Incidence and predictors of positive intraoperative cultures in primary shoulder arthroplasty following prior ipsilateral shoulder surgery

Are high cutibacterium bacterial loads at the time of revision shoulder arthroplasty associated with more severe clinical signs or symptoms or increased risk of recurrent periprosthetic joint infection?

PURPOSE

Cutibacterium is commonly isolated from deep tissue samples taken at the time of revision shoulder arthroplasty, but the significance of these positive cultures is debated, and the impact of increasing bacterial loads on clinical outcomes is unclear. The objectives of this study were to (1) identify factors independently associated with high bacterial loads, and (2) compare patient-reported outcomes (PROs) and revision rates in patients found to have high Cutibacterium loads.

MATERIALS AND METHODS

Male patients undergoing single stage exchange with a minimum 2-year follow-up were included. Culture data were semi-quantitatively scored with the total Cutibacterium score (TShCuS). Two groups were compared: patients with a High Cutibacterium Load (HCL) group and those with Low Cutibacterium Load (LCL) group. PROs and revision rates were compared, and a multivariable analysis was conducted.

RESULTS

Of 68 male patients that underwent revision shoulder arthroplasty, 29 (42.6%) met the inclusion criteria for the HCL group, while 27 patients (39.7%) were in the LCL group. Mean follow-up was 4.7 ± 3 years. Patients with intraoperative humeral loosening had an 18.4 times increased risk of having high Cutibacterium loads (95% CI 2.1-154.4, p < 0.001). There were no significant differences in PROs or re-revision rates between the HCL and LCL groups.

CONCLUSIONS

Intraoperative humeral loosening was independently associated with high Cutibacterium loads found at the time of revision shoulder arthroplasty. Male patients with high bacterial loads treated with complete single stage exchange and antibiotics had patient-reported outcomes similar to those of patients with minimal to no load.

LEVEL OF EVIDENCE

III.

A systematic review of distinction of colonization and infection in studies that address Cutibacterium acnes and shoulder surgery

BACKGROUND

After shoulder surgery, infection is often diagnosed in the absence of an inflammatory host response (purulence, sepsis). In the absence of inflammation, the more appropriate diagnoses may be colonization or contamination. We reviewed the available data regarding culture of Cutibacterium acnes during primary and revision shoulder surgery and asked; 1) what is the prevalence of air, skin, and deep tissue colonization? 2) How often is an inflammatory host response associated with diagnosis of postoperative shoulder infection diagnosed on the basis of culture of C. acnes? 3) Is there any relation between culture of C. acnes and outcomes of shoulder surgery?

METHODS

Three databases were searched for studies that address C. acnes and colonization or infection related to shoulder surgery. We analyzed data from 80 studies addressing the rates of C. acnes colonization/infection in patients undergoing shoulder surgery, evidence of an inflammatory host response, and relationship of C. acnes culture to surgery outcomes.

RESULTS

C. acnes is often cultured in the air in the operating room (mean 10%), the skin before preparation (mean 47%), and deep tissue in primary shoulder arthroplasty (mean 29%), arthroscopy (mean 27%), and other shoulder surgery (mean 21%). C. acnes was cultured from a mean of 39% of deep tissue samples during revision arthroplasty. C. acnes was believed to be the causative organism of a high percentage of the infections diagnosed after surgery, 39% in primary shoulder arthroplasties, 53% in revisions, 55% in arthroscopic surgeries, and 44% in a mixture of shoulder surgeries. Infection was nearly always diagnosed in the absence of an inflammatory host response. Documented purulence and sepsis were not specifically ascribed to C. acnes (rather than more virulent organisms such as S. aureus). Diagnosis of infection, or unexpected positive culture, with C. acnes during shoulder surgery is associated with outcomes comparable to shoulders with no bacterial growth.

