Isolated shoulder sepsis, in an otherwise healthy patient, is uncommon. This study examined the organisms involved, the type of surgery and antibiotic treatment, the outcomes and complications. The number of patients in this study is relatively small despite it being one of the largest in comparison to that published in the literature. The short followup of a minimum of 1 month (mean 6 months) precludes identifying possible late recurrences or the long-term sequelae of shoulder sepsis.
Prompt attention is needed to address joint infections before further cartilaginous and soft tissue damage occurs [4
]. When surgery is indicated, open and arthroscopic techniques appear equally accepted [8
]. Within the limits of followup we successfully treated 14 of 18 patients with only one surgery. Repeat surgery was needed in five patients as determined by the patient’s response (clinically the patients should have improvement in pain with passive and active range of motion, normalization of body temperature, and improvement in WBC, CRP, ESR values) to the initial operative treatment as well as the broad-spectrum intravenous antibiotics. In the two patients with negative cultures (both had been on oral antibiotics for over 3 days), these patients had isolated shoulder sepsis with frank purulence at the first procedure and all were treated with broad-spectrum antibiotics for 4 weeks with resolution of the infection.
The bacterial organisms in patients with native shoulder sepsis appear considerably different from those seen in patients with infected rotator cuff repair or shoulder arthroplasty [16
]. P. acnes is the most common organism present in the setting of infection after shoulder surgery [16
]. However, in our series of primary infections, only one of 19 shoulders had P. acnes. There has also been debate whether P. acnes represents a true organism or a contaminant. The low incidence of P. acnes in this study suggests P. acnes is likely not a contaminant from the laboratory results, and represents a true pathogen that is introduced into the shoulder at the time of shoulder surgery.
Cleeman et al. [4
] reported comorbidities in 87% of their patients (Table ). However, Lossos et al. [11
] reported 56% of their patients had an at-risk comorbidity. This is more in line with our findings of 47% (nine of 19). In the literature review performed by Lossos et al. [11
], 13% of patients with shoulder sepsis had another source of infection. Cleeman et al. [4
] had a 52% rate and Gelberman et al. [7
] also reported a 50% rate. Given that our study is on isolated shoulder sepsis, our rate was zero. The review of Lossos et al. [11
] suggests positive culture rates of 88%. This compares favorably with our rate of 89% (17 of 19). If Gram stains and cultures are negative, then synovial biopsy is recommended [4
A comparison of published demographics from previous studies
The most common organism reported in the literature as the cause of infection in shoulder sepsis is S. aureus (41% of cases) [4
]. In our series six of 19 (32%) were positive for S. aureus (one was MRSA), which is slightly less than previously published findings (Table ). Long-term sequelae following septic arthritis of the shoulder include arthropathy, rotator cuff tear, and osteomyelitis. Wick et al. [24
] reported on 15 patients who underwent arthrodesis of the shoulder after sepsis, 33% of whom had complications including nonunion and persistent draining sinus. Mileti et al. [14
] reviewed 12 postinfectious arthritic shoulders treated by shoulder arthroplasty. No patients in their series had reinfection. One patient underwent resection arthroplasty for recurrent MRSA after numerous attempts with more limited surgery.
A comparison of organisms cultured in previous studies
Treatment of isolated shoulder sepsis can be challenging. Gram-positive organisms are the most common cause of infection and initial antibiotic coverage should consider this. The patient should be thoroughly examined for any other potential sources of infection as well as any other systemic problems. Cartilage loss and/or irreparable rotator cuff pathology are potential sequelae from shoulder sepsis. Patients may require a resection arthroplasty and, even when aggressively treated, death is an unfortunate but possible outcome.
We found open or arthroscopic débridement in conjunction with appropriate antibiotics appears effective in eradicating infection in most adults who present with shoulder sepsis. Gram positive organisms caused the majority of isolated shoulder sepsis infections in this study. Over half the patients in our series had no known risk for developing joint sepsis per se. Functional outcome was poor in patients with irreparable rotator cuff tears and/or cartilage loss.