Subtalar Dislocation

Subtalar dislocation is the dislocation of the talonavicular and talocalcaneal joints without any associated fractures. Calcaneus and the rest foot dislocate medially, laterally, posteriorly or anteriorly in relation to the talus.

Isolated subtalar dislocations are unusual injuries due to the inherent instability of the talus. Subtalar dislocations are frequently associated with fractures of the malleoli, the talus, the calcaneus or the fifth metatarsal. Four types of subtalar dislocation have been described according to the direction of the foot in relation to the talus: medial, lateral posterior and anterior. It has been shown that some of these dislocations may spontaneously reduce.

Other Names

  • Subtalar dislocation
  • Talocalcaneal joint dislocation
  • Talonavicular joint dislocation
  • Total talar dislocation
  • Extrusion of the talus
  • Pan-talar dislocation

Description

  • Luxatio tali totalis
  • This page refers to hindfoot dislocations of the Talocalcaneal Joint and Talonavicular Joint
    • Commonly referred to as a ‘subtalar dislocation’
    • This injury should not be confused with an Ankle Dislocation
  • Subtalar dislocations make up 1-2% of all dislocations (need citation)
  • Represent 1% of all traumatic injuries to the foot
  • Associated with
    • 46-83% of case are open, depending on reference material
    • Up to 44% have fractures (need citation)
Medial subtalar dislocation
  • Definition of subtalar dislocation
    • Disruption of articulation of the Talus to the Calcaneus
    • Simultaneous dislocation of the talocalcaneal and talo-navicular joints
    • Absence of tibio-talar or talar neck associated fractures

Mechanism of Injury

Medial subtalar dislocations result from forced inversion force applied to a plantarflexed foot, during this position the neck of the talus will hing and rotate around the sustentaculum tali as a pivot and this will cause a rupture of the lateral talonavicular joint capsule and ligaments, followed by the subtalar ligaments. Fracture of the posterior process of the talus is common to occur with medial disa locations.

Lateral subtalar dislocations result from forced eversion of a dorsiflexed foot during high-energy trauma, during this position the head of the talus rotates around the anterior process of the calcaneus, this will result in rupture of talonavicular and subtalar ligaments and joint capsules. Partial or complete rupture of the deltoid ligament may be presented with this injury because of the high-energy trauma.

Posterior subtalar dislocations result from forced plantar flexion of the foot.

Anterior subtalar dislocations result from anterior traction to the foot when the leg is in a fixed position. It is rare to find obvious foot deformity with posterior or anterior subtalar dislocations.

Causes

  • High energy
    • Most common
    • Examples include Motor vehicle accident, fall from height
  • Low energy
    • Less common
    • Can occur during sports or twisting injuries of the foot

Direction of dislocation

  • Medial (80–85%)[7]
  • Lateral (15–20%)[8]
    • More likely to have soft tissue, osseous injuries
    • More likely to require open reduction
    • Neurovascular injuries have been identified in up to 70 % of cases[9]
  • Posterior (2.5%)
  • Anterior (1%)
  • Total talar dislocation
    • tri-articular dislocation of talus at the tibiotalar, talonavicular and subtalar joints

Associated Conditions

  • Talus Fracture
  • Distal Fibula Fracture
  • Distal Tibia Fracture
  • Fifth Metatarsal Fracture
  • Calcaneus Fracture
  • Navicular Fracture

Pathoanatomy

  • Subtalar Joint
    • Formed by the talus superiorly, the calcaneus and navicular inferiorly
    • Posterior chamber: Talocalcaneal Joint
    • Anterior chamber: Talocalcanealnavicular Join

Differential Diagnosis

  • Fractures & Dislocations
    • Distal Tibia Fracture
    • Distal Fibular Fracture
    • Talus Fracture
    • Calcaneus Fracture
    • Subtalar Dislocation
    • Ankle Fracture (& Dislocation)
    • Peroneal Subluxation
  • Muscle and Tendon Injuries
    • Peroneal Tendon Injuries
    • Achilles Tendonitis
    • Achilles Tendon Rupture
    • Posterior Tibial Tendon Dysfunction
    • Flexor Hallucis Longus Tendinopathy
  • Ligament Injuries
    • Lateral Ankle Sprain
    • Medial Ankle Sprain
    • Syndesmotic Sprain
    • Chronic Ankle Instability
    • Intersection Syndrome Foot
  • Bursopathies
    • Retrocalcaneal Bursitis
  • Nerve Injuries
    • Peroneal Nerve Injury
    • Tarsal Tunnel Syndrome
  • Arthropathies
    • Osteoarthritis of the Ankle
    • Osteochondral Defect Talus
  • Pediatrics
    • Fifth Metatarsal Apophysitis (Iselin’s Disease)
    • Calcaneal Apophysitis (Sever’s Disease)
  • Other
    • Haglunds Deformity
    • Posterior Ankle Impingement Syndrome
    • Sinus Tarsi Syndrome

Diagnosis

  • History
    • Patients should be able to describe their injury pattern
    • Will endorse ankle/ foot pain, swelling, deformity
    • Inability to ambulate
  • Physical Exam
    • Gross deformity of the ankle
    • Soft tissue injury may or may not be present (i.e. open/closed)
    • Locked in supination with medial dislocation, pronation with lateral dislocation
  • Special Tests

Radiographs

  • Standard Radiographs Ankle
    • Also consider Standard Radiographs Calcaneus
  • Medial dislocation
    • Talar head superior to navicular on lateral view
  • Lateral dislocation
    • Talar head is colinear or inferior to navicular on lateral view

CT

  • Should be obtained after reduction
  • Helpful to
    • confirm adequate reduction
    • Exclude associated lesions

MRI

  • Role in subtalar dislocation is not well described
  • May be helpful to evaluate the soft tissues

Classification

  • Description
    • Based on position of foot relative to talus at the time of injury[3]
  • Medial dislocation
    • Foot: plantarflexed and inverted followed by an external rotation to the talus
    • Foot is locked in supination
  • Lateral dislocation
    • Foot: foot is everted on plantarflexed foot at the time of injury
    • The foot is locked in pronation
    • More likely to be open
  • Anterior and Posterior dislocation
    • Foot: pulls the foot in forced plantarflexion or translates it in an anterior direction
  • Total dislocation
    • Complete dislocation of talus from ankle, subtalar, talonavicular joints
    • Usually open

Treatment

Acute

  • Follow ATLS algorithm as needed depending on the mechanism of injury
  • Closed Reduction
    • Should be performed emergently, typically in ED (or OR)
    • Under procedural sedation (or general anesthesia)
    • Keep knee flexed to relax calf muscles
    • Immobilization with Posterior Short Leg Splint with Stirrup or Short Leg Cast with bilvalve
  • Approximately 32% require open reduction (need citation)

Nonoperative

  • Indications
    • Roughly 60-70% of cases
  • Immobilize
    • With Posterior Short Leg Splint with Stirrup or Short Leg Cast with bilvalve
    • Duration is typically 4-6 weeks
  • Non weight bearing (NWB)
    • Some authors recommend complete NWB during the entire period of immobilization
  • Physical Therapy

Operative

  • Indications
    • Instability
    • Associated injuries
    • Irreducible with closed reduction
    • Open dislocations
    • Failure of closed reduction
  • Technique
    • Stabilization with K wires
    • External fixation