2. To discuss…
The Mechanism of Injury
Types of Subtalar Dislocations
Therapeutic Approach
Prognosis
3. Simultaneous dislocation
Talocalcaneal and talonavicular joints
Four types described
Uncommon injury = 1 -2% of dislocations
Most published series = small number of patients
Occur in the 3rd decade of life
Men > women (6-10x more)
55% of medial and 72% of lateral dislocations have
associated injury
30% are irreducible by closed means
4. Mechanisms of Injury
High energy
MVA, falls from a height
68% of all dislocations with
trend toward open
Sports injury
“basketball foot”
Low energy
Tripping over a step
10% in the literature =
heavy selection bias?
Grantham SA. J Trauma. 1964.
5. Anatomy
Talus free of muscular
insertions and origins
Tendons encircle it
Ligamentous stability
Interosseous ligament =
majority
Deep deltoid and
calcaneofibular ligaments
7. Medial Dislocation
Most common = 80%
Inversion/rotation
Sustentaculum tali acts as a
fulcrum
Calcaneus displaced medially
“Acquired clubfoot deformity”
Barg A, et al. Foot Ankle Int. 2012
http://eorif.com/AnkleFoot/subtalar%20dis%20C1.html
8. Medial Dislocation
Rupture dorsal talonavicular ligament
Talus externally rotates
TNJ dislocation
Sinus tarsi widens
Interosseous ligament ruptures
Talocalcaneal joint ruptures anterior to
posterior
Heck BE, et al. Foot Ankle Int. 1996.
9. Lateral Dislocation
17% of all dislocations
High energy/eversion
Anterior calcaneal process
acts as a fulcrum
Foot appears
pronated/abducted
“Acquired flatfoot”
Toes plantarflexed
De Palma L, et al. Arch Orthop Trauma Surg. 2008.
Bibbo C, et al. Foot Ankle Int. 2003.
11. Posterior Dislocation
2% of all dislocations
Plantar hyper-flexion
Tearing of the interosseous
ligament
Sliding of talar head over
navicular
Very high instability
Convert to medial dislocation
Jungbluth P, et al. J Bone Joint Surg Am. 2010
12. Anterior Dislocation
< 1% of dislocations
Traction force/excessive
dorsiflexion
Tearing interosseous ligament
Sliding posterior facet beyond
calcaneal tuber
Very high instability
Convert to lateral dislocation
14. Physical Exam
Risk of skin necrosis
Medial dislocation
Lateral malleolus and
dorsolateral talar head
Lateral dislocation
Medial malleolus and
prominent medial talar head
Open dislocation = 20 – 40%
Bibbo C, et al. Foot Ankle Int.
2003:
88% had concomitant injuries
to the foot and ankle
Bryant J, Levis JT. West J Emerg Med. 2009.
15. Radiographs
AP view is most helpful
Talar head and navicular
Congruent
Lateral view
Medial dislocation
Talar head superior to
navicular
Lateral dislocation
Talar head inferiorly
displaced
De Palma L, et al. Arch Orthop Trauma Surg. 2008.
Pesce D, et al. J Emerg Med. 2011.
16. Bibbo C, et al. Foot Ankle Int. 2001:
9 cases in a 3 year period
Plain films diagnosed subtalar joint dislocation in all cases
5 associated injuries observed
CT identified additional injuries missed = 100%
Total of 13 new findings
44% of cases, new information changed treatment
Subtalar fusion (n=3), tarsal tunnel release, excision of bone
fragments
Bohay DR and Manoli A 2nd. Foot Ankle Int. 1996:
Occult intra-articular fractures identified on CT of 4 patients
“…invaluable tool to assess for associated
injuries in STJ dislocation, and should be
performed in all cases of STJ dislocation.”
Bibbo C, et al. Foot Ankle Int. 2001
17. Immediate closed reduction under sedation
Prevent additional soft tissue damage
Minimize neurovascular complications
How To:
Knee bent to relax gastrocnemius
Traction applied at heel
Counter-traction to thigh
Deformity accentuated
Medial dislocations = invert
Lateral dislocations = evert
Reverse with direct pressure over talar head and foot in
plantar flexion
18. Treatment
Bulky splint
Medial dislocations =
eversion
Lateral dislocations =
inversion
Non-weightbearing
4 to 6 weeks
Physical therapy program
Strengthening and ROM
Splint photo: Hsu RY, et al. Orthopedics. 2013.
