Plantar Tendons of the Foot: MR Imaging and US

Abstract

Tendon disorders along the plantar aspect of the foot may lead to significant symptoms but are often clinically misdiagnosed. Familiarity with the normal anatomy of the plantar tendons and its appearance at magnetic resonance (MR) imaging and ultrasonography (US) is essential for recognizing plantar tendon disorders. At MR imaging, the course of the plantar tendons is optimally visualized with dedicated imaging of the midfoot and forefoot. This imaging should include short-axis images obtained perpendicular to the long axis of the metatarsal shafts, which allows true cross-sectional evaluation of the plantar tendons. Normal plantar tendons appear as low-signal-intensity structures with all MR sequences. At US, accurate evaluation of the tendons requires that the ultrasound beam be perpendicular to the tendon. The normal tendon appears as a compact linear band of echogenic tissue that contains a fine, mixed hypoechoic and hyperechoic internal fibrillar pattern. Tendon injuries can be grouped into six major categories: tendinosis, peritendinosis, tenosynovitis, entrapment, rupture, and instability (subluxation or dislocation) and can be well assessed with both MR imaging and US. The radiologist plays an important role in the diagnosis of plantar tendon disorders, and recognizing their imaging appearances at MR imaging and US is essential.

Advanced Ankle and Foot Sonoanatomy: Imaging Beyond the Basics

“…After curving around the medial malleolus, the TP tendon divides into the anterior, middle, and posterior components just proximal to the navicular. It has multiple insertions on the hindfoot (except the talus), midfoot, and the base of the forefoot ( Figure 11A,B) [49]. The anterior component, also called the direct tendon, is the largest portion and inserts onto the navicular and medial cuneiform.…”

“…The middle component, also called the tarsometatarsal tendon, inserts onto the intermediate and lateral cuneiforms, cuboid, second to fourth metatarsal bases, PL, and flexor hallucis brevis tendons [50]. The posterior component arises from the main tendon proximal to the navicular and curves backward to insert on the anterior aspect of the sustentaculum tali [49].…”

“…To visualize the tarsometatarsal component of the tendon, the transducer is moved more inferiorly to follow it running under the abductor hallucis muscle. Evaluation of the distal tarsometatarsal insertions is difficult due to the deep location ( Figure 21C) [49]. Moving the transducer further to the plantar surface, flexor hallucis longus and flexor digitorum longus tendons will be visualized ( Figure 21D).…”

Os peroneum imaging: normal appearance and pathological findings

“…Once the PTub is detected, the transducer is moved forward along the PLT to the cuboid. When present, the OP is visualized at this level as a hyperechoic structure showing posterior shadowing [22]. Once detected, the OP must be analysed on both axial and coronal oblique planes.…”

“…The OP can be appreciated on axial, sagittal and coronal planes, especially if a 3D technique and small slice thickness are employed. Since the OP is located in a transition zone between the lateral and plantar course of the peroneus longus tendon, it is important to properly study this structure by orienting axial planes perpendicular to the long axis of the metatarsal shaft [22]. A correct orientation of planes helps minimize “magic angle” artefacts and also to correctly depict pathologies of the synovial sheaths.…”