The talocrural (ankle) joint is the junction of three bones: distal ends of tibia and fibular and the talus trochlear

The tibia and fibular are bound by the ligamentous structures that include the syndesmosis, anterior/posterior/transverse tibiofibular ligaments.

Collateral ligaments include the anterior and posterior fibulotalar ligaments, fibulocalcanear on the lateral side while the medial side is supported by the deltoid ligament and calcaneonavicular ligaments.

The ankle joint is not a pure hinge joint as there is some rotation around the helical axis of the joint due to the asymmetrical shape of the talus.

Medial aspect of left foot

Lateral aspect of left foot

Dorsal aspect left foot

Plantar aspect left foot

Normal anatomy of foot anterolateral muscles

Accessory soleus

• 2-5%

Accessory FDL

• 6-8%

Peroneus Quadratus

• 10-25%

Peroneocalcaneus internus

• 1%

Ultrasound image demonstrating accessory Soleus muscle

• 6-8%
• Symptomatic when passes through tarsal tunnel
• Origin:
  • FHL/ flexor retinaculum
• Insertion:
  • Blends with quadratus plantae

AFDL: accessory FDL muscle

• Noted between FHL and peroneals
• Origin: Fibula
• Insert: Calcaneus
• Usually asymptomatic, but may be issue with arthroscopy and n/v injury.

Axial MRI image

Yellow: Peroneocalcaneus Internus site

• Tendinosis
  • Insertional
  • Non-insertional
  • +/- tear
• Paratendinosis
• Bursa
  • Superficial
  • Retrocalcaneal
• Bone marrow

Lateral view of left foot with Achilles tendon insertion on calcaneus bone

Posterior aspect of calf area: Gastrognemius muscle

• XR
• US
  • High-resolution
  • Operator-dependent
• MRI
  • PD/PDFS
  • Sagittal and axial

Haglund deformity:

• Pressure from shoes
• Distal insertional fibres affected

Ultrasound longitudinal image showing Achilles tendinopathy at insertional area of calcaneus.

Sagittal MRI scan with thickening of Achilles at calcaneus insertion

• Older patient
• Overuse
• Degenerative
• Medication
• Upper 1/3

Longitudinal ultrasound image of Achilles tendinopathy with colour doppler demonstrating neovascularization.

Axial Achilles tendinopathy with ultrasound image demonstrating neovascularization.

Sagittal MRI scan

Axial MRI image. Achilles tendinopathy

Axial MRI fat suppression image. Increased signal in Achilles tendon

X-ray lateral ankle image demonstrating calcification in the Achilles tendon

• Paratendinitis = paratenonitis
• No tendon sheath
• Paratenon
• Posterior/medial/lateral
• Thickened with adhesions
• Crepitus

Sagittal MRI fat suppression scan image

Sagittal MRI image of the Achilles tendon, paratendinitis

Axial MRI image of Achilles tendon

Axial ultrasound image of the Achilles tendon

Axial ultrasound image of the Achilles tendon with Achilles paratendinitis

Longitudinal ultrasound image of the Achilles tendon with retrocalcaneus bursa swelling

Sagittal MRI fat suppression view of Achilles tendon demonstrating retrocalcaneal bursitis

• Partial thickness
  • Younger
• Full-thickness
  • Underlying tendinopathy
• status of plantaris tendon
• ? is there tissue interposition
  • Static/dynamic

Sagittal MRI image with partial Achilles tendon tear

Longitudinal ultrasound image of Achilles tendon with complete tendon tear

Sagittal MRI image with Os trigonum

Sagittal fat suppression MRI image with Os trigonum and associated inflammtion

X-ray ankle demonstrating posterior ankle Os trigonum

X-ray ankle in plantar flexion demonstrating posterior ankle impingement

• Overuse
• Associations with inflammatory arthropathies e.g. psoriasis

NOT associated with bony spur !

Differential diagnosis: fibromatosis/ tear

• Lateral collateral complex
• Syndesmosis
• Spring
• Deltoid
• Calcaneocuboid

MRI: axial and coronal images

Lateral complex

• Anterior talofibular
• Calcaneofibular
• Post. talofibular

X-ray of right ankle demonstrating torn syndesmosis with tibia and fibular diastasis

Axial MRI image demonstrating torn syndesmosis ligament complex

X-ray lateral ankle demonstrating posterior malleolar fracture

Axial MRI scan:

Posterior malleolar fracture (red arrows)