidence and patient factors.

Conclusion

PJIS is a rare but potentially devastating complication of shoulder arthroplasty and diagnosis is often challenging. There has been much research performed recently, providing more evidence on how to optimise management.

Diagnostic Performance of Advanced Metal Artifact Reduction MRI for Periprosthetic Shoulder Infection

BACKGROUND

The diagnosis of periprosthetic shoulder infection (PSI) in patients with a painful arthroplasty is challenging. Magnetic resonance imaging (MRI) may be helpful, but shoulder implant-induced metal artifacts degrade conventional MRI. Advanced metal artifact reduction (MARS) improves the visibility of periprosthetic bone and soft tissues. The purpose of our study was to determine the reliability, repeatability, and diagnostic performance of advanced MARS-MRI findings for diagnosing PSI.

METHODS

Between January 2015 and December 2019, we enrolled consecutive patients suspected of having PSI at our academic hospital. All 89 participants had at least 1-year clinical follow-up and underwent standardized clinical, radiographic, and laboratory evaluations and advanced MARS-MRI. Two fellowship-trained musculoskeletal radiologists retrospectively evaluated the advanced MARS-MRI studies for findings associated with PSI in a blinded and independent fashion. Both readers repeated their evaluations after a 2-month interval. Interreader reliability and intrareader repeatability were assessed with κ coefficients. The diagnostic performance of advanced MARS-MRI for PSI was quantified using sensitivity, specificity, and the area under the receiver operating characteristic curve (AUC). When applying the International Consensus Meeting (ICM) 2018 criteria, of the 89 participants, 22 (25%) were deemed as being infected and 67 (75%) were classified as being not infected (unlikely to have PSA and not requiring a surgical procedure during 1-year follow-up).

RESULTS

The interreader reliability and intrareader repeatability of advanced MARS-MRI findings, including lymphadenopathy, joint effusion, synovitis, extra-articular fluid collection, a sinus tract, rotator cuff muscle edema, and periprosthetic bone resorption, were good (κ = 0.61 to 0.80) to excellent (κ > 0.80). Lymphadenopathy, complex joint effusion, and edematous synovitis had sensitivities of >85%, specificities of >90%, odds ratios of >3.6, and AUC values of >0.90 for diagnosing PSI. The presence of all 3 findings together yielded a PSI probability of >99%, per logistic regression analysis.

CONCLUSIONS

Our study shows the clinical utility of advanced MARS-MRI for diagnosing PSI when using the ICM 2018 criteria as the reference standard. Although the reliability and diagnostic accuracy were high, these conclusions are based on our specific advanced MARS-MRI protocol interpreted by experienced musculoskeletal radiologists. Investigations with larger sample sizes are needed to confirm these results.

LEVEL OF EVIDENCE

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

Outcomes of instability after reverse shoulder arthroplasty: reoperation and persistent instability are common

HYPOTHESIS

Although risk factors for instability after reverse shoulder arthroplasty (RSA) have been extensively studied, the outcomes of patients who experience instability are unknown. The purpose of this study was to evaluate functional outcomes in patients with instability after RSA.

METHODS

We retrospectively identified patients with instability after RSA with a minimum of 2 years' follow-up from an institutional database. Baseline data were recorded, and all patients we contacted to obtain clinical outcome scores. Patients who required revision surgery and those treated successfully with closed reduction were compared.

RESULTS

Fifty patients were included. Of these patients, 40 (80%) required revision surgery whereas 10 (20%) were treated successfully with closed reduction. At an average follow-up of 63.7 months (range, 24-123 months), outcome scores did not differ between groups. Patients who required revision surgery were more likely to have undergone previous shoulder surgery, prior to their index arthroplasty (P = .031). Seventeen patients (42.5%) reported recurrent instability following revision surgery, and 14 (35.0%) required additional revision surgery. Ultimately, stability was never achieved in 7 of 50 patients (14%) after their index instability event.

CONCLUSION

Although instability after RSA can commonly be corrected with reasonable functional results, multiple procedures may be needed and some patients may experience persistent instability.

