Subtalar DislocationsJennifer Gerres DPM, PGY-3

Objectives

To discuss… The Mechanism of Injury Types of Subtalar Dislocations Therapeutic Approach Prognosis

Introduction

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

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.

Anatomy

Talus free of muscular insertions and origins Tendons encircle it

Ligamentous stability Interosseous ligament =

majority Deep deltoid and

calcaneofibular ligaments

Types of DislocationMedial, Lateral, Posterior, and Anterior

Direction of the foot in relation to the talus

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. 2012http://eorif.com/AnkleFoot/subtalar%20dis%20C1.html

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.

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.

Lateral Dislocation

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.

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

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

ApproachPhysical Exam, Ancillary Studies, Treatment

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.

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.

CT Scan

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

Treatment

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

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.

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

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.

Open Treatment

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

External Fixation

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

Prognosis

Complications

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 dislocationsHigh trauma energyHigher incidence of associated bone/osteochondral lesions

Prognosis

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

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

OutcomeOsteonecrosis of the talus

= 5Triple

arthrodesis = 4Pantalar

arthrodesis = 1STJ 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

Prognosis: Closed Dislocations

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.”

Prognosis: Closed Dislocations

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

OutcomeAOFAS Score

Closed = 83.3Open = 80.9Mean = 82.3

No differences observed between medial and lateral dislocationsNo difference in ROM of affected and unaffected side 9 patients

Minor degenerative changes No pain or restriction of movement

Conclusion

Subtalar Dislocations…

Uncommon Injury = <2%

88% have concomitant injuries to foot/ankle

Prompt reduction is key

CT invaluable tool

Intra-articular fractures = worse prognosis

References

References

Barg A, Tochigi Y, Amendola A, Phisitkul P, Hintermann B, Saltzmann CL. Subtalar instability: diagnosis and treatment. Foot Ankle Int. 2012; 33(2):151-160.

Bibbo C, Lin SS, Abidi N, Berberian W, Grossman M, Gebauer G, Behren FF. Missed and associated injuries after subtalar dislocation: the role of ct. Foot Ankle Int. 2001; 22(4):324-328.

Bibbo C, Robert B, Anderson RB, Hodges W, Davis WH. Injury characteristics and the clinical outcome of subtalar dislocations: a clinical and radiographic analysis of 25 cases. Foot Ankle Int. 2003; 24(2)158-163.

Bohay DR, Manoli A II. Occult fractures following subtalar joint injuries. Foot Ankle Int. 1996; 17(3):164-169.

Bohay DR, Manoli A II. Subtalar joint dislocations. Foot Ankle Int. 1995; 16(12):803-808.

Conesa X, Barro V, Barastegui D, Batalla L, Tomas J, Molero V. Lateral subtalar dislocation associated with bimalleolar fracture: case report and literature review. J Foot Ankle Surg. 2011; 50(5):612-615.

References

DeLee JC, Curtis R. Subtalar dislocation of the foot. J Bone Joint Surg Am. 1982; 64(3):433-437.

de Palma L, Santucci A, Marinelli M. Irreducible isolated subtalar dislocation: a case report. Foot Ankle Int. 2008; 29(5): 523-526.

Goldner JL, Poletti SC, Gates HS III, Richardson WJ. Severe open subtalar dislocations. Long-term results. J Bone Joint Surg Am. 1995; 77(7):1075-1079.

Heck BE, Ebraheim NA, Jackson WT. Anatomical considerations of irreducible medial subtalar dislocation. Foot Ankle Int. 1996; 17(2):103-106.

Horning J, DiPretaJ. Subtalar Dislocation. Orthopedics. 2009; 32(12):904-908.

Hyder N, Jones S, Nair B. Medial subtalar dislocation. The Foot. 1997; 7:34-36.

Jungbluth P, Wild M, Hakimi M, Gehrmann S, Djurisic M, Windolf J, Muhr G, Kälicke T. Isolated subtalar dislocation. J Bone Joint Surg Am. 2010; 92:890-894.

References

Lasanianos NG, Lyras DN, Mouzopoulos G, Tsutseos N, Garnavos C. Early mobilization after uncomplicated medial subtalar dislocation provides successful functional results. J Orthop Traumatol. 2011: 12(1):37-43.

Love JN, Dhindsa HS, Hayden DK. Subtalar dislocation: evaluation and management in the emergency department. J Emer Med. 1995; 13(6):787-793.

Merchan ECR. Subtalar dislocations: long-term follow-up of 39 cases. Injury. 1992; 23(2):97-100.

Milenkovic S, Mitkovic M, Bumbasirevi. External fixation of open subtalar dislocation. Injury. 2006; 37(9): 909-913.

Perugia D, Basile A, Massoni C, Gumina S, Rossi F, Ferretti A. Conservative treatment of subtalar dislocations. Int Orthop. 2002; 26(1):56-60.

References

Pesce D, Wethern J, Patel P. Rare case of medial subtalar dislocation from a low-velocity mechanism. J Emer Med. 2008; 41(6):121-124.

Sanders DW. Fractures of the talus. In: Bucholz RW, Heckman JD, Court-Brown C, eds. Rockwood and Green’s Fractures in Adults. Vol 1. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2006:2249-2292.

Tucker DJ, Burian G, Boylan J. Lateral subtalar dislocation: review of the literature and case presentation. J Foot Ankle Surg. 1998; 37(3):239-247.

Wagner R, Blattert TR, Weckbach A. Talar dislocations. Injury. 2004; 35(Suppl2):SB36-45.

Waldrop J, Ebraheim NA, Shapiro P, Jackson WT. Anatomical considerations of posterior tibialis tendon entrapment in irreducible lateral subtalar dislocation. Foot Ankle. 1992; 13(8):458-461.

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