MRI of the ankle (an approach)

MRI of the ankle is one of the more frequent examinations faced in daily radiological practice. This approach is an example of how to create a radiological report of an MRI of the ankle with coverage of the most common anatomical sites of possible pathology, within the ankle without claim for completeness.

Systematic review

A systematic review of the MRI of the ankle is essential since ankle anatomy itself is rather complex, pathologies and injury patterns are manifold and only rarely lead to an abnormality of a single structure but rather show diverse findings which might need to be addressed in further patient management.

Bones

The bony structures of the ankle, the distal tibia, distal fibula, talus, calcaneus, navicular and cuboid bone as well as the three cuneiforms and the bases of the metatarsal bones and their alignment are assessed:

• osseous tumors, ankle fractures/stress fractures, bone marrow changes

Distal tibiofibular joint

Assessment of the distal tibiofibular syndesmosis:

• syndesmosis injury

Tibiotalar joint

Assessment of the following structures:

• cartilage and subchondral bony structures of the tibial plafond
  • chondral and osteochondral injury, subchondral fractures and subchondral cysts, osteoarthritic changes, septic arthritis, Charcot joint
• lateral: anterior talofibular ligament (ATFL), calcaneofibular ligament (CFL), posterior talofibular ligament (PTFL) ligaments
  • ankle sprain, anterior talofibular ligament injury 
• medial: deltoid ligament
  • deltoid ligament injury, spring ligament injury
• joint space and capsule
  • effusion, joint effusion if present and possible intra-articular fragments or loose bodies
• synovitis, ankle impingement syndromes

Subtalar joint and sinus tarsi

• subchondral bony structures
• inferior extensor retinaculum
• cervical ligament (lateral), talocalcaneal interosseous ligament (medial)
  • sinus tarsi syndrome
  • extra-articular lateral hindfoot impingement syndrome 

Midtarsal joint

• dorsal talonavicular ligament
• spring ligament complex
• bifurcate ligament
• dorsal calcaneocuboid ligament
• the short and long plantar ligaments
  • midtarsal sprain

Posteromedial compartment / tarsal tunnel

Assessment of the following structures:

• tibialis posterior
  • tibialis posterior dysfunction
• flexor digitorum longus
• posterior tibial artery and veins / tibial nerve
• flexor hallucis longus tendon
  • tenosynovitis, tendinosis, tear
• variant anatomy: accessory flexor digitorum longus, accessory soleus, peroneocalcaneus internus, tibiocalcaneus internus muscles 
• tarsal tunnel syndrome

Peroneal compartment

Assessment of the following structures:

• peroneus longus
• peroneus brevis
  • tenosynovitis, tendinosis, tear
• superior and inferior peroneal retinaculum
  • ​superior peroneal retinaculum injuries
• variant anatomy: peroneus quartus muscles

Anterior compartment

• tibialis anterior
• extensor hallucis longus
• dorsalis pedis artery / deep peroneal nerve
• extensor digitorum longus tendon
  • tenosynovitis, tendinosis, tears
• variant anatomy: peroneus tertius, anterior fibulocalcaneus muscle, tibioastragalus anticus of Gruber muscle

Achilles tendon and calcaneus

• Achilles tendinosis, Achilles tendon tear
• paratenonitis
• Haglund deformity, enthesitis, preachillar bursitis
• calcaneal tuberosity avulsion fracture

Plantar fascia,  plantar soft tissues and muscles

• plantar fascia
  • plantar fasciitis, plantar fibromatosis, plantar fascial tear, plantar xanthoma, heel fat pad syndrome
• flexor digitorum brevis muscle, quadratus plantae muscle
  • muscle edema, fatty degeneration, Baxter neuropathy
• soft tissues
  • plantar vein thrombosis, lipoma

Common pathology

• ankle sprain, anterior talofibular ligament injury
• deltoid ligament injury
• syndesmosis injury
• osteochondral injury
• ankle impingement syndromes
• peroneus brevis tear
• tibialis posterior dysfunction
• Achilles tendon rupture
• plantar fasciitis