Non-purulent low-grade infection as cause of pain following shoulder surgery: preliminary results

A Literature Review of Cutibacterium Acnes: From Skin Commensal to Pathogen in Shoulder Surgery

Cutibacterium acnes, previously known as Propionibacterium acnes, is a gram-positive rod in the pilosebaceous glands and commonly implicated in acne vulgaris. Its role in prosthetic joint infections, particularly in shoulder surgeries, has recently gained attention due to its prevalence around the shoulder girdle. This review collates evidence on the pathogenic role of C. acnes in shoulder surgeries, discussing preventive measures, risk factors, clinical presentation, investigation, and treatment strategies. C. acnes infections are complex, often presenting with non-specific symptoms and delayed diagnoses. Risk factors include male sex, presence of hair, shoulder steroid injections, and previous shoulder surgeries. Investigations such as inflammatory markers, synovial fluid analysis, diagnostic arthroscopy, tissue cultures, and advanced molecular techniques like next-generation sequencing and multiplex polymerase chain reaction are explored for their effectiveness in detecting C. acnes. Treatment strategies range from prolonged antibiotics and antibiotic spacers to single-stage and two-stage revision surgeries. Studies indicate that single-stage revision may provide better outcomes compared to two-stage revision. Effective management of C. acnes infections requires careful assessment, relevant investigations, and tailored treatment approaches. This review emphasizes the need for further research to address intraoperative contamination and to develop more efficient diagnostic and treatment methods.

The predictive value and reliability of ultrasound-guided synovial aspiration and biopsies for diagnosing periprosthetic shoulder infections

INTRODUCTION

Preoperative diagnosis of periprosthetic shoulder infections (PSI) is difficult. Infections are mostly caused by low virulence bacteria and patients do not show typical signs of infection. The aim of this study was to determine the diagnostic value and reliability of ultrasound-guided biopsies for cultures alone and in combination with multiplex polymerase chain reaction (mPCR), serum markers, and/or synovial markers for the preoperative diagnosis of PSI in patients undergoing revision shoulder surgery.

MATERIALS AND METHODS

A prospective explorative diagnostic cohort study was performed including 55 patients undergoing revision shoulder replacement surgery. A shoulder puncture was performed preoperatively before incision to collect synovial fluid for mPCR analysis and for measurement of interleukin-6, calprotectin, white blood cell count (WBC), and polymorphonuclear cells. Also prior to revision surgery, six ultrasound-guided synovial tissue biopsies were collected for culture and two for mPCR analysis. A blood sample was obtained to determine serum C-reactive protein, WBC, and erythrocyte sedimentation rate. Six routine care tissue biopsies were taken during revision surgery and served as reference standard. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV; the primary outcome measure), and accuracy were calculated for ultrasound-guided biopsies, blood and synovial markers, mPCR, and combinations thereof.

RESULTS

Routine tissue cultures were positive for infection in 24 patients. Cultures from ultrasound-guided biopsies diagnosed infection in 7 of these patients, yielding a sensitivity, specificity, PPV, NPV, and accuracy of 29.2%, 93.5%, 77.8%, 63.0%, and 65.6%, respectively. The best diagnostic value was found for the combination of ultrasound-guided biopsies for culture, synovial WBC, and calprotectin with a sensitivity of 69.2%, specificity of 80.0%, PPV of 69.2%, and NPV of 80.0%.

CONCLUSION

Ultrasound-guided biopsies for cultures alone and in combination with mPCR, and/or blood and/or synovial markers are not reliable enough to use in clinical practice for the preoperative diagnosis of PSI.

LEVEL OF EVIDENCE

Diagnostic study level II.

A High Rate of Bacteriologic Culture-Positive Findings Is Seen After Revision Rotator Cuff Surgery

Purpose

To determine the incidence of subclinical infections in patients undergoing revision arthroscopic rotator cuff repair and identify any risk factors for developing these infections.

Methods

Patients who underwent revision surgery by the senior author between January 2012 and December 2022 after a previous rotator cuff surgery were identified. All patients undergoing an open or arthroscopic revision of their previous rotator cuff surgery were included. Patients who had noted previous shoulder infections or had incomplete chart documentation were excluded. For each patient, demographic information, surgical information, and culture results were recorded.

