Yo, that subtalar joint looks gnarly! (subtalar dislocations)

HPI: 
Teenage male patient skating at high speed when his board abruptly came to a stop resulting in an inversion injury to his left ankle

PE: 
Skin intact

Left foot locked in supination with plantar flexion, obvious deformity to ankle

2+ DP/PT pulses, capillary refill < sec, SILT, 5/5 motor strength

 

Imaging: 
Medial subtalar dislocation: foot & calcaneus displaced medially, head of talus prominent dorsolaterally, navicular lies medial to talar head and neck

Lateral subtalar dislocation:  calcaneus displaced lateral to talus, talar head lies medially, navicular lies lateral to talar neck

Management:


·      Closed reduction-facilitated with knee flexion, relax gastrocnemius, may require sedation

·      Follow up CT scan ankle to assess for osteochondral lesions or fractures, assess reduction

·      Short leg cast/splint for 3-4 weeks

·      Approximately 10 % of medial dislocations and 20 % lateral require open reduction



Reduction Procedure:


https://www.youtube.com/watch?v=H6Dz566KrcM




 Anatomy: 
See attached

 Discussion:

·      Subtalar dislocation involves dislocation of distal articulations of talus at both talonavicular and talocalcaneal joints

·      Ankle joint undisturbed

·      Associated injuries: osteochondral lesions of talus, ankle fracture, fracture base of 5th metatarsal, navicular and cuboid fractures

·      Lateral dislocations less common, have more complications

Complications: infection (usually open), avascular necrosis (usually following fracture as talus is not disrupted from ankle mortoise and has blood supply).




     Key Points: 



·      Subtalar dislocations-medial more common than lateral, mechanism important part of HPI, clinical diagnosis

·      Obtain x rays to assess for associated injuries (ie fractures)

·      Manage with closed reduction and short leg cast/splint

·      10-20% may require open reduction

·      Obtain post reduction CT scan to assess reduction and osteochondral lesions/fractures

·      Complications rare but include infection (usually open) avascular necrosis ( usually associated fracture)