BackgroundMusculoskeletal ultrasound is an established diagnostic technique for the assessment of tendon injuries. The purpose of the present study was to determine whether ultrasound is effective for evaluating peroneal tendon injuries, with surgical findings used as the standard of reference.MethodsFifty-eight patients with a suspected peroneal tendon injury were prospectively evaluated with use of dynamic ultrasound. Twenty-five patients were found to have peroneal tendon tears and were managed operatively. Five patients with normal peroneal tendons on ultrasound examination also were managed operatively for other reasons and are included in the series as the peroneal tendons were inspected at the time of the procedure. Ultrasound and surgical criteria were used to grade the peroneal tendons on a scale from grade 0 (normal tendon) to grade III (tendon rupture).ResultsOf the sixty tendons that were evaluated operatively, twenty-five were found to be torn. The sensitivity, specificity, and accuracy of ultrasonography were 100%, 85%, and 90%, respectively.ConclusionsThe use of dynamic ultrasound is effective for determining the presence or absence of a peroneal tendon tear and should be considered a first-line diagnostic tool.Level of EvidenceDiagnostic Level III. See Instructions to Authors for a complete description of levels of evidence.