Painful ankle

There's a complete "C" sign on the radiograph, associated with osteophyte arising from the sustentaculum tali. The T2weighted fat sat sagittal MRI was cunningly inserted to demonstrate subchondral cysts, and soft tissue oedema (albeit on a non-typical view). The coronal PD shows a very nice fibrous and bony talocalcaneal coalition.

Tarsal coalition (of which talocalcaneal is a subset) is thought to affect up to 1% of the population- but I feel it's more common than that. It is an abnormal bony/cartilaginous/fibrous union of the mid/hindfoot bones. These coalitions can occur in isolation, or in association with congenital problems (e.g. pes planus).

The common areas are: anterior calcaneus ("anteater sign") and navicular bone, and talocalcaneal. The endpoint is restriction of subtalar motion, resulting in flatfoot, deformity, pain, tarsal tunnel syndrome (by tension neuropathies) and peroneal tendon spasm.

Here's a very nice article by Julia Crim in 2004.

Imaging guided injection of (local anaesthetic) lignocaine and anti-inflammatory agents can be helpful in sealing the diagnosis.

Patient with pain at lateral hindfoot- and clinically, approximated anterolateral syndrome. The question: where is the pathology?

Pathology is in the subtalar joint. There is increased signal within the sinus tarsi, with thickening of the interosseous talocalcaneal ligament. Replacement of normal sinus tarsi fat. This is Sinus Tarsi Syndrome.

The sinus tarsi is an anatomical space bounded by the talus and calcaneum, the talocalcaneonavicular joint anteriorly and posterior facet of the subtalar joint posteriorly. It is medially continuous with the much narrower tarsal canal. The sinus tarsi contains the cervical ligament and the three roots of the inferior extensor retinaculum. The tarsal canal contains the interosseous talocalcaneal ligament and the deep and intermediate roots of the inferior extensor retinaculum. Both the sinus and the canal contain blood vessels - which are important for the nutrition of the talus - and nerves. The extensor digitorum brevis and bifurcate ligament lie anterior to the sinus tarsi.

Pain is relieved by injection of local anaesthetic into the subtalar joint.

Commonest underlying abnormalities:

interosseous talocalcaneal ligament tears;
subtalar instability osteochondral injuries of the subtalar joint;
arthrofibrosis of the subtalar joint;
degenerative disease of the subtalar joint;
fibrous tarsal coalition; and
chronic inflammatory changes in the sinus tarsi connective tissues


Plain radiographs and stress views are usually not helpful.

Pain can be relieved with injection of local anaesthetic and anti-inflammatory medications, or arthroscopic debridement if this fails.

...and patient jumps!! Then, the patient is referred for a scan for a lump in the posteromedial ankle.

Ultrasound scans reveal a hypoechoic spindle shaped nodule in continuity with hypoechoic linear structures, which are nerves. It is located (see second picture) within the neurovascular bundle between flexor hallucis longus and flexor digitorum longus tendons- consistent with a neuroma of a branch of the posterior tibial nerve.

Do not inject/aspirate nodules without prior imaging!

Here's an injury we don't see everyday. Young female with forced dorsiflexion of the foot.

It's a nutcracker injury of the calcaneocuboidal joint resulting in fractures of the tip of the anterior process calcaneus, and the superoposterior corner of the cuboid. In addition, subluxation of the calcaneocuboidal joint is present, with widening of the superior aspect of the joint.

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