Sprain of the first MCP joint is frequent. In patients with UCL tear, the adductor aponeurosis may become interposed between the distal site of ligament attachment and the ruptured ligament: this lesion, described by Stener, prevents ligamentous healing and requires surgical intervention. We present the results from a prospective study of 56 patients with first MCP sprain in order to determine the value of US by correlating with surgical findings. We propose a new dynamic maneuver during flexion-extension of the IP joint. This enables visualization of the adductor aponeurosis and its relationship to the UCL on US allowing detection of a Stener lesion when it exists. All patients with Stener lesion on US underwent surgery (32 operated patients): the sensitivity of US was 95.4% with a specificity of 80% for detection of Stener lesions. US, with the use of this specific dynamic maneuver is a reliable and reproducible tool for detecting Stener lesions. Review of video recordings allows visual comprehension of the examination for other health care providers.