CONCLUSIONS

The evidence to date supports conceptualization of C. acnes as a common commensal (colonization), and perhaps a frequent contaminant, and an uncommon cause of an inflammatory host response (infection). This is supported by the observations that 1) unexpected positive culture for C. acnes is not associated with adverse outcomes after shoulder surgery, and 2) diagnosed infection with C. acnes is associated with outcomes comparable to noninfected revision shoulder arthroplasty. We speculate that diagnosis of C. acnes infection might represent an attempt to account for unexplained discomfort, incapability or stiffness after technically sound shoulder surgery. If so, the hypothesis that stiffness and pain are host responses to C. acnes needs better experimental support.

Outcomes following revision reverse shoulder arthroplasty for infection

BACKGROUND

In comparison to primary reverse shoulder arthroplasty (RSA) procedures, revision arthroplasty can be a longer and more complex procedure leading to an increased risk of complications. The reported rates of infection in primary RSA range from 1% to 19% and the cost impact on patients and health care systems is significant, leading to multiple revision surgeries. The purpose of this study was to evaluate the postoperative outcomes, complications, and revision rates for revision reverse shoulder arthroplasty (rRSA) due to infection compared with rRSA for noninfectious causes.

METHODS

Patients who underwent rRSA between 2009 and 2020 by a single fellowship-trained orthopedic surgeon at a single institution were retrospectively identified through a prospectively collected database. Patients were separated into 2 cohorts based on revision diagnosis: (1) rRSA due to infection (rRSAi) and (2) rRSA due to noninfectious causes (rRSAn). Patient-reported outcome scores (PROs), including the Simple Shoulder Test, Constant score, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form score, University of California-Los Angeles shoulder score, Shoulder Arthroplasty Smart score, and active range of motion (ROM) were collected preoperatively and at a minimum 1-year follow-up. Postoperative complications and revision rates were also collected.

RESULTS

A total of 93 patients (n = 19 rRSAi group, n = 74 rRSAn group) with a mean age of 68 years were included in this analysis. All baseline demographics were comparable between groups. No significant differences were found in preoperative or postoperative PROs and ROM between the 2 groups. Postoperative complication rates and revision rates were comparable between the groups.

CONCLUSION

RSA due to infection results in similar patient-reported outcome scores, range of motion, and revision rates when compared to rRSA for noninfectious causes. Our results suggest that despite the unique challenges associated with rRSA for infection, patient outcomes do not differ from cases attributed to noninfectious causes. More efforts are warranted to further validate and contextualize these findings, considering the protentional influence of patient-specific and implant-specific factors.

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.

Anatomic Shoulder Arthroplasty in the Setting of Concurrent or Prior Rotator Cuff Repair: A Systematic Review

Background

Reverse total shoulder arthroplasty (RSA) is the gold standard in management of osteoarthritis (OA) in the setting of rotator cuff pathology. However, there are significant complications associated with the procedure. An alternative option in the setting of a deficient rotator cuff may be to perform a repair prior to or concurrently with an anatomic total shoulder arthroplasty (aTSA).

Methods

A systematic review was performed utilizing Preferred Reporting Items for Systematic Meta-Analyses (PRISMA) guidelines to evaluate outcomes in aTSA with concomitant or prior rotator cuff repair (RCR). Key outcomes were complication rate and subjective outcome scores.

Results

Seven studies were included in the review. One study found a higher rate of total adverse events in the prior repair group (17% vs 7%, P = .01) while others found no significant difference. There was a nonstatistically significant increase in revision rates among patients with larger tears at time of repair. Prior repair groups were associated with a higher rate of re-tear in one study (13% vs 1%, P = .014). Concomitant repair was associated with a higher rate of loosening. In patients with prior repair, there was no statistical difference in strength, range of motion (ROM), simple shoulder test (SST), Single Assessment Numeric Evaluation (SANE), American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form (ASES), and visual analogue scale (VAS). In patients with concurrent repair, one study demonstrated a less drastic improvement in Hospital for Special Surgery (HSS) in "moderate" repairs as opposed to "good" repairs.