Results

A total of 115 patients were identified. Thirty-nine were excluded due to incomplete chart documentation (35) or a history of infection (4); therefore, 22 patients (28.9%) had positive cultures (31 cultures in total). Seventeen patients had only Cutibacterium acnes identified. C acnes cultures turned positive on average 13.52 days after culture collection. There was no difference in infection incidence rates between isolated rotator cuff repair and rotator cuff repair plus additional surgeries (P = .88) or between initial arthroscopic versus open procedures (P = .83). None of the 12 identified risk factors, including age, sex, race, smoking history, previous corticosteroid injections, malnutrition, renal failure, liver failure, diabetes mellitus, immunocompromised status, intravenous drug use, and number of revisions, were correlated with the presence of a subclinical infection. Finally, 6 patients had control cultures taken. One culture (16.6%) was positive for C acnes, while this patient did not have a positive shoulder culture.

Conclusions

Subclinical shoulder infections can be present in more than one-quarter of patients undergoing revision after rotator cuff repair.

Level of Evidence

Level IV, diagnostic case series.

Reverse rhino sign as a radiological sign of low-grade infected reverse shoulder arthroplasty

INTRODUCTION

Low-grade infections following shoulder surgery are difficult to diagnose. Recently, curved-shaped bony spurs, further mentioned "reverse rhino signs" because of its shape, growing inferior on the glenoid were noticed on X-rays of patients with a reverse shoulder arthroplasty (RSA) and a Cutibacterium acnes (C. acnes) infection. This study aimed to determine the sensitivity and specificity of the reverse rhino sign as a radiological marker for detecting low-grade shoulder infections in RSA.

MATERIALS AND METHODS

A diagnostic study was performed including patients who underwent revision surgery of an RSA with perioperative cultures taken. Blinded radiographic evaluation was performed by two orthopedic surgeons for presence of rhino signs, humeral osteophytes, and notching. Efficacy measures of the reverse rhino sign for detecting low-grade infections were determined. Furthermore, results were stratified for notching and gender.

RESULTS

Thirty-two revised RSA patients had a low-grade infection and 36 had no infection. Seventeen (53%) patients with infection had a reverse rhino sign present, compared to 6 (17%) in the non-infection group. Sensitivity, specificity, positive and negative predictive value of the reverse rhino sign were, respectively, 53%, 83%, 74%, and 67%. These measures changed to 68%, 77%, 72%, and 74% for patients without notching and to 47%, 100%, 100%, and 8% for males.

CONCLUSION

In the absence of a reverse rhino sign in RSA patients, a low-grade shoulder infection is unlikely. Hence, the reverse rhino sign can be used to rule in a low-grade shoulder infection, especially in males and in the absence of notching. Low-grade infections should be considered in patients with unexplained persistent shoulder complaints after RSA placement, especially when a rhino sign is present. For these patients, we advise to perform mini-open biopsy for cultures.

LEVEL OF EVIDENCE

Diagnostic level IV.

Pre- and peroperative diagnosis of Cutibacterium acnes infections in shoulder surgery: A systematic review

BACKGROUND

Cutibacterium acnes is the most commonly detected pathogen during shoulder surgery. Lack of typical infection signs make Cutibacterium acnes infections difficult to diagnose. This systematic review aims to determine which pre- and peroperative diagnostic tools are most reliable to identify Cutibacterium acnes infections after shoulder surgery.

METHODS

PubMed/Embase were searched for diagnostic studies. Methodological quality of included studies was assessed using QUADAS-2. Forest plots summarized results (sensitivity and specificity) for each pre- and peroperative diagnostic tool.

RESULTS

Twenty-two studies were included, of which 8 described preoperative, 10 peroperative, and 4 both pre- and peroperative diagnostic tools. Quality of the studies varied widely. For preoperative tools, synovial calprotectin, interleukin-6, and combined interleukin-6/interleukin-2/tumor necrosis factor-α had the best efficacy measures. Pre-revision biopsies and arthroscopic tissue cultures were the best peroperative tools.