Management of periprosthetic infection after reverse shoulder arthroplasty

BACKGROUND

Periprosthetic shoulder infection (PSI) remains a devastating complication after reverse shoulder arthroplasty (RSA). Currently, scientific data related to the management of PSI are limited, and the optimal strategy and related clinical outcomes remain unclear. Guidelines from the Infectious Diseases Society of America for the management of periprosthetic joint infection are mainly based on data from patients after hip and knee arthroplasty. The aim of this study was to evaluate whether these guidelines are also valid for patients with PSI after RSA. In addition, the functional outcome according to the surgical intervention was assessed.

METHODS

An RSA database was retrospectively reviewed to identify infections after primary and revision RSAs, diagnosed between 2004 and 2018. Data collected included age, sex, indication for RSA, causative pathogen, surgical and antimicrobial treatment, functional outcome, and recurrence.

RESULTS

Thirty-six patients with a PSI were identified. Surgical treatment was subdivided into débridement and implant retention (DAIR) (n = 6, 17%); 1-stage revision (n = 1, 3%); 2-stage revision (n = 16, 44%); multiple-stage revision (>2 stages) (n = 7, 19%); definitive spacer implantation (n = 2, 6%); and resection arthroplasty (n = 4, 11%). The most common causative pathogens were Staphylococcus epidermidis (n = 11, 31%) and Cutibacterium acnes (n = 9, 25%). Recurrence was diagnosed in 4 patients (11%), all of whom were initially treated with a DAIR approach. The median follow-up period was 36 months (range, 24-132 months).

CONCLUSION

PSI is typically caused by low-virulence pathogens, which often are diagnosed with a delay, resulting in chronic infection at the time of surgery. Our results indicate that treatment of patients with chronic PSI with DAIR has a high recurrence rate. In addition, implant exchange (ie, 1- and 2-stage exchange) does not compromise the functional result as compared with implant retention. Thus, patients with chronic PSI should be treated with implant exchange. Future research should further clarify which surgical strategy (ie, 1-stage vs. 2-stage exchange) has a better outcome overall.

The utility and cost of atypical cultures in revision shoulder arthroplasty

BACKGROUND

At the time of revision shoulder arthroplasty, it is common practice to take cultures to evaluate for prosthetic joint infection even when an alternative cause of failure has been identified. Although isolation of fungal or acid-fast organisms is rare, it remains common practice to send all specimens for aerobic, anaerobic, and atypical (fungal and acid-fast) cultures. We hypothesize that the rate of positive atypical cultures at the time of revision shoulder arthroplasty is very low and routine use imposes a considerable financial burden on the health care system.

METHODS

A retrospective review of all revision shoulder arthroplasties performed between January 1, 2010, and December 31, 2019, at our institution was performed. Patients with a hemiarthroplasty, total shoulder arthroplasty, reverse shoulder arthroplasty, or pre-existing antibiotic spacer who underwent revision to hemiarthroplasty, total shoulder arthroplasty, reverse shoulder arthroplasty, antibiotic spacer, or resection arthroplasty were included. Electronic patient charts were reviewed to gather patient, surgical, and culture data. An analysis of the hospital billing charges associated with each culture was performed using our hospital billing database and the current procedural terminology (CPT) codes for aerobic, anaerobic, fungal, and acid-fast cultures. A secondary outcome analysis was performed to identify factors associated with positive cultures.

RESULTS

A total of 237 revision shoulder arthroplasties performed on 189 patients were analyzed. Cultures were sent on 158 of 237 (66.7%) surgeries with an average of 2.2 specimens per surgery. A total of 341 aerobic, 331 anaerobic, 187 fungal, and 174 acid-fast cultures were collected. Positive cultures were found in 52 of 341 (15.2%) aerobic cultures and 36 of 331 (10.9%) anaerobic cultures. The most commonly isolated organism was Cutibacterium acnes (42.2%), followed by methicillin-resistant Staphylococcus aureus (15.6%), coagulase-negative Staphylococcus species (13.3%), and methicillin-sensitive S. aureus (12.2%). There were zero positive fungal or acid-fast cultures in our series. The total billing charges for aerobic, anaerobic, fungal, and acid-fast cultures over the study period were $77,748, $23,832, $8,789, and $106,662, respectively, with atypical cultures accounting for 53.2% of the total charges for all cultures. For a single sample sent for all 4 culture types, atypical cultures account for 69% of the total amount charged.