Conclusions

Anatomic TSA is an appropriate treatment for glenohumeral OA in patients with a prior successful RCR and in younger patients with concurrent repair of small or medium tears.

Level of Evidence

Level III.

An evidence-based approach to managing unexpected positive cultures in shoulder arthroplasty

BACKGROUND

Unexpected positive cultures (UPCs) are very commonly found during shoulder arthroplasty when surgeons send intraoperative cultures to rule out periprosthetic joint infection (PJI) without clinical or radiographic signs of infection. Cutibacterium acnes is thought to be the most common bacteria cultured in this setting; however, the implications of an unexpected positive result are neither well defined nor agreed upon within the literature. The current review evaluates the incidence of UPCs and C acnes in reverse total arthroplasty; the clinical significance, if any, of these cultures; and various prognostic factors that may affect UPC incidence or recovery following PJI.

METHODS

A systematic review was performed with PRISMA guidelines using PubMed, CINAHL, and Scopus databases. Inclusion criteria included studies published from January 1, 2000, to May 20, 2021, that specifically reported on UPCs, native or revision shoulder surgery, and any study that directly addressed one of our 6 proposed clinical questions. Two independent investigators initially screened 267 articles for further evaluation. Data on study design, UPC rate/speciation, UPC risk factors, and UPC outcomes were analyzed and described.

RESULTS

A total of 22 studies met the inclusion criteria for this study. There was a pooled rate of 27.5% (653/2373) deep UPC specimen positivity, and C acnes represented 76.4% (499/653) of these positive specimens. Inanimate specimen positivity was reported at a pooled rate of 20.1% (29/144) across 3 studies. Male patients were more likely to have a UPC; however, the significance of prior surgery, surgical approach, and type of surgery conflicted across multiple articles. Patient-reported outcomes and reoperation rates did not differ between positive-UPC and negative-UPC patients. The utilization of antibiotics and treatment regimen varied across studies; however, the reinfection rates following surgery did not statistically differ based on the inclusion of antibiotics.

CONCLUSION

UPCs are a frequent finding during shoulder surgery and C acnes represents the highest percentage of cultured bacteria. Various preoperative risk factors, surgical techniques, and postoperative treatment regimens did not significantly affect the incidence of UPCs as well as the clinical outcomes for UPC vs. non-UPC patients. A standardized protocol for treatment and follow-up would decrease physician uncertainty when faced with a UPC from shoulder surgery. Given the results of this review, shoulder surgeons can consider not drastically altering the postoperative clinical course in the setting of UPC with no other evidence of PJI.

Hsu JE, Bumgarner RE, Bourassa LA, Budge MD, Duquin TR, Garrigues GE, Green A, Iannotti JP, Khazzam MS, Koh JL, Matsen FA, Namdari S, Nicholson TA, Richter SS, Sabesan VJ, Virk MS, Whitson AJ, Yian EH, Ricchetti ET. What do positive and negative Cutibacterium culture results in periprosthetic shoulder infection mean? A multi-institutional control study

BACKGROUND

Deep tissue culture specimens obtained at the time of revision shoulder arthroplasty are commonly positive for Cutibacterium. Clinical interpretation of positive cultures can be difficult. This was a multi-institutional study evaluating the accuracy of cultures for Cutibacterium using positive control (PC) and negative control (NC) samples. The relationship between time to culture positivity and strength of culture positivity was also studied.

METHODS

Eleven different institutions were each sent 12 blinded samples (10 PC and 2 NC samples). The 10 PC samples included 2 sets of 5 different dilutions of a Cutibacterium isolate from a failed total shoulder arthroplasty with a probable periprosthetic infection. At each institution, the samples were handled as if they were received from the operating room. Specimen growth, time to culture positivity, and strength of culture positivity (based on semiquantitative assessment) were reported.