CONCLUSION

Despite a lack of evidence and the use of different Cutibacterium acnes infection criteria and reference standards, the use of combined interleukin-6/interleukin-2/tumor necrosis factor-α as preoperative and arthroscopic tissue cultures as peroperative diagnostic tool is for now recommended based on results and validity. More research should be performed to provide valid evidence on these tools. In order to do so, an internationally accepted definition of Cutibacterium acnes infections is essential.

LEVEL OF EVIDENCE

Systematic review.

Cutibacterium acnes infections in revision surgery for persistent shoulder complaints: a retrospective cohort study

INTRODUCTION

Low-grade Cutibacterium acnes (C. acnes) infections after shoulder surgery usually result in unexplained complaints. The absence of clinical signs of infection makes the incidence unclear and underreported. This study aimed to determine the incidence of C. acnes infections in patients with artificial material and unexplained persistent shoulder complaints. We hypothesized that the incidence of C. acnes infections would be higher in patients with artificial material. Risk factors and associations between culture time and contaminations/infections were also assessed.

MATERIALS AND METHODS

This retrospective cohort study included patients with and without artificial material undergoing revision shoulder surgery for persistent complaints after primary surgery and the suspicion of a low-grade infection. Three-six cultures were taken in all patients. C. acnes infection incidence was determined and logistic regression analysis was performed to identify risk factors. The association between time to culture growth and infections/contaminations was evaluated using Kaplan-Meier analysis and log-rank test.

RESULTS

26/61 (42.6%) patients with and 14/33 (42.2%) without material had a C. acnes infection. Age (OR 0.959; 95% CI 0.914-1.000) and BMI (OR 0.884; 95% CI 0.787-0.977) were risk factors. Time to C. acnes culture positivity was not different between infections and contaminations.

CONCLUSION

The incidence of C. acnes infections was 42.6% in patients with artificial material and 42.2% in patients without artificial material. Younger age and lower BMI are risk factors. Low-grade C. acnes infections should be considered in patients with unexplained persistent complaints following shoulder surgery.

Capsular needle biopsy as a pre-operative diagnostic test for peri-prosthetic shoulder infection

BACKGROUND

Establishing the diagnosis of peri-prosthetic shoulder infection prior to revision shoulder arthroplasty can be difficult. The objectives of the present study were (i) to describe the technique of fluoroscopic capsular needle biopsy for the diagnosis of peri-prosthetic shoulder infection and (ii) to determine the feasibility and preliminary accuracy of the test in a pilot sample of patients undergoing revision shoulder arthroplasty.

METHODS

Eighteen patients, comprising eight females and nine males with a mean age of 61 years (range 37 years to 81 years) underwent capsular needle biopsy during the work-up of suspected chronic arthroplasty-related glenohumeral infection. Intra-operative tissue samples were taken from a minimum of three regions of the joint capsule during revision surgery. Standard serum indices were obtained.

RESULTS

Of 17 patients with possible infection, five had confirmed culture positive infections based on intra-operative biopsies. Of these five patients, four (80%) had positive cultures from fluoroscopic capsular needle biopsy, with matching cultures. There were no complications. No culture-positive patients had elevated serum indices for infection.

CONCLUSIONS

The technique for fluoroscopic capsular needle biopsy appears to be feasible and the preliminary results for this technique appear to be promising, with a sensitivity of 80% and a specificity of 100%.Level of evidence: Level II: diagnostic test.

Shoulder Joint Infections with Negative Culture Results: Clinical Characteristics and Treatment Outcomes

Background

The incidence of septic arthritis of the shoulder joint is increasing as the population ages. The prevalence of shoulder infection is also increasing because of the growing use of arthroscopy and expansion of procedures in the shoulder. However, cultures do not always identify all microorganisms, even in symptomatic patients. The incidence of negative cultures ranges from 0% to 25%. Few studies have reported clinical features and treatment outcomes of culture-negative shoulder infections. This cohort study addresses culture-negative shoulder joint infections in nonarthroplasty patients. This study aimed to compare clinical characteristics and treatment outcomes of patients with culture-negative results to those with culture-positive results. Our hypothesis was that culture-negative infections would have more favorable outcomes than culture-positive infections.

