subtalar dislocations
TRANSCRIPT
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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