Introduction Epidemiology incidence rare accounts for 1% of all dislocations demographics more common in young or middle-aged males Pathophysiology typically result from a high-energy mechanism 25% may be open lateral dislocations more likely to be open Associated conditions 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 Prognosis post-traumatic arthritis is common poorer outcomes associated with high-energy mechanisms lateral dislocations result from higher energy mechanisms open dislocations high risk of infection due to lack of muscle coverage poor vascularity of soft tissues difficulty cleaning contaminated joints concomitant fractures involving the subtalar joint Anatomy Articulation inferior surface articulates with posterior facet of calcaneus talar head articulates with navicular bone sustenaculum tali lateral process articulates with posterior facet of calcaneus lateral malleolus of fibula posterior process consist of medial and lateral tubercles separated by groove for FHL Muscles talus has no muscular or tendinous attachments Blood Supply posterior tibial artery via artery of tarsal canal (most important and main supply) supplies most of talar body via calcaneal braches supplies posterior talus anterior tibial artery supplies head and neck perforating peroneal arteries via artery of tarsal sinus supplies head and neck deltoid artery (located in deep segment of deltoid ligament) supplies body may be only remaining blood supply with a talar neck fracture Classification Anatomic medial dislocation most common (65-80%) due to lateral malleolus acting as strong buttress, preventing lateral dislocation results from inversion force on plantarflexed foot sustentaculum tali acts as fulcrum for the neck of the talus to pivot around foot becomes locked in supination associated with posterior process of talus, dorsomedial talar head, and navicular fractures reduction blocked by peroneal tendons, EDB, talonavicular joint capsule lateral dislocation more likely to be open results from eversion force on plantarflexed foot anterior process of calcaneus acts as fulcrum for the anterolateral corner of the talus to pivot around foot becomes locked in pronation associated with lateral process of talus, anterior calcaneus, cuboid, and fibula fractures reduction blocked by PT tendon, FHL, FDL anterior dislocation rare posterior dislocation rare total dislocation (extruded talus) talus is completely dislocated from ankle and subtalar and talonavicular joints results from continuation of forces required for medial or lateral dislocation with disruption of talocrural ligaments and extrusion of talus from ankle joint usually open Presentation Physical exam foot will be locked in supination with medial dislocation known as "acquired clubfoot" foot will be locked in pronation with lateral dislocation known as "acquired flatfoot" Imaging Radiographs recommended views AP lateral findings medial dislocation talar head will be superior to navicular on lateral view lateral dislocation talar head will be collinear or inferior to navicular on lateral view CT scan indications perform following reduction findings 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 Operative open reduction indications open dislocations failure of closed reduction 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 is the most common flexor hallucis longus flexor digitorum longus Techniques Closed reduction sedation requires adequate sedation reduction typical maneuvers include knee flexion and ankle plantarflexion followed by distraction and hindfoot inversion or eversion depending on direction of dislocation post-reduction perform a post-reduction CT to look for associated injuries Open reduction anesthesia approach dictated by direction of dislocation and associated fractures medial dislocation sinus tarsi approach to remove incarcerated lateral structures (EDB, etc.) lateral dislocation medial approach between tibialis anterior and posterior tibial tendon to remove medial structures (posterior tibialis tendon, etc.) may still require sinus tarsi/lateral approach to remove subtalar debris post-op care if joint stable place in short leg cast with non-weightbearing for 4-6 weeks if joint remains unstable place temporary transarticular pins or spanning external fixator 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) Stiffness most common complication
QUESTIONS 1 of 6 1 2 3 4 5 6 Previous Next (OBQ08.175) What is the most common fracture associated with a lateral subtalar dislocation? Review Topic QID: 561 1 Distal fibular fracture 28% (587/2133) 2 Cuboid fracture 29% (628/2133) 3 Calcaneus fracture 8% (179/2133) 4 Talus fracture 28% (601/2133) 5 Navicular fracture 6% (120/2133) ML 5 Select Answer to see Preferred Response PREFERRED RESPONSE 2 (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? Review Topic QID: 2936 FIGURES: A B 1 Tibiotalar joint 6% (44/761) 2 Talonavicular joint 12% (90/761) 3 Calcaneocuboid joint 1% (11/761) 4 Lisfranc joint 9% (66/761) 5 Subtalar joint 71% (541/761) ML 2 Select Answer to see Preferred Response PREFERRED RESPONSE 5 (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? Review Topic QID: 602 FIGURES: A 1 Peroneal tendons 20% (503/2454) 2 Posterior tibial tendon 60% (1476/2454) 3 Extensor retinaculum 2% (53/2454) 4 Anterior tibial tendon 3% (62/2454) 5 Flexor hallucis longus 14% (349/2454) ML 3 Select Answer to see Preferred Response PREFERRED RESPONSE 2 (OBQ12.150) Which of the following is true when comparing Figure A to Figure B? Review Topic QID: 4510 FIGURES: A B 1 Figure B is more likely to have an associated fracture 8% (466/5677) 2 Figure A is more likely to be blocked from closed reduction by the extensor digitorum brevis 12% (676/5677) 3 FIgure A is more likely to be open 54% (3071/5677) 4 FIgure B is more likely to be blocked from closed reduction by the posterior tibial tendon 19% (1082/5677) 5 Figure A more likely to be stable following closed reduction 6% (325/5677) ML 4 Select Answer to see Preferred Response PREFERRED RESPONSE 3 (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? Review Topic QID: 2889 FIGURES: A B C 1 Flexor hallucis longus tendon 12% (438/3698) 2 Extensor digitorum brevis muscle 62% (2296/3698) 3 Posterior tibial tendon 20% (752/3698) 4 Tibialis anterior tendon 5% (182/3698) 5 Plantar fascia 0% (13/3698) ML 3 Select Answer to see Preferred Response PREFERRED RESPONSE 2 (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? Review Topic QID: 1258 FIGURES: A 1 Tibiotalar 1% (10/959) 2 Talonavicular 95% (911/959) 3 Calcaneocuboid 3% (32/959) 4 First metatarsophalangeal 0% (2/959) 5 First tarsometatarsal 0% (1/959) ML 1 Select Answer to see Preferred Response PREFERRED RESPONSE 2
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