LAUSR

History A 34-year-old man without underlying medical conditions came to the emergency department for evaluation of persistent pain over the volar portion of his right fifth finger after a fall during a football match 3 days before. At physical examination, the injured finger was swollen and purple. Passive and active flexion of the proximal and distal interphalangeal joints were compromised, without interphalangeal instability. Radiography was performed in the emergency department, and the patient was released with a diagnosis of a fifth digit sprain. After the senior radiologist (V.M.C.) reviewed the radiographs, the patient was called back for assessment with ultrasonography (US) on the same day. US was performed with an Aplio 500 unit (Toshiba Medical Systems, Tokyo, Japan) using a multifrequency linear array 7.2-18.0-MHz PLT-1204BX transducer focused at the level of the flexor tendon. The patient was sitting in front of the examiner, with the hand lying palm up on the examination bed. No abnormality was observed during color Doppler US.