March 01, 2015
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Infection of reverse total shoulder arthroplasty requires active management

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Editor’s note: In this article from the FORTE organization, Filippo Familiari, MD, and FORTE president Gazi Huri, MD, discuss the features of a reverse total shoulder arthroplasty periprosthetic infection. Look for more articles from FORTE members in future issues of Orthopaedics Today Europe.

According to the Agency for Healthcare Research and Quality Database, the number of shoulder arthroplas­ties performed in the United States is becoming increasingly prevalent. More than 53,000 patients underwent shoulder arthroplasty in 2011, with an estimated increase to 75,000 per year by 2020. A potentially devastating complication following shoulder arthroplasty is periprosthetic infection. In­fection is associated with poor outcomes, technically difficult revision surgery, and increased cost.

Filippo Familiari

The prevalence of infec­tion following primary shoulder arthro­plasty has been reported to be between 0.7% and 4%, and even higher following revision surgery. Two large ret­rospective reviews noted infection rates of 0.7% and 1.2%. Bohsali and colleagues reported infections accounted for 4.6% of all complications following total shoulder arthroplasty (TSA). Singh and colleagues observed 5-year, 10-year and 20-year infection-free rates of 99.3%, 98.5% and 97.2%, respectively.

Reverse total shoulder arthroplasty (RTSA) was introduced in the late 1980s in France. RTSA provided orthopaedic surgeons with an alternative to TSA for patients with cuff tear arthropathy who has pain and loss of motion. Subsequently, the indications for the reverse prosthesis have expanded to include various pathologic processes that have previously been difficult to treat successfully and predictably. Although promising results have been documented for various shoulder conditions, complications after RTSA are reported to be as high as 75%, including instability, periprosthetic infection, hematoma, fracture, and neurologic injury. Infection rate after RTSA has been reported as high as 5%.

Risk factors for periprosthetic infection

Patient demographic and clinical characteristics such as diabetes, smoking, morbid obesity and rheumatoid arthritis (RA), have been associated with infection in orthopaedic surgeries.

Rheumatoid arthritis, obesity and revision of prior failed arthroplasty have been singled out as risk factors for periprosthetic infection after shoulder arthroplasty in several small series. Padegimas and colleagues identified primary shoulder arthroplasties performed in the United States from 2002 to 2011 from the National Inpatient Sample database. The authors demonstrated that comorbidities associated with periprosthetic infection were weight loss/nutritional deficiency (P = 0.00047), drug abuse (P = 0.0011), and anemia from blood loss (P = 0.00031) or iron deficiency (P < 0.0001). Moreover, demographic factors associated with periprosthetic infection were younger age (P < 0.0001) and male gender (P < 0.0001). The authors concluded risk factor modification may decrease RTSA infection incidence and help contain costs. Accordingly, Morris and colleagues assessed the association between patient demographic and clinical characteristics (age, sex, smoking, diabetes, RA, BMI and history of prior failed hemiarthroplasty or TSA) and periprosthetic infection after RTSA. The authors identified 15 periprosthetic infections (5.0%) among 301 primary RTSAs. They noted that patients with a history of RTSA for failed arthroplasty (P = 0.001) and patients <65 years of age (P = 0.021) had an increased risk for development of an infection. History of smoking, diabetes, RA or obesity was not found to contribute to an increased risk of infection after RTSA. Propionibacterium acnes (P. acnes) and Staphylococcus epidermidis have been shown as the most common offending pathogen in RTSA infections, ranging from 19% to 70%.

Management of infected arthroplasty

The infected shoulder prosthesis is a devastating complication. As experience of shoulder arthroplasty infection is not as wide as with infected knee or hip implants, there is still a lack of consensus about the optimal therapeutic strategy.

Antibiotic infusion should be started only after cultures are taken to allow speciation of the bacteria and antibiotics should tailored accordingly. Acute infection should be treated with thorough irrigation, debridement and polyethylene exchange. If a chronic infection does occur, a two-stage complete revision should be performed. In order to limit the amount of anesthesia and the morbidity of a second procedure to the patient, Beekman and colleagues reported successful one-stage revision. Zavala and colleagues reported successful treatment of infected RTSA with a combination of debridement, liner/glenosphere exchange, and intravenous antibiotics regardless of chronicity of the infection. Traditional staged resection arthroplasty can lead to significant bone and soft tissue loss and should be reserved for persistent infections or significant bone stock loss unsuitable for reimplantation. As suggested by Zhang and colleagues, utilization of an open biopsy prior to the reimplantation stage may be beneficial. The authors reported that 4 patients of 18 patients (22%) with periprosthetic infection had positive cultures during the open biopsy procedure even after a formal irrigation and debridement, implant resection, antibiotic spacer implantation, and a course of antibiotics. Interestingly, three patients out of four patients still had P. acnes infection. They were treated with another irrigation and debridement, antibiotic spacer implantation, and 6 weeks of culture-specific antibiotics. Using this protocol, the authors reported 100% eradication of infection in all patients.

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Disclosures: Familiari and Huri report no relevant financial disclosures.