Introduction: Septic malleolar bursitis is a rare cause of ankle pain and swelling. It has been described in certain occupational and recreational activities that involve tight-fitting boots, such as figure skating. Court-ordered electronic monitoring devices are often worn on the ankle. It is not known whether these devices are a risk factor for the development of malleolar bursitis.

Case report: We describe a 41-year-old male under house arrest with an electronic monitoring device on his right ankle who presented to our emergency department with several days of progressive pain and swelling over the medial malleolus. Point-of-care ultrasound revealed a thick-walled cystic structure consistent with medial malleolar bursitis. Bursal aspiration was performed. Fluid culture yielded Staphylococcus aureus.

Discussion: Emergency physicians regularly see patients with ankle pain and swelling and must consider a comprehensive differential diagnosis. Septic malleolar bursitis is an uncommon but important cause of ankle pain and swelling that requires prompt diagnosis and intervention. Point-of-care ultrasonography may aid in the diagnosis. Additionally, emergency physicians should be aware of potential complications related to electronic monitoring devices.