RESULTS

A total of 110 PC samples and 22 NC samples were tested. One hundred percent of specimens at the 4 highest dilutions were positive for Cutibacterium. At the lowest dilution, 91% of samples showed positive findings. Cutibacterium grew in 14% of NC samples. Cutibacterium grew in PC samples at an average of 4.0 ± 1.3 days, and all of these samples showed growth within 7 days. The time to positivity was significantly shorter (P < .001) and the strength of positivity was significantly higher (P < .001) in true-positive cultures compared with false-positive cultures.

CONCLUSIONS

This multi-institutional study suggests that different institutions may report highly consistent rates of culture positivity for revision shoulder arthroplasty samples with higher bacterial loads. In contrast, with lower bacterial loads, the results are somewhat less consistent. Clinicians should consider using a shorter time to positivity and a higher strength of positivity as adjuncts in determining whether a tissue culture sample is a true positive.

Factors associated with failure of surgical revision and IV antibiotics to resolve Cutibacterium periprosthetic infection of the shoulder

PURPOSE

Cutibacterium is the most common organism causing shoulder periprosthetic infection (PJI). While most shoulder PJIs are well treated by prosthesis exchange and antibiotics, in some cases this treatment fails to resolve the infection. The factors associated with these failures have not been previously identified. The aim of this study was to identify the characteristics of patients with failure of treatment for PJI.

METHODS

Thirty-five patients suspected of having Cutibacterium PJI had revision arthroplasty with single-stage implant exchange followed by intravenous antibiotics. The characteristics of those with ≥ two positive cultures at revision surgery were compared to those who did not. The characteristics of those patients having a re-revision with ≥ two positive deep cultures (documented treatment failures) were compared to those who did not.

RESULTS

The 17 patients that had ≥ two positive cultures at their index revision were more likely to be male, to have had ream and run procedures, and to have higher loads of Cutibacterium on pre-operative cultures of their unprepared skin. The five patients that had documented treatment failure had higher loads of Cutibacterium on their skin and in deep cultures obtained at their index revision.

CONCLUSION

Patients harboring high loads of Cutibacterium on their unprepared skin prior to revision and high loads of Cutibacterium on deep cultures at the time of their index revision are at increased risk for failure of implant exchange and antibiotics to resolve a Cutibacterium PJI.

Clinical Outcome of Two-Stage Revision after Periprosthetic Shoulder Infection

Background: Periprosthetic shoulder infections are devastating complications after shoulder arthroplasty. A potential treatment concept is a two-stage prosthesis exchange. Data are sparse in terms of clinical outcome, including infection-free survival and patient satisfaction after this procedure. In the present study, we investigated recurrence of infection, revision-free survivorship and clinical outcome following two-stage revision due to periprosthetic shoulder infection. Furthermore, reasons for poor outcome were analyzed. Methods: Sixteen patients undergoing two-stage revision after shoulder joint infection were retrospectively identified. Recurrence of infection was analyzed by Kaplan–Meier survival curve. Clinical outcome was quantified with subjective shoulder value (SSV), “quick” Disabilities of the Arm, Shoulder and Hand (qDASH) and Rowe score. Range of motion (ROM) was measured pre- and postoperatively. Postoperative scores and ROM were compared in a subgroup analysis according to different reimplanted prosthesis types. Results: The reinfection-free implant survival was 81% after one year and at final follow-up (FU; mean of 33.2 months). The overall revision-free survival amounted to 56% after one year and at final FU. Patients who received reverse shoulder arthroplasty (RSA) as part of reimplantation had less disability and long-term complications. This group demonstrated better subjective stability and function compared to patients revised to megaprostheses or large-head hemiarthroplasties. Conclusions: Two-stage revision following periprosthetic joint infection of the shoulder allows appropriate infection control in the majority of patients. However, the overall complications and revision rates due to mechanical failure or reinfection are high. Reimplantation of RSA seem superior to alternative prosthesis models in terms of function and patient satisfaction. Therefore, bone-saving surgery and reconstruction of the glenoid may increase the likelihood of reimplantation of RSA and potentially improve outcome in the case of infection-related two-stage revision of the shoulder.