Ultrasound Features of Ankle Retinacula: Normal Appearance and Pathologic Findings

Abstract

Disorders of retinacula are frequent in acute and repetitive microtrauma of the ankle. Ultrasound (US), thanks to its spatial resolution and dynamic capabilities, is routinely used in the evaluation of the posttraumatic ankle for accurate delineation of ligaments and tendons. In addition, US can provide a depiction of normal retinacula and a detailed assessment of their pathologic changes. An accurate US assessment of ankle retinacula is helpful in choosing the proper treatment. In this pictorial essay, we briefly review the normal anatomy of ankle retinacula, describe their normal US appearance, and present a wide range of US pathologic abnormalities.

Advanced Ankle and Foot Sonoanatomy: Imaging Beyond the Basics

“…The SER is a transverse rectangular band proximal to the ankle joint. It attaches medially on the anterior crest of the tibia and medial malleolus and laterally on the lateral crest of the fibula and the lateral malleolus [38,39]. From medial to lateral, it covers the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and peroneus tertius tendons.…”

“…From medial to lateral, it covers the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and peroneus tertius tendons. A separate tunnel for the tibialis anterior tendon is formed by the superficial and deep fibers in 25% of cases [39].…”

“…The IER is a Y-shaped structure comprising the frondiform ligament and the oblique superomedial and inferomedial bands. The oblique superolateral band is present in various percentages of cases (25-81%) and, when present, shapes the IER into the cruciform configuration [39]. The frondiform ligament is the main part of the IER, retaining the extensor digitorum longus and peroneus tertius (PT) tendons against the talus and calcaneus.…”

“…The oblique inferomedial band arises from the apex of the frondiform ligament and is directed towards the naviculocuneiform joint. The oblique superolateral band, if present, is usually the thinnest and crosses over the AITFL to insert on the lateral malleolus [38,39].…”

“…It forms the roof of the tarsal tunnel. Within the tunnel, TP, flexor digitorum longus, and flexor hallucis tendons are compartmented by fibrous septa from the FR [39].…”