An Uncommon Presentation of Polyarticular Septic Arthritis Following an Atraumatic Treadmill Run: A Case Report

Septic arthritis is an urgent orthopedic condition typically caused by gram-positive bacteria, such as Staphylococcus aureus. It poses a risk for complications like osteomyelitis, osteonecrosis, sepsis, and chronic pain. In this case report, we present a 33-year-old woman with a history of atopic dermatitis, obesity (body mass index 40 kg/m²), and hypertension, who presented to the emergency room with fever and right ankle pain following a jog on the treadmill. Initially, she was diagnosed with plantar fasciitis, for which she was prescribed corticosteroids. Her condition rapidly progressed, and she was ultimately diagnosed with polyarticular septic arthritis and admitted for treatment. Her condition was further complicated by deep vein thrombosis, avascular necrosis, and osteomyelitis of the right lower extremity. Despite initial treatment with antibiotics and surgical intervention, her symptoms persisted, leading to repeat surgery, readmission, and chronic mobility problems.  In this article, we present a case of atraumatic onset of septic arthritis after exercise in a young patient without classic immunosuppression. This case underscores the importance of considering a diagnosis of septic arthritis in patients with overlapping risk factors such as atopic dermatitis, obesity, and corticosteroid use. It illustrates the benefits of advanced imaging for accurate, prompt assessment and intervention. The condition's early presentation can mimic other inflammatory disorders, complicating diagnosis. This case report contributes to the growing but limited body of literature that associates septic arthritis with risk factors such as atopic dermatitis, obesity, and corticosteroid use.