What do positive and negative Cutibacterium culture results in periprosthetic shoulder infection mean? A multi-institutional control study

Revision of failed reverse total shoulder arthroplasty with reverse: short-term clinical outcomes

BACKGROUND

The prevalence of failed reverse total shoulder arthroplasty (rTSA) is increasing. This can often present a challenging clinical situation with substantial bone loss and limited reconstruction options. This study reports a single tertiary referral center's experience with revision of failed rTSA managed with revision rTSA of bone-interfacing components.

METHODS

After institutional review board approval, all revision shoulder arthroplasty cases performed at a single institution between 2012 and 2020 were reviewed. Cases in which rTSA was revised to a new rTSA construct with revision of at least 1 bone-interfacing implant (humeral stem and/or baseplate) with a minimum 2-year follow-up were identified. Characteristics of revision cases-including indications, bony stock, revised components, and use of bone graft-were collected. All patients were contacted for patient-reported outcome measures at a minimum of 2 years after surgery. In addition, the incidence and indication for any reoperation after revision were determined.

RESULTS

Thirty-three patients with an average age of 66 years (range: 46-82 years), with 19 (58%) being female, met the inclusion criteria and had a mean follow-up of 4.2 years (range: 2-8 years). The most common indication for revision rTSA included humeral component loosening (33%; 11/33), baseplate loosening (27%; 9/33), and instability (21%; 7/33). Prerevision infectious workup demonstrated no cases of periprosthetic shoulder infection. Thirteen cases had massive bone loss-5 treated with humeral allograft prosthetic composite, 5 with glenoid bone grafting, and 3 with custom glenoid implant. In total, 10 of 33 cases (30%) required reoperation at a mean of 13 months (range: 1-44 months) for instability (4), humeral loosening (2), infection (1), baseplate loosening (1), or periprosthetic fracture (1). The reoperation rate for patients with revised baseplates only, humerus only, or combined was 23% (3/13), 28% (5/18), and 27% (3/11), respectively. Overall, the visual analog scale pain score improved from 6.5 preoperatively to 2.0 (P < .001), and the American Shoulder and Elbow Surgeons score improved from 30.7 to 67.5 (P < .001). However, the postoperative Single Assessment Numeric Evaluation score averaged only 51.2% (range: 2-100%).

CONCLUSION

This study demonstrates that failed rTSA can be salvaged with a revision rTSA. However, patient expectations for functional improvements should be tempered, and a high reoperation rate should be expected.

Defeating the Hidden Foe: Antibiotic Therapy and Clinical Outcomes of Cutibacterium acnes Spinal Implant Infections

BACKGROUND

Cutibacterium acnes can cause spinal implant infections. However, little is known about the optimal medical management and outcomes of C. acnes spinal implant infections (CSII). Our study aims to describe the management of patients with CSII and evaluate the clinical outcomes.

METHODS

We performed a retrospective cohort study of patients aged 18 years or older who underwent spinal fusion surgery with instrumentation between January 1, 2011, and December 31, 2020, and whose intraoperative cultures were positive for C. acnes. The primary outcome was treatment failure based on subsequent recurrence, infection with another organism, or unplanned surgery secondary to infection.

RESULTS

There were 55 patients with a median follow-up (interquartile range) of 2 (1.2-2.0) years. Overall, there were 6 treatment failures over 85.8 total person-years, for an annual rate of 7.0% (95% CI, 2.6%-15.2%). Systemic antibiotic treatment was given to 74.5% (n = 41) of patients for a median duration of 352 days. In the subgroup treated with systemic antibiotics, there were 4 treatment failures (annual rate, 6.3%; 95% CI, 1.7%-16.2%), all of which occurred while on antibiotic therapy. Two failures occurred in the subgroup without antibiotic treatment (annual rate, 8.8%; 95% CI, 1.1%-31.8%).

CONCLUSIONS

Our study found that the estimated annual treatment failure rate was slightly higher among patients who did not receive antibiotics. Of the 6 failures observed, 4 had recurrence of C. acnes either on initial or subsequent treatment failures. More studies are warranted to determine the optimal duration of therapy for CSII.

[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.