Methods

We retrospectively reviewed data of 36 patients (17 culture-negative and 19 culture-positive) with shoulder infections between June 2004 and March 2015. The minimum follow-up duration was 1.2 years (mean, 5 ± 3.8 years; range, 1.2-11 years). We assessed preoperative demographic data and characteristics, laboratory markers, imaging and functional scores, intraoperative findings, and postoperative findings of both groups.

Results

Culture-negative patients (17/36, 47.2%) had a significantly lower occurrence of repeated surgical debridement (culture-negative vs. culture-positive: 1.2 ± 0.4 vs. 2.4 ± 1.7, p = 0.002) without osteomyelitis. In the multiple logistic regression analysis, the presence of osteomyelitis [odds ratio (OR) = 9.7, 95% confidence interval (CI): 1.0-91.8, p=0.04)] and the number of surgical debridements (OR = 5.3, 95% CI: 1.3-21.6, p=0.02) were significantly associated with culture-positive infections.

Conclusions

Culture-negative infections without osteomyelitis are less severe than culture-positive infections. Culture-negative infections can be controlled more easily and are not necessarily a negative prognostic factor for shoulder joint infections.

Polymicrobial anaerobic infection with a deep abscess in the supraspinous fossa following a subacromial corticosteroid injection

In September 2015, a male aged 61 years with poorly controlled diabetes (his only medical problem) had left shoulder surgery that included an arthroscopic acromioplasty with debridement of suture material from a rotator cuff repair done 10 years prior. A subacromial corticosteroid injection was given 7 months later for pain and reduced motion. Three weeks later a fulminate infection was evident. Cultures grew Propionibacterium acnes. Treatment included two arthroscopic debridement surgeries and 8 weeks of intravenous antibiotics (primarily daptomycin). Eight weeks after the cessation of the antibiotics, purulence recurred and tissue cultures then grew Staphylococcus epidermidis. Several additional surgeries were needed to control the infection. We failed to recognise that an abscess that extended from the subacromial space across the entire supraspinous fossa. We report this case to alert clinicians that a seemingly innocuous subacromial corticosteroid injection can lead to an atypical infection and also extend into the supraspinous fossa.

Bilateral Neck Pyomyositis Caused by Staphylococcus capitis and Staphylococcus saccharolyticus in a Diabetic Adult

We report a case of pyomyositis of the paraspinal neck muscles caused by two coagulase-negative staphylococci: Staphylococcus capitis and Staphylococcus saccharolyticus. Inflammation in the spermatic cords was an additional feature of this infection. Treatment with six weeks of first-generation cephalosporin therapy resulted in complete clinical and radiological resolution.

Propionibacterium acnes infection after shoulder surgery

Propionibacterium acnes has been implicated as a cause of infection following shoulder surgery, may occur up to 2 years after the index operation and has been shown to be responsible for up to 56% of shoulder infections after orthopedic implant. Male patients within the population undergoing shoulder surgery are particularly at risk, especially if their shoulder surgery involved prosthesis or was posttraumatic. P. acnes infection can be difficult to diagnose clinically and laboratory techniques require prolonged and specialized cultures. Usual inflammatory markers are not raised in infection with this low virulence organism. Delayed diagnosis with P. acnes infection can result in significant morbidity prior to prosthesis failure. Early diagnosis of P. acnes infection and appropriate treatment can improve clinical outcomes. It is important to be aware of P. acnes infection in shoulder surgery, to evaluate risk factors, to recognize the signs of P. acnes infection, and to promptly initiate treatment. The signs and symptoms of P. acnes infection are described and discussed. Data were collected from PubMed™, Web of Science, and the NICE Evidence Healthcare Databases - AMED (Ovid), BNI (Ovid), CINAHL (EBSCO), Embase (Ovid), HMIC: DH-Data and Kings Fund (Ovid), Medline (Ovid), and PsycINFO (Ovid). The search terms used were "P. acnes," "infection," "shoulder," and "surgery." In this review, we summarize the current understanding of the prevention and management of P. acnes infection following shoulder surgery.