These authors conducted a systematic review of the outcomes of revision surgery for periprosthetic shoulder infection (PSI) of the shoulder. The review include 34 studies with 754 patients.
Cutibacterium acnes (C. acnes) was the most common microorganism found both in PSI (33%) and persistent infections (40%); Coagulase negative Staph was found in 20%.
These patients with PSI had elevated WBC in 11%, elevated ESR in 61% and elevated C-reactive protein in 70%. Reverse shoulder arthroplasty had a lower prevalence of infection (P <.001).
The apparent eradication rate was 96% with 1 stage, 93% with permanent spacers, 86% with 2 stages, 85% with resection arthroplasty, and 65% with irrigation and debridement. The organisms responsible for persistent infections (99) were C. acnes (40%), MSSA (14%), CNS (10%), and S. epidermidis (10%).
While two stage surgery was the most commonly used treatment, these authors found that one-stage revision yielded better postoperative flexion and abduction and had fewer postoperative complications than irrigation and debridement, resection arthroplasty, and 2-stage surgery. Specifically, the postoperative Simple Shoulder Test scores were 5.3±2.3 after irrigation and debridement, 2.9±2.6 after resection arthroplasty, 4.4±2.7 after placement of a spacer, 6.1±3.5 after a one stage revision and 5.5±1.2 after a two stage revision.
Comment: This is a review of of 34 different articles reporting various approaches to surgical revisions for infected shoulder arthroplasties. It is of note that many of these revisions were performed long after the initial arthroplasty, suggesting the subtle presentation of many of these infections - especially those with C. acnes. It is of note that these C. acnes infections were among those most difficult to resolve.
Relevant information on the single stage revision can be found in the summaries below:
Single-Stage Revision Is Effective for Failed Shoulder Arthroplasty with Positive Cultures for Propionibacterium
Fifty-five shoulders without obvious clinical evidence of infection had a single-stage revision arthroplasty. Specifically all components (humeral and glenoid) were removed, a thorough debridement was carried out and a new humeral hemiarthroplasty was inserted with Vancomycin impregnated allograft. The residual glenoid bone was smoothed, but not bone grafted. No glenoid components were replaced.
Preoperative antibiotics were withheld until culture specimens were taken; a minimum of 5 tissue or explant specimens were obtained from each shoulder. Specimens were cultured for 21 days on blood agar (trypticase soy agar with 5% sheep blood), chocolate agar, Brucella agar (with blood, hemin, and vitamin K), and brain-heart infusion broth. Bacteria that were isolated received a full species-level identification by means of 16S rDNA sequencing.
The culture-positive group were 89% male with a mean age of 63.5 ± 7.2 years. The mean Simple Shoulder Test (SST) scores for the 27 culture-positive shoulders improved from 3.2 ± 2.8 points before the surgical procedure to 7.8 ± 3.3 points at a mean follow-up of 45.8 ± 11.7 months after the surgical procedure (p < 0.001), a mean improvement of 49% of the maximum possible improvement.
These authors point out that cultures taken at the time of revision shoulder arthroplasty are often positive for Propionibacterium. They tested the hypothesis that the functional outcomes of revising Propionibacterium culture-positive failed arthroplasties with a single-stage revision and immediate antibiotic therapy are not inferior to the clinical outcomes of revising failed shoulder arthroplasties that are not culture-positive.
Fifty-five shoulders without obvious clinical evidence of infection had a single-stage revision arthroplasty. Specifically all components (humeral and glenoid) were removed, a thorough debridement was carried out and a new humeral hemiarthroplasty was inserted with Vancomycin impregnated allograft. The residual glenoid bone was smoothed, but not bone grafted. No glenoid components were replaced.
After all culture specimens were obtained, 15 mg/kg of vancomycin and 2 g of ceftriaxone were administered intravenously. Patients were continued on antibiotics until the results of the cultures were finalized. Two or more cultures became positive, the infectious disease service started intravenous ceftriaxone and/or vancomycin through a PICC line with oral rifampin for 6 weeks followed by oral antibiotics in the form of amoxicillin and clavulanate or doxycycline for a minimum of 6months.
The patient self-assessed functional outcomes for those shoulders with ≥2 positive cultures for Propionibacterium (the culture-positive group) were compared with shoulders with no positive cultures or only 1 positive culture (the control group).
Below is an example of what is referred to as a 'stealth' presentation in which there were no preoperative symptoms or signs of infection, yet the cultures from revision surgery were strongly positive.
The culture-positive group were 89% male with a mean age of 63.5 ± 7.2 years. The mean Simple Shoulder Test (SST) scores for the 27 culture-positive shoulders improved from 3.2 ± 2.8 points before the surgical procedure to 7.8 ± 3.3 points at a mean follow-up of 45.8 ± 11.7 months after the surgical procedure (p < 0.001), a mean improvement of 49% of the maximum possible improvement.
The control group were 39% male with a mean age of 67.1 ± 8.1 years. The mean SST scores for the 28 control shoulders improved from 2.6 ± 1.9 points preoperatively to 6.1 ± 3.4 points postoperatively at a mean follow-up of 49.6 ± 11.8 months (p < 0.001), a mean improvement of 37% of the maximum possible improvement.
Subsequent procedures for persistent pain or stiffness were required in 3 patients (11%) in the culture-positive group and in 3 patients (11%) in the control group; none of the revisions were culture-positive.
The authors concluded that the clinical outcomes after single-stage revision for Propionibacterium culture-positive shoulders were at least as good as the outcomes in revision procedures for control shoulders. Two-stage revision procedures may not be necessary in the management of these cases.
