1. 
Subtalar Dislocations
Jennifer Gerres DPM, PGY-3

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

6. 
Types of Dislocation
Medial, Lateral, Posterior, and Anterior
Direction of the foot in relation to the talus

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.

10.  Rupture anterior bundles of deltoid ligament
 Interosseous ligament ruptures
 STJ dislocation
 Dorsal talonavicular ligament ruptures
 Talus externally rotates
 TNJ dislocation Waldrop J, et al. Foot Ankle. 1992.

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

13. 
Approach
Physical Exam, Ancillary Studies, Treatment

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

23. 
Prognosis

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

29. 
Conclusion

30.  Uncommon Injury = <2%
 88% have concomitant injuries to foot/ankle
 Prompt reduction is key
 CT invaluable tool
 Intra-articular fractures = worse prognosis

31. 
References

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36. 
ThankYou