A Microcurrent Dressing Reduces Cutibacterium Acnes Colonization in Patients Undergoing Shoulder Arthroplasty or Arthroscopy: A Prospective Case Series

Abstract

Background: Cutibacterium acnes infections in the shoulder remain a significant concern in the setting of shoulder arthroplasty. Purpose: We sought to evaluate the efficacy of a microcurrent dressing in reducing C. acnes skin colonization and thereby reducing the risk of periprosthetic joint infection of the shoulder. Methods: This study was designed as a prospective case series. From October 2017 to February 2019, patients undergoing elective shoulder arthroplasty or arthroscopic shoulder surgery at a major academic medical center were offered enrollment; they signed an informed consent to participate. Patients under the age of 18, scheduled for revision shoulder arthroplasty, or with sensitivity or allergy to silver, zinc, or latex were excluded. Subjects underwent skin culture swab of the shoulder in the mid-point of the planned deltopectoral incision. The JumpStart (Arthrex; Naples, FL) microcurrent dressing was then placed over the area of the planned incision, and a full-thickness skin biopsy was harvested from the incision at the initiation of the surgical procedure. All specimens were cultured for C. acnes by the hospital’s clinical microbiology laboratory with standard anaerobic technique. Results: Thirty-one subjects were enrolled in the study. Those who demonstrated no growth at baseline for the control specimen were excluded from further analysis (N = 11), given the absence of preoperative C. acnes colonization. Culture results from the 20 remaining subjects revealed significantly diminished C. acnes skin growth at the time of surgery compared to baseline. Sixty percent (12 of 20) of the subjects with positive skin swabs at baseline demonstrated no growth in the skin biopsy specimens at the time of surgery. There were no adverse events associated with the application of the microcurrent dressing. Conclusion: This prospective case series found that preoperative application of a microcurrent dressing resulted in significantly diminished C. acnes skin burden at the time of surgery in patients undergoing elective shoulder arthroplasty or arthroscopic shoulder surgery. Further study is warranted to investigate whether this preoperative intervention may contribute to a reduction in perioperative infections, including prosthetic joint infection.

Introduction

Deep periprosthetic infection of the shoulder following total joint arthroplasty (TJA) is a major complication. Although it occurs in only a small percentage of patients (~1%), it results in substantial morbidity and a decline in functional outcomes [3]. A 2-stage revision with exchange is commonly required to clear the infection and provide the best opportunity for prosthetic replantation [3,10 –12,16]. Following the removal of the infected components, a course of 4 to 6 weeks of parenteral antibiotics is commonly completed and resolution of the infection confirmed through erythrocyte sedimentation rate, C-reactive protein levels, and repeated aspiration or biopsy of the joint [12,15]. In most instances, a temporary spacer of antibiotic-loaded cement is inserted at the first stage and removed at the second operation if the infection is cleared.

C. acnes is a Gram-positive, non-spore-forming, anaerobic bacillus found in lipid-rich areas, including hair follicles, sebaceous glands, and moist areas of the shoulder and axilla [10]. Owing to its low virulence, infections caused by C. acnes typically have a low-grade, indolent course, with shoulder pain often the only presenting symptoms after prosthetic replacement. C. acnes is particularly challenging to diagnose and to eradicate. It is a substantial source of morbidity with shoulder arthroplasty [1,5,9,11,12].

Various strategies to limit shoulder prosthetic joint infection have been described, including preoperative skin washing and intraoperative delivery of various agents (vancomycin powder, soap, etc). Despite this, C. acnes infections of the shoulder remain a significant concern in shoulder arthroplasty.

Microcurrent skin dressings have been previously described as an adjunct to enhance skin wound healing. These dressings are believed to enhance healing by facilitating the stages of wound repair [13,17]. Microcurrent dressings have also been described to promote a bactericidal effect against skin pathogens [2,6]. The application of a microcurrent dressing in the preoperative setting, however, has not been studied. It is possible that reduction or elimination of C. acnes colonization preemptively may reduce the incidence of a periprosthetic joint infection. Given the morbidity and cost of such infections, this noninvasive and simple intervention could result in a significant reduction in the incidence of infection.

JumpStart (Arthrex; Naples, FL) is a wireless, advanced, microcurrent-generating dressing used for the management of surgical incision sites. This dressing has been proposed for application to all surgical incisions, especially in conditions in which skin or wound healing is a significant clinical concern. Microcell batteries made of silver and zinc generate an electrical current when activated by conductive fluids, such as saline, hydrogel, or wound exudate. These microcells create low-voltage electrical fields to stimulate the surrounding area and to provide antimicrobial protection to assist with wound healing. JumpStart has demonstrated superior broad-spectrum bactericidal activity as a wound dressing against antibiotic-resistant strains of wound isolates within 24 hours [6].

The use of JumpStart as a prophylactic preoperative dressing to alter the skin flora and thereby decrease the risk of periprosthetic joint infection has not been investigated to date. The objective of this study was to evaluate the efficacy of a microcurrent dressing in reducing C. acnes skin colonization and thereby reducing the risk of periprosthetic shoulder infection.

Methods

This prospective case series was approved by our medical center’s Institutional Review Board. From October 2017 to February 2019, patients undergoing elective shoulder arthroplasty or arthroscopic shoulder surgery at a major academic medical center were offered enrollment. Inclusion was limited to patients scheduled to undergo elective shoulder arthroplasty or arthroscopic shoulder surgery; they signed an informed consent to participate. Subjects under the age of 18, patients scheduled for revision shoulder arthroplasty, or those with sensitivity or allergy to silver, zinc, or latex were excluded from enrollment.

