Figures A through C show a medial subtalar dislocation. Irreducible dislocations are typically the result of either inadequate sedation or interposed soft tissue structures. In medial dislocations, the extensor digitorum brevis, the deep peroneal neurovascular bundle, or the joint capsule may block a closed reduction.
Bibbo et al found that subtalar dislocations were irreducible 32% of the time and that 88% had ipsilateral foot and ankle injuries. At follow up, 89% of patients demonstrated radiographic changes of the subtalar joint, and had worse function on the side of the subtalar dislocation as demonstrated by lower AOFAS scores.
Answer 1. The flexor hallucis longus tendon may be a block to closed reduction for lateral subtalar dislocations
Answer 3. The posterior tibial tendon may be a block to reduction for lateral subtalar dislocations
Answer 4. The tibialis anterior tendon does not commonly preclude closed reduction of a subtalar dislocation
Answer 5. The plantar fascia does not block closed reduction of the subtalar joint
Fischgrund JS (ed): Orthopaedic Knowledge Update 9. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2008, pp 493-509
Bibbo C, Anderson RB, Davis WH. Injury characteristics and the clinical outcome of subtalar dislocations: a clinical and radiographic analysis of 25 cases. Foot Ankle Int. 2003 Feb;24(2):158-63.
PMID:12627624 (Link to Abstract)