Anatomy, pathology and guideline for scanning the spring ligament in the foot

The spring ligament (SL) complex is composed of the superomedial, medioplantar, and inferoplantar calcaneonavicular (CN) ligaments. The SL is one of the major stabilizers of the longitudinal arch and for supporting the head of the talus. With the foot rotated externally with dorsalflexion, the transducer is initially placed in the transverse plane inferior to the medial malleolus and over the sustentaculum tali. The transducer is then moved anteriorly and angled superiorly toward the talar head, allowing the superomedial CN ligament to be identified in long axis. The medioplantar and inferoplantar CN ligaments are not consistently visualized on US because of their deep and complex course. The superomedial CN ligament is the most likely to be injured. Disorders of the CN ligament are associated with tibialis posterior tendon tears, both of which contribute to flatfoot deformity. Injury to the SL appears as thickening, thinning, or frank discontinuity. US is an effective tool for assessing SL abnormalities in patients with symptomatic posterior tibialis tendon dysfunction > Alves et al (2018)