Two days prior to scheduled elective shoulder surgery, subjects underwent skin culture swab of the shoulder in the mid-point of the planned deltopectoral incision (control, Specimen 1). A single skin swab was passed back and forth over the skin five times in a 1 × 1 inch grid. Following this, the JumpStart microcurrent dressing was placed over the area of the planned incision (Fig. 1). The dressing was removed in the operating room immediately prior to prepping and draping the surgical field, and a repeat skin culture swab was collected from the same 1 × 1 inch grid used in the initial swab using the same technique (Specimen 2). At the initiation of the surgical procedure, a full-thickness skin biopsy was harvested from the incision and sent for culture, as C. acnes lives both on and within the dermal tissue (Specimen 3).

Fig. 1.

Photograph of JumpStart dressing applied to shoulder.

All specimens were cultured by the hospital’s clinical microbiology laboratory with standard anaerobic technique. Specimens were collected via eSwab and plated directly to both a sheep blood agar that was incubated aerobically (35°C, 6%CO²) and a Brucella blood agar plate that was incubated anaerobically. This provided the basis for colony counts. All plates were held for 15 days in accordance with our microbiology laboratory procedures for orthopedic sources.

Culture results were classified as follows: no growth, rare growth (1-5 colonies), few (6-15 colonies), moderate (16-99 colonies), and numerous (more than 100 colonies). For each subject, results were tabulated for each of the 3 cultures and analyzed with Fisher’s exact test. Statistical significance was defined as P < .05.

Results

Of 31 subjects enrolled in the study, 11 were excluded from further analysis because they demonstrated no growth at baseline for the control specimen, given the absence of preoperative C. acnes colonization. The microbiology results of 20 subjects were included for analysis (Fig. 2). Fisher’s exact test revealed significantly diminished C. acnes skin growth at the time of surgery compared to baseline (P = .004); 60% (12/20) of subjects with positive skin swabs at baseline demonstrated no growth in the skin biopsy specimens at the time of surgery (P = .001). There were no adverse events associated with the application of the microcurrent dressing.

Fig. 2.

Change in C. acnes growth over time.

Discussion

In this prospective case series, we found that preoperative application of a microcurrent dressing resulted in significantly diminished C. acnes skin burden at the time of surgery in patients undergoing elective shoulder arthroplasty or arthroscopic shoulder surgery. There were no complications associated with application of the dressing. These findings suggest that this safe and simple preoperative intervention may contribute to a reduction in perioperative infections, including prosthetic joint infection. In addition, it may be effective in reducing the incidence of surgical site C. acnes colonization, one of the most challenging organisms to identify and eradicate after periprosthetic joint infection. Other conventional interventions—including preoperative skin treatment, washing, and intraoperative antibiotics—have not been routinely effective in reducing C. acnes infection [8]. Benzoyl peroxide has been reported to be effective in reducing C. acnes skin colonization, but there is no evidence that it reduces subdermal or deep tissue burden of the bacteria [4,13].

Limitations of this study include the attrition of the study group due to the absence of baseline C. acnes colonization. In addition, we did not have baseline skin biopsy data, so it is difficult to interpret the skin biopsy data collected at the time of surgery. Furthermore, the primary outcome was a reduction or elimination of C. acnes growth, but it is not established that this reduction or elimination will directly correlate with a reduction in the incidence of periprosthetic infection. It appears from our data that the greatest reduction in C. acnes burden was realized in the reduction of subjects who demonstrated moderate growth at baseline, although it is unclear what the clinical relevance of this finding might be. Future studies are necessary via randomized controlled trials in a large series to assess any differences in confirmed prosthetic infection to definitively establish preventative efficacy and the number needed to treat.

While the rate of prosthetic joint infection after primary shoulder arthroplasty is approximately 1% to 4% in the literature, it can increase to as high as 10% in young, male patients after reverse arthroplasty [9]. A 2018 study by Sousa of lower extremity arthroplasty patients in Portugal estimated the economic impact of aseptic revision to be 6000 to 8000€, and 11 000 to 14 000€ for a 2-stage revision [14]. These numbers likely reflect substantially lower estimated costs in Portugal’s National Health Service compared to the United States and do not incorporate the additional impact of patients’ loss of financial productivity and disability. Similarly, Kurtz et al [7] reported that the annual cost of infected revisions to US hospitals increased from $320 million to $566 million during the study period and was projected to exceed $1.62 billion by 2020. Accordingly, any interventions that can mitigate the risk of prosthetic infection noninvasively and safely should be carefully considered for use in clinical practice. Our results reflect shoulder arthroplasty and C. acnes infection, but future studies can investigate the role of microcurrent dressing for other organisms and for all orthopedic procedures in which deep implant infection is a significant risk, including lower extremity arthroplasty, trauma, and spinal fusion procedures.

In conclusion, this prospective case series of patients undergoing elective shoulder arthroplasty or arthroscopic shoulder surgery found an association between preoperative application of a microcurrent dressing and significantly diminished C. acnes skin burden at the time of surgery, both at the skin surface and in the deep dermal tissues. There were no complications associated with application of the dressing. Further study into whether it is a safe and effective preoperative intervention to reduce periprosthetic joint infections is indicated.