CONCLUSION

Isolation of fungal or acid-fast organisms at the time of revision shoulder arthroplasty is rare and imposes a considerable financial burden when these atypical cultures are sent on a routine basis. The collection of fungal and acid-fast cultures should be reserved for patients in whom risk factors for these atypical organisms have been identified.

Validation of new shoulder periprosthetic joint infection criteria

BACKGROUND

A periprosthetic joint infection (PJI) in the shoulder can be difficult to diagnose. Many variables have been used to determine a PJI. Recently, the 2018 International Consensus Meeting (ICM) on orthopedic infections gave new criteria to help identify PJI in the shoulder. With the new criteria (major and minor), the PJI definition can be categorized into definite, probable, possible, and unlikely. This study was conducted to assess the new criteria for a series of consecutive first stage revision shoulder arthroplasty cases.

METHODS

All patients undergoing a first stage revision shoulder arthroplasty using a prosthesis made of antibiotic-loaded acrylic cement (PROSTALAC) spacer from 2016 through 2019 were evaluated retrospectively. All cases were performed by a single surgeon. Each case was reviewed using the 2018 shoulder ICM diagnostic criteria. Secondary factors evaluated were type of organism identified, accuracy of minor criteria, and frozen vs. permanent section accuracy.

RESULTS

A total of 87 first-stage revision arthroplasty cases were reviewed. Based on the 2018 ICM criteria, there were 20 definite (30.0%), 19 probable (21.8%), 6 possible (6.9%), and 42 unlikely (48.3%) infections. Cutibacterium acnes was the most common infectious organism overall (77.3% of culture positive cases) and was present in 39.1% of cases overall. Ten patients (25.6%) grew multiple organisms. Thirty-one patients (35.6%) had a loose humeral stem, with 23 of those patients (74.2%) having a definite or probable infection (odds ratio [OR] 7.2, 95% confidence interval [CI] 2.67-19.37, P = .0001). Eleven patients (91.7%) with an elevated intraoperative synovial neutrophil cell count had a definite or probable infection. Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) was elevated in patients with a definite or probable infection (OR 9.4, 95% CI 2.47-35.62, P = .0010, and OR 7.7, 95% CI 2.29-25.56, P = .0009), respectively. Discordant results between frozen and permanent sections were found in 4 patients (4.6%).

CONCLUSION

The 2018 ICM shoulder infection criteria gave a new scoring system to diagnose PJI. C acnes was the most common infectious organism identified. Patients who had a loose humeral stem, elevated ESR, or elevated CRP were more likely to have either a definite or probable PJI. Frozen sections were able to accurately identify definite infections. Unexpected wound drainage and positive preoperative cultures were low-yield criteria in this series. More research into determining periprosthetic shoulder infection is needed to help identify which patients are more likely to have an infection.

Creation of a Custom-Length, Humeral Antibiotic Cement Spacer for Use in Treatment of Shoulder Periprosthetic Joint Infection

Periprosthetic joint infection of the shoulder is a challenging clinical situation to manage owing to the fastidious organisms often present and delayed clinical presentation. While several treatment options have been described, the mainstay of treatment remains a staged revision with the use of a humeral antibiotic cement spacer. Such spacers are commercially available or can be made by hand. When an extended humeral osteotomy is required to remove a well-fixed long stem humeral component, it may be advantageous to place an antibiotic spacer with a stem length approximately as long as the hardware being removed. This technique demonstrates creation of a custom length, humeral antibiotic cement spacer for use in treatment of shoulder periprosthetic joint infection.

Editorial Commentary: Are Serum Inflammatory Markers Useful Diagnostic Tools in the Shoulder?

Serum inflammatory markers are commonly used to evaluate for the presence of surgical-site infection or periprosthetic joint infections following orthopaedic surgery. However, data on the utility of these tests following shoulder surgery are more limited. Worse diagnostic performance is seen in the shoulder when compared with use of these tests in the evaluation of hip and knee infections, likely due to the low virulence of the commonly cultured shoulder organisms, and the normalization of these serum markers following shoulder surgery is less well defined when compared with the hip and knee literature. A better understanding of the behavior of these serum inflammatory markers in the shoulder may enhance the utility of these tests in the diagnosis and management of infection following elective shoulder surgery.