19. Obstacles to Reduction
Medial Dislocation
“Buttonholing” of the talar
head through:
Extensor digitorum brevis
Extensor retinaculum
Talonavicular ligaments
Heck BE, et al. Foot Ankle
Int. 1996:
Cadaveric study did not
demonstrate
entrapment of EDB
Entrapment of deep
peroneal nerve
Heck BE, et al. Foot Ankle Int. 1996.
Wagner R, et al. Injury. 2004
20. Obstacles to Reduction
Lateral Dislocation
Posterior tibial tendon
Osteochondral fx fragments
TNJ or STJ
May act as bony block
Waldrop J, et al. Foot Ankle. 1992.
21. Medial Dislocation
Longitudinal anteromedial incision over talar head/neck
Lateral Dislocation
Longitudinal medial incision over talar head
Allows access to posterior tibial tendon
Disimpaction of talus and navicular
Small, loose fragments removed
Larger fragments fixed with k-wires or screws
Immobilization in SLC for 4 to 6 weeks
22. Between 20 – 40% are open dislocations
Milenkovic S, et al. Injury. 2006:
11 Gustilo II and III subtalar dislocations
Follow up 18 – 28 months
Outcome
Ex fix removed 4 – 6 weeks
No infection
Avascular necrosis = 1 (Gustilo IIIB medial dislocation)
7 associated fractures
Arthrosis = 8
Reduced ROM = 9
Pain with prolonged activity = 8
24. Acute
Skin necrosis
Nerve injury
Tibial nerve
Lateral dislocation
Medial plantar nerve
Medial dislocation
Chronic
Joint stiffness/ ROM
Arthritis
Chronic pain
Instability
Avascular necrosis of the talus
Reflex sympathetic dystrophy
Complications are more frequent in lateral dislocations
High trauma energy
Higher incidence of associated bone/osteochondral lesions
25. Factors
Time to reduction
Type of dislocation
Soft tissue damage
Duration of immobilization
Intra-articular fractures associated with poor prognosis
20% complication rate
Minimal disability despite subtalar motion loss
80% have restricted ROM
50 – 80% radiographic evidence of arthritis
Wagner R, et al. Injury. 2004
26. Prognosis: Open Dislocations
Goldner JL, et al. J bone Joint Surg
Am. 1995:
15 patients Gustilo Grade 3
I&D followed by reduction and
immobilization
Mean 18 year follow up
Associated injuries:
Tibial nerve injury = 10
PTT rupture = 5
PT artery laceration = 5
Articular fx = 12
Navicular fx = 3
Talar dome fx = 3
Malleolar fx = 3
Outcome
Osteonecrosis of the talus = 5
Triple arthrodesis = 4
Pantalar arthrodesis = 1
STJ arthrosis = 2
STJ arthrodesis = 2
All reported pain in ankle
Most had difficulty climbing
stairs and walking uneven ground
Wagner R, et al. Injury. 2004
27. Perugia D, et al. Int Orthop. 2002:
45 patients (37 medial and 8 lateral)
Mean follow up of 7.5 years (2-17 years)
Treatment
Closed reduction, SLC x 4 weeks, aggressive rehab
Outcome
Mean AOFAS score = 84
No significant difference between medial and lateral
Minimal or no limitation to activity
1 STJ arthrodesis due to chronic instability and pain
“…pure subtalar dislocation produced by low energy
trauma, promptly reduced and immobilized for four
weeks has a favorable long-term outcome.”
28. Jungbluth P, et al. J Bone Joint Surg Am. 2010:
23 patients (16 medial, 6 lateral, 1 posterior)
Mean follow up = 58.3 months
Treatment
13 closed reduced
7 open reduction with external fixation
NWB 6 weeks with progressive WB and aggressive PT
Full weight 10.6 weeks
Outcome
AOFAS Score
Closed = 83.3
Open = 80.9
Mean = 82.3
No differences observed between medial and lateral dislocations
No difference in ROM of affected and unaffected side
9 patients
Minor degenerative changes
No pain or restriction of movement
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