Ankle Joint

Description

Coronal view of the ankle joint

Ankle radiograph labeled (mortise view)

Illustration of lateral view of ankle joint with ligaments, bones and tendons labeled

Anatomic illustration of the deltoid ligament and other medial ligaments of the foot and ankle

Name

• True Ankle Joint
• Talocrural Joint
• Mortise Joint
• Tibiotarsal joint

General

• Synovial joint of the lower limb
• Formed by articulation of tibia, fibula, talus
• Hinge type joint which permits dorsiflexion and plantarflexion
• To a lesser degree, pronation and supination
• Functions as a shock absorber during heel strike/ gait

Osseous Components

• Articular component of distal Fibula (Lateral Malleolus)
• Distal Tibia (Medial Malleolus)
• Trochlear dome of the Talus

Articulating Surfaces

• Mortise
  • The distal tibia and fibula are bound together by strong tibiofibular ligaments
  • Together they form a bracket shaped socket covered with hyaline cartilage
  • This is called the mortise
• Body of talus
  • Fits snugly into the mortise
  • It is wedge shaped, broad anteriorly, narrow posteriorly

Joint Capsule

• Attached to the margins of the articular surfaces of medial/lateral malleolus
• Distally, attached to margins of the talar trochlear surface
• Relatively thin, weak
• Strengthened by the medial/lateral ligaments
• Lined by a synovial membrane
• Projects from distal tibiofibular joint up to interosseous tibiofibular ligament

Medial view of the ankle joint presenting the contents of the tarsal tunnel; tibialis posterior tendon (TP), flexor digitorum longus tendon (FDL), posterior tibial artery (PTA), posterior tibial vein (PTV), tibial nerve (TN) and the tendon of flexor hallucis longus (FHL), deep to the flexor retinaculum (FR). The bifurcation (B) points of the PTA (PTA B) and TN (TN B) are also represented

Ligaments

• Deltoid Ligament
  • Attachs the medial malleolus to the talus
  • Composed of several individual superficial and deep ligaments
  • Function is to resist over-eversion of the foot
• Lateral Ankle Ligament Complex
  • Attaches the lateral malleolus to the talus, calcaneus
  • Anterior Talofibular Ligament
  • Calcaneofibular Ligament
  • Posterior Talofibular Ligament

Ankle Ring

• Can be visualized as a ring in the coronal field
• Upper ring: articular surface of tibia, fibula
• Lower ring: subtalar joint
• Sides: formed by the medial and lateral ligaments

Movement

• General
  • Hinge type joint with movement in one plane
  • Approx 30-50° of plantar flexion, about 20° of dorsiflexion
• Axis of motion is rotated laterally 20–30°, inclined downward 10°
  • Occurs because fibular malleolus extends more distally and posteriorly than the tibial malleoli
• Axis of motion is rotated laterally 20–30°, inclined downward 10°
  • Occurs because fibular malleolus extends more distally and posteriorly than the tibial malleoli
• Dorsiflexion
  • Muscles: gastrocnemius, soleus, plantaris, posterior tibialis
  • Anterior part of the talus is held in the mortise, joint is more stable
• Plantarflexion
  • Muscles: tibialis anterior, extensor hallucis longus, extensor digitorum longus
  • Posterior part of the talus is held in the mortise, joint is less stable
• Supination: plantarflexion, adduction, inversion
  • Inversion: tibialis anterior, posterior tibialis
• Pronation: dorsiflexion, abduction, eversion
  • Eversion: Fibularis longus, fibularis tertius, fibularis brevis

Illustration of the ankle bones

Normal mortise radiograph of the ankle showing the articular components of the distal fibula, tibia and talus

Vascular Supply

• Malleolar branches of
  • Anterior Tibial Artery
  • Posterior Tibial Artery
  • Fibular Artery

Innervation

• Branches of
  • Tibial Nerve
  • Superficial Fibular Nerve
  • Deep Fibular Nerve

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Clinical Significance

• Medial Ankle Sprain
• Lateral Ankle Sprain
• Ankle Fracture
• Talus Fracture
• Syndesmotic Sprain
• Chronic Ankle Instability
• Ankle Osteoarthritis
• Osteochondral Defect Talus

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See Also

• Ankle Pain Main
• Ankle Anatomy Main
• Physical Exam Ankle

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