Periprosthetic Infection After Reverse Shoulder Arthroplasty: a Review

PURPOSE OF REVIEW

Periprosthetic infection is a relatively rare but potentially devastating complication after shoulder arthroplasty. The purpose of this article is to review the incidence, diagnosis, prevention, and management of periprosthetic infections after reverse shoulder arthroplasty, with a focus on literature published within the last 5 years.

RECENT FINDINGS

The 2018 International Consensus Meeting on Musculoskeletal Infection provides us with a framework for the diagnosis and management of periprosthetic infections after shoulder arthroplasty. Reverse shoulder arthroplasty has a higher reported rate of infection compared with anatomic total shoulder arthroplasty. Our current diagnostic tests do not appear to be as sensitive when compared with the hip and knee literature. Similar success has been reported with single and two-stage revision protocols, although prospective comparative data are lacking. The significance of unexpected positive cultures during revision arthroplasty remains unclear. We report current diagnostic and therapeutic options for periprosthetic infection after reverse shoulder arthroplasty. Much of the current literature does not distinguish between anatomic and reverse shoulder arthroplasty. Further high-level studies are warranted to refine these definitions and guide management.

An Evolution of Shoulder Periprosthetic Infections Management: MicroDTTect, Bioactive Glass and Tantalum Cones Employment

Periprosthetic joint infections of the shoulder (PJIS) are the major cause for revision within the first two post-operative years, and are challenging both to diagnose and treat. Success depends on early identification of microorganisms, appropriate surgical procedures and efficient antibiotic administration. The peculiar microbiology of the shoulder may render the criteria for hip/knee PJI management inappropriate. In addition, later cases with clinically subtle signs often present diagnostic challenges. In recent years, specific issues of PJIS have been managed through the use of new instruments, such as MicroDTTect in pathogen detection and Bioactive Glass and tantalum cones in humeral bone loss. In the literature to date, no reports have been found that discuss the application in shoulder revisions and infections. The early identification of the microorganisms that cause infection may help improve both treatment strategies and the efficacy of therapy. MicroDTTect proved to be more efficient than swab collection for bacterial identification in orthopedic surgery, thus reducing analysis costs. The increasing number of shoulder arthroplasties is associated with an increase in the number of revisions. In cases of massive metaphyseal humeral bone loss, several techniques have been described; no reports have been reported regarding tantalum in humeral bone loss management. In some cases the tantalum cones required adaptation for femoral diaphysis in the augmentation of the humerus metaphysis and bone loss management improvement. Obtaining stable osseointegration of prosthetic implants is one of the greatest issues in orthopedic surgery, and even more crucial in revisions. Bioactive glasses demonstrated good regenerative and osseointegration properties, and an excellent candidate as a bone graft, scaffold and antibiotics deliverer. The Bioactive glasses were used to increase prosthesis-bone interface stability and fill bone defects in PJIS revision surgeries, contributing to the prevention of re-infection. Longer-term follow-up will be necessary to determine if construction durability is improved in the long term.

Preoperative Skin Cultures Predict Periprosthetic Infections in Revised Shoulder Arthroplasties: A Preliminary Report

Current approaches do not provide a practical method for the accurate prediction of a Cutibacterium periprosthetic joint infection (PJI) in failed arthroplasties. Thus, surgeons revising failed arthroplasties must decide whether to exchange the implants and to institute antibiotic treatment without knowing the results of cultures of deep specimens obtained at the revision procedure. This study tests the hypothesis that the results of preoperative culture specimens of the skin surface obtained in the clinic can predict the presence of culture-positive Cutibacterium PJIs.

