Ankle Joint

Question 1

Articulating surfaces

Answer 1

Mortise - bracket shaped socket formed by tibia and fibular

Talus body fits into mortise

Question 2

Ligaments

Answer 2

• Medial ligament - attached to the medial malleolus, consists of 4 separate ligaments attaching to the talus, calcaneus and navicular bones, resists over-eversion of the foot
• Lateral ligaments - 3 separate ligaments..
  1) Anterior talofibular - lateral malleolus -> lateral talus
  2) Posterior talofibular - lateral malleolus -> posterior talus
  3) Calcaneofibular - lateral malleolus -> calcaneus

Question 3

The ankle ring

Answer 3

Can be visualised as a ring in the coronal plane
Upper part - articular surfaces of tibia and fibula
Lower part - subtalar joint (talus and calcaneus)
Sides - medial and lateral ligaments
Rings often break in 2 places -> when a fracture occurs there is often ligament damage too (wouldn’t show up on an X-ray)

Question 4

Movement

Answer 4

Plantarflexion - gastrocnemius, soleus, plantaris, posterior tibialis
Dorsiflexion - tibialis anterior, extensor hallucis longus, extensor digitorum longus

Question 5

Neurovasculature

Answer 5

Arterial supply - malleolar branches of anterior tibial, posterior tibial and fibular arteries
Innervation - tibial + deep fibular nerves

Question 6

Ankle sprain

Answer 6

Partial/complete tears in ligaments of ankle joint
Usually in plantarflexed weigh-bearing foot excessively inverted
Lateral ligament most likely damaged as it’s weaker and resists inversion
Anterior talofibular ligament most at risk of irreversible damage

Question 7

Pott’s fracture-dislocation

Answer 7

Bimalleolar (medial + lateral malleoli) or trimalleolar (medial, lateral malleoli + distal tibia) fracture
Forced eversion of the foot
1. Forced eversion pulls medial ligaments -> avulsion fracture of medial malleolus
2. Talus moves laterally, breaking off the lateral malleolus
3. Tibia forced anteriorly, shearing distal and posterior part against talus