questions
6

Subtalar Dislocations

Topic updated on 08/09/15 7:50pm
Introduction
  • Typically from a high-energy mechanism
    • 25% may be open 
      • lateral dislocations more likely to be open
    • 65% to 80% are medial dislocations
    • remaining are lateral dislocations
    • case reports of anterior or posterior dislocations
  • Associated injuries
    • associated dislocations 
      • talonavicular
    • associated fractures (up to 44%) 
      • with medial dislocation
        • dorsomedial talar head 
        • posterior process of talus  
        • navicular 
      • with lateral dislocation
        • cuboid 
        • anterior calcaneus 
        • lateral process of talus 
        • fibula 
Presentation
  • Physical exam
    • foot will be locked in supination with medial dislocation 
    • foot will be locked in pronation with lateral dislocation 
Imaging
  • Radiographs
    • medial subtalar dislocation 
      • talar head will be superior to navicular on lateral image 
    • lateral subtalar dislocation
      • talar head will be colinear or inferior to navicular on lateral image 
  • CT scan
    • perform following reduction
    • look for associated injuries or subtalar debris 
Treatment
  • Nonoperative
    • closed reduction and short leg non-weight bearing cast for 4-6 weeks
      • indications
        • first line of treatment
        • 60-70% can be reduced by closed methods
      • technique
        • requires adequate sedation
        • typical maneuvers include knee flexion and ankle plantar flexion
        • followed by distraction and hindfoot inversion or eversion depending on direction of dislocation
        • perform a post-reduction CT to look for associated injuries
  • Operative
    • open reduction
      • indications
        • failure of closed reduction Shows incidence, mechanism and treatment of subtalar dislocations
          • up to 32% require open reduction
          • medial dislocation reduction blocked by lateral structures including
            • peroneal tendons
            • extensor digitorum brevis 
            • talonavicular joint capsule
          • lateral dislocation reduction blocked by medial structures including
            • posterior tibialis tendon  
            • flexor hallucis longus
            • flexor digitorum longus
          • place temporary transarticular pins as needed if joint remains unstable
Complications
  • Post-traumatic Arthritis
    • long-term follow up of these injuries show degenerative changes 
      • Subtalar joint most commonly affected with up to 89% of patients demonstrating radiographic arthrosis (63% symptomatic)

 

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Qbank (6 Questions)

TAG
(OBQ12.150) Which of the following is true when comparing Figure A to Figure B? Topic Review Topic
FIGURES: A   B        

1. Figure B is more likely to have an associated fracture
2. Figure A is more likely to be blocked from closed reduction by the extensor digitorum brevis
3. FIgure A is more likely to be open
4. FIgure B is more likely to be blocked from closed reduction by the posterior tibial tendon
5. Figure A more likely to be stable following closed reduction

PREFERRED RESPONSE ▶
TAG
(OBQ09.76) A 34-year-old male falls 10 feet from a balcony and is brought to the emergency room with the deformity seen in Figure A. Radiographs shown are shown in Figure B and C. Which of the following structures can block closed reduction of this injury pattern? Topic Review Topic
FIGURES: A   B   C      

1. Flexor hallucis longus tendon
2. Extensor digitorum brevis muscle
3. Posterior tibial tendon
4. Tibialis anterior tendon
5. Plantar fascia

PREFERRED RESPONSE ▶
TAG
(OBQ09.123) A 37-year-old female sustains the injury seen in Figures A and B. At long-term follow up, degeneration of which of the following joints has been shown to have the highest rate of patient symptoms? Topic Review Topic
FIGURES: A   B        

1. Tibiotalar joint
2. Talonavicular joint
3. Calcaneocuboid joint
4. Lisfranc joint
5. Subtalar joint

PREFERRED RESPONSE ▶
TAG
(OBQ08.216) A 30-year-old male falls off the roof and sustains the injury seen in Figure A. Multiple attempts at a closed reduction are made, but are unsuccessful. Entrapment of which of the following structures is the most likely etiology? Topic Review Topic
FIGURES: A          

1. Peroneal tendons
2. Posterior tibial tendon
3. Extensor retinaculum
4. Anterior tibial tendon
5. Flexor hallucis longus

PREFERRED RESPONSE ▶
TAG
(OBQ04.153) A 40-year-old male suffers the isolated injury shown in figure A with no associated fractures. What joint is dislocated in this radiograph? Topic Review Topic
FIGURES: A          

1. Tibiotalar
2. Talonavicular
3. Calcaneocuboid
4. First metatarsophalangeal
5. First tarsometatarsal

PREFERRED RESPONSE ▶
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