S5) The Ankle Flashcards
What is the ankle joint?
The ankle joint (talocrural joint) is a hinge-type synovial joint located in the lower limb, formed by the bones of the leg and the foot – the tibia, fibula and talus
What is the mortise?
- The mortise is the hyaline cartilage-covered socket formed by the binding of the tibia and fibula together by strong tibiofibular ligaments
- The body of the talus fits snugly into the mortise
Describe the location and function of the medial ligament (deltoid ligament) of the malleolus
- Location: attached to the medial malleolus and consists of 4 ligaments which fan out and attach to the talus, calcaneus and navicular bones
- Function: resist over-eversion of the foot
Identify the different ligaments composing the medial ligament of the malleolus
Describe the location and function of the lateral ligament of the malleolus
- Location: attached the lateral malleolus and consists of three ligaments which fan out and attach to the talus and calcaneus bones
- Function: resists over-inversion of the foot
Identify the different ligaments composing the lateral ligament of the malleolus
Identify the possible movements of the ankle joint and the muscles involved
- Plantarflexion – gastrocnemius, soleus, plantaris and posterior tibialis (posterior compartment of leg)
- Dorsiflexion – tibialis anterior, extensor hallucis longus and extensor digitorum longus (anterior compartment of leg)
Describe the arterial supply of the ankle
Arterial supply via malleolar branches of the anterior tibial, posterior tibial and fibular arteries
Describe the innervation of the ankle joint
Innervation by tibial and deep fibular nerves
What is the subtalar joint?
The subtalar joint is a planar synovial joint formed from the articulation between two of the talus and calcaneus bones of the foot
Identify the articulating surfaces of the subtalar joint
- Inferior surface of the body of the talus
- Superior surface of the calcaneus
Identify the 3 ligaments which stabilise the subtalar joint
- Posterior talocalcaneal ligament
- Medial talocalcaneal ligament
- Lateral talocalcaneal ligament
An additional ligament is also found in the subtalar joint – the interosseous talocalcaneal ligament.
Describe its location and function
- Function: binds the talus and calcaneus together
- Location: lies within the sinus tarsi (a small cavity between the talus and calcaneus)
Identify the possible movements of the subtalar joint and the muscles involved
- Eversion — muscles of the lateral compartment of the leg
- Inversion – tibialis anterior muscle respectively
Describe the arterial supply of the subtalar joint
Arterial supply via posterior tibial and fibular arteries
Describe the innervation of the subtalar joint
- Plantar innervation – medial or lateral plantar nerve
- Dorsal innervation – deep fibular nerve
Identify the Ottawa Rules of when to X-ray an ankle fracture
- Tenderness over the medial malleolus
- Tenderness over the lateral malleolus
- Tenderness over navicular
- Tenderness over base of metatarsal
- Inability to bear weight
The ankle joint and the associated ligaments can be visualised as a ring in the coronal plane.
Identify and describe the borders of this ring
- Upper part – formed by articular surfaces of tibia & fibula
- Lower part – formed by subtalar joint
- Sides – formed by medial and lateral ligaments
In light of the ankle ring, discuss what is meant by stable and unstable ankle fractures
What is an ankle sprain?
- An ankle sprain is the partial/complete tear in the ligament of the ankle joint, occuring in a plantar-flexed weight bearing foot which is excessively inverted
- The lateral ligament is damaged as its weaker and resists inversion
What is a Pott’s Fracture-Dislocation?
A Pott’s fracture is a term used to describe a bimalleolar (medial & lateral malleoli) or trimalleolar (medial & lateral malleoli, distal tibia) fracture which occurs due to the force eversion of the foot
