[Ultrasonic assessment of the capsular-ligamentous structures of the ankle. Normal features]

The study of normal ankles by means of US has enabled the authors to define the articular system so as to obtain a useful reference for the study of pathological ankles. A real-time (Ansaldo AU 530) unit with a 10 MHz sectorial probe was employed together with a Toshiba unit with a 7.5 MHz sectorial probe. In 6 cases, the stretching of the capsuloligamentous system before arthroscopy was examined. The authors' attention focused on 3 major functional anatomic areas: the talofibular ligament area, the calcaneofibular ligament area, and the deltoid ligament area. The comparison of US scans before and after stretching the capsula with a physiological solution allowed the most interesting structures to be recognized and quantified from a US-anatomical point of view. Useful parameters were both the length of the lateral aspect of the ligament (mean difference in length between rest and exercise conditions: 15 mm for the anterior talofibular ligament and 14 mm for calcaneofibular ligament) and the thickness of intra-articular echoes (mean value: 5 mm).