METHODS

Revision shoulder arthroplasties performed between October 3, 2017, and February 4, 2020, that had both preoperative clinic culture specimens and surgical culture specimens were included in this analysis. Culture results were assigned a value from 0 to 4. The percentage of the total skin bacterial load contributed by Cutibacterium (Cutibacterium percentage) was determined. To reduce concern about contamination, a robust criterion for culture-positive Cutibacterium PJI was applied: ≥2 surgical specimens with a Cutibacterium value of ≥1. The predictive values for a culture-positive Cutibacterium PJI were determined for a clinic skin culture Cutibacterium value of >1 and a clinic skin percentage of Cutibacterium of ≥75%.

RESULTS

Eighteen cases met the inclusion criteria; of these, 7 (6 male patients) met our criterion for a culture-positive Cutibacterium PJI. For all patients, a preoperative clinic skin Cutibacterium value of >1 predicted the presence of a culture-positive Cutibacterium PJI with an accuracy of 89%, and a clinic skin Cutibacterium percentage of ≥75% predicted the presence of a culture-positive Cutibacterium PJI with an accuracy of 94%. For male patients, a preoperative clinic skin Cutibacterium value of >1 predicted the presence of a culture-positive Cutibacterium PJI with an accuracy of 91%, and a clinic skin Cutibacterium percentage of ≥75% predicted the presence of a culture-positive Cutibacterium PJI with an accuracy of 100%.

CONCLUSIONS

A simple culture specimen of the unprepared skin surface obtained in a clinic prior to revision shoulder arthroplasty may provide valuable assistance to surgeons planning a revision arthroplasty.

LEVEL OF EVIDENCE

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

Arthroscopic Evaluation and Treatment of Complications That Arise Following Prosthetic Shoulder Arthroplasty

Arthroscopy may be used to diagnose symptomatic glenoid loosening following anatomic total shoulder arthroplasty (aTSA), and arthroscopic glenoid component removal may suffice as treatment for some patients. Arthroscopy may be used to diagnose shoulder prosthetic joint infection (PJI) following aTSA and reverse shoulder arthroplasty (RSA). Tissues are biopsied from multiple sites within the joint and the subdeltoid or subacromial space, and they are cultured for a minimum of 14 days. Postoperative adhesions arising after prosthetic shoulder arthroplasty (PSA) may be released arthroscopically. However, other problems contributing to shoulder stiffness such as component malpositioning or shoulder PJI require additional intervention. Arthroscopy may be used to repair select rotator cuff tears that arise acutely following aTSA, but chronic attritional tears do not heal after repair; therefore, revision to RSA often is needed. Many complications following PSA, such as infection, fixed instability, humeral component loosening, and major humeral or glenoid bone loss, are not adequately treated using arthroscopic techniques. However, arthroscopy following PSA may help to diagnose and treat other complications, even as the precise indications following aTSA and RSA remain unclear.

The role of implant sonication in the diagnosis of periprosthetic shoulder infection

BACKGROUND

The aim of this study was to investigate the validity of implant sonication fluid cultures in the diagnosis of shoulder periprosthetic joint infection (PJI) compared with tissue culture.

METHODS

This was a retrospective case-control study analyzing all patients who underwent a revision surgery for any kind of suspected septic or aseptic event due to failed shoulder arthroplasty at our institution between July 2014 and December 2018. The diagnostic validity of implant sonication was analyzed on the basis of the last proposed definition criteria of the International Consensus Meeting and compared with standard tissue cultures.

RESULTS

Of the 72 patients, a total of 28 (38.9%) were classified as infected. Of the 28 infected patients, 20 (71.4%) had an identified organism by tissue cultures, and Cutibacterium acnes was the most commonly isolated pathogen. The sensitivities of sonicate fluid (≥50 CFU/mL) and periprosthetic tissue culture for the diagnosis of periprosthetic shoulder infection were 36% and 61% (P = .016), and the specificities were 97.7% and 100% (P > .99), respectively. If no cutoff value was used in sonication culture, the sensitivity increased to 75% whereas the specificity dropped to 82%. Although there was no significant difference in sensitivity between tissue culture and the no-cutoff sonication fluid culture (61% vs. 75%, P = .125), the specificity of tissue culture was significantly higher (100% vs. 82%, P = .01).

CONCLUSION

Tissue culture showed a higher sensitivity and specificity than implant sonication in the diagnosis of shoulder PJI and should remain the gold standard for microbiological diagnosis of shoulder PJI.