Septic arthritis is a life-threatening emergency with considerable mortality.  As such, the prompt diagnosis and treatment of the affected joint is a major concern.  However, monoarticular arthritis is a nonspecific presentation and as in our patient, an unrelated event such as trauma, overuse, or vaccine administration can mask the affected joint.

Typically, septic arthritis demonstrates a bimodal distribution; young patients with greater vascularization of the joints and older patients with potential comorbidities and prostheses are more susceptible to initial inoculation of the joint capsule [1]. The placement of long-term tunneled hemodialysis catheters is an established practice, with well-described benefits and commensurate well-described risks [2].  Short-term catheters are useful in patients whose AV fistulae have yet to mature; while longer-term catheterization is indicated in patients for whom AV fistula formation is unsuccessful or contraindicated [3].  Infection is a known complication of long-term tunneled catheter placement.  While estimates as to the prevalence of infection in PermaCath placement vary, one descriptive analysis of 214 patients estimated infection rates of approximately 12%, another notable finding of this study was a higher mean age in patients who experienced infection (67.64 years) as opposed to the overall population of patients receiving long-term hemodialysis catheterization (57.67 years) [4].   One small (n=15) retrospective review demonstrated findings that were in many ways demographically consistent with our patient.  In their study of septic arthritis in patients on hemodialysis for ESRD, 12 of 15 patients demonstrated clear access-site related sources of the sepsis, and 13 of the 15 patients had Staphylococcal species isolated from cultures [5].

In 2011, a systematic review of 34 articles, Carpenter et al. highlighted that the specificity, sensitivity, and likelihood ratios for various risk factors derived from the patient’s history and physical presentation [6].  Of these factors, pain on motion, joint effusion, and limited range of motion were highly (>92%) sensitive; while these findings are nonspecific very few septic arthritis cases will present without these symptoms.  Redness, on the other hand, is a much less sensitive finding.  While the sensitivity varied between the individual publications reviewed, the range of 13 - 64% sensitivity made it one of the less prevalent symptoms, supporting the conclusion that targeted imaging is warranted when suspicion of septic arthritis is high [6].  Indeed, another case report of atypically presenting septic arthritis in an elderly female concludes with the advice “Clinicians must keep in mind that septic arthritis can present atypically, especially in elders; thus, septic arthritis must be included in the differential diagnosis of any patient presenting with joint pain and effusion until this diagnosis is ruled out by sterile joint aspiration.”[7]  This statement, reinforcing the importance of maintaining septic arthritis as a differential with only limited symptomatology, is consistent with our experience in achieving optimal care for our patient.

Ultimately, elderly patients often express immune responses that would be considered atypical in a healthier cohort [1].  Due to the presence of comorbidities in this population, the importance of prompt and accurate diagnosis is even greater; but these comorbidities often compromise the quality of life and cause a financial burden for the patient.  Our patient serves as a reminder to maintain vigilance for infectious complications in patients with tunneled long-term hemodialysis catheters when they present with mild to moderate localized symptoms but more with generalized systemic symptoms.