Fourteen patients reported side effects to antibiotics, indication that patients should be educated with regard to potential antibiotic side effects.
Another article, One-stage exchange of septic shoulder arthroplasty following a standardized treatment algorithm, reported a retrospective study of a smaller series of 14 shoulders (average age 71, half men (note the older age and greater % women than the prior study) having a single stage exchange of septic shoulder arthroplasties that had an isolated microorganism from synovial fluid aspiration or synovial biopsy with an antibiotic susceptibility profile prior to revision surgery. If no microorganism was isolated or the underlying pathogen was a difficult-to-treat microorganism (not accessible for biofilm active antibiotics, enterococci, and fungi), 2-stage exchange was performed.
For patients in whom septic shoulder arthroplasty was suspected, a diagnostic algorithm was followed to exclude or prove infection prior to revision surgery. The presumably infected shoulder was aspirated under aseptic conditions prior to revision surgery. Two weeks prior to aspiration, antibiotic treatment was suspended and all cultures were incubated for 14 days. In 12 patients, the underlying microorganism was identified in the synovial fluid obtained by aspiration. In 2 patients showing signs of infection with elevated serum C-reactive protein levels and synovial (WBC) counts, no microorganism grew in the synovial fluid. Consequently, they had to undergo an open biopsy, wherein infection was defined as a positive culture on at least 2 of the 5 resected tissue samples. If no microorganism was isolated prior to exchange surgery or the underlying pathogen was a difficult to-treat microorganism (not accessible for biofilm-active antibiotics, enterococci, and fungi, 2-stage exchange had to be performed.
The requirement for 1-stage exchange was an isolated microorganism from synovial fluid aspiration or synovial biopsy with an antibiotic susceptibility profile. Prior to surgery, we received a prescription from our microbiologist for local and systemic antibiotic therapy based on the antibiotic susceptibility profile of the isolated microorganism. The aim of the surgical procedure was to remove the infected prosthesis, followed by extensive débridement and insertion of a new prosthesis.
The mean follow-up period was 5.8 years. The most and second most commonly detected microorganisms were Cutibacterium acnes (formerly Propionibacterium acnes), and Staphylococcus epidermidis, respectively.
The requirement for 1-stage exchange was an isolated microorganism from synovial fluid aspiration or synovial biopsy with an antibiotic susceptibility profile. Prior to surgery, we received a prescription from our microbiologist for local and systemic antibiotic therapy based on the antibiotic susceptibility profile of the isolated microorganism. The aim of the surgical procedure was to remove the infected prosthesis, followed by extensive débridement and insertion of a new prosthesis.
The mean follow-up period was 5.8 years. The most and second most commonly detected microorganisms were Cutibacterium acnes (formerly Propionibacterium acnes), and Staphylococcus epidermidis, respectively.
At 1-stage exchange, patients received local and systemic antibiotics based on the susceptibility profile of the microorganism.
Twelve patients with insufficient rotator cuffs received reverse shoulder arthroplasty, whereas 2 patients with intact rotator cuffs underwent anatomic total shoulder arthroplasty. The infection-free survival rate at 1 and 5 years was 100% and 93% (95% confidence interval [CI], 59%-99%), respectively, with 1 recurrence of infection 22 months after 1-stage exchange. Another patient with limited range of motion underwent revision 6 months postoperatively, leading to a revision-free survival rate of 93% (95% CI, 59%-99%) and 86% (95% CI, 54%-96%) at 1 and 5 years, respectively. The mean preoperative Constant score was 27 and the mean followup Constant score was 65 (range, 44-95); this calculates to an improvement of 52% of the maximal possible improvement.
Comment: While a two-stage revision may be indicated for the 'obvious' infections, these articles suggests that a single stage revision may be sufficient for the management of 'stealth' presentations.
It is important to distinguish between (a) the 'obvious' presentation of a shoulder infection with findings such as abnormal blood tests (WBC, ESR, C-reactive protein), erythema, fever, and/or wound drainage from (b) the 'stealth' presentation in which none of these findings are present in shoulder arthroplasties revised for pain, stiffness or component loosening combined with cultures positive for organisms such as Propionibacterium. While in the past some have referred to the second group of cases as "unexpected positive cultures in revision shoulder arthroplasty", it is now preferable simply to report the clinical findings (i.e. is there obvious clinical evidence of infection?), the number of specimens, and the culture results. Furthermore, since it is not currently possible to distinguish "true infections", "contamination", "false-positive cultures", "non-pathogenic Propionibacterium growth", it is preferable to avoid these terms and, again, reporting the clinical findings, the number of specimens, and the culture results.
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Comment: While a two-stage revision may be indicated for the 'obvious' infections, these articles suggests that a single stage revision may be sufficient for the management of 'stealth' presentations.
It is important to distinguish between (a) the 'obvious' presentation of a shoulder infection with findings such as abnormal blood tests (WBC, ESR, C-reactive protein), erythema, fever, and/or wound drainage from (b) the 'stealth' presentation in which none of these findings are present in shoulder arthroplasties revised for pain, stiffness or component loosening combined with cultures positive for organisms such as Propionibacterium. While in the past some have referred to the second group of cases as "unexpected positive cultures in revision shoulder arthroplasty", it is now preferable simply to report the clinical findings (i.e. is there obvious clinical evidence of infection?), the number of specimens, and the culture results. Furthermore, since it is not currently possible to distinguish "true infections", "contamination", "false-positive cultures", "non-pathogenic Propionibacterium growth", it is preferable to avoid these terms and, again, reporting the clinical findings, the number of specimens, and the culture results.
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