Fractures of the Talus and Subtalar Dislocations

David Sanders MD, MSc, FRCSC

London Health Sciences CentreUniversity of Western Ontario London, Ontario, Canada

Created March 2004; Revised August 2006Revised May 2011

Fractures of the Talus and Subtalar Dislocations

Outline:

Talar Neck Fractures• Anatomy• Incidence• Imaging• Classification• Management• Complications

Talar body, head and process fractures

Subtalar dislocations• Classification• Management • Outcomes

• Surface 60% cartilage

• No muscular insertions

Anatomy

Blood Supply

4 primary arterial sources:

• Artery of tarsal canal• Artery of tarsal sinus• Dorsal neck vessels• Deltoid branches

mediallateral

Inferior view of talus, showing vascular anastomosis

Vascularity

• Artery of tarsal canal supplies majority of talar body

Side ViewTop ViewDeltoid Branches

Posterior tuberclevessels

Artery of TarsalSinus

Artery ofTarsal Canal

Superior Neck Vessels

Superior Neck Vessels

Artery of TarsalSinus

Artery ofTarsal Canal

Posterior tuberclevessels

Talus ORIF Technique

Vascularity

Incidence

• 2 % of all fractures

• 6-8% of foot fractures

• High complication rates• avascular necrosis

• post-traumatic arthritis

• malunion

Mechanism of Injury

• Hyperdorsiflexion of the foot on the leg

• Neck of talus impinges against anterior distal tibia, causing neck fracture

• If force continues:• talar body dislocates posteromedial

• often around deltoid ligament

Injury Mechanism

• Previously called “aviator’s astragalus”

• Usually due to motor vehicle accident or falls from height

• Approximately 50 % of patients have multiple traumatic injuries

Biomechanics

• Theoretical shear force across talar neck:• 1200 N during active motion

[Swanson 1992]

Fracture fixation must withstand this force to permit active motion in the postoperative phase

Imaging• Complex 3-D structure• Multiple plain film orientations:• AP, Lateral, Broden, & mortise

views demonstrates joint congruity of ankle and subtalar joint

• Canale view for longitudinal alignment: approximately 15° IR to get calcaneous out of view

Canale View

Canale View

• Slight ankle plantarflexion with knee bent to rest foot on the table

• 15 degree pronation

• Xray Tube • 15 degree from vertical

Canale View

CT Scan

• Most useful assessment tool for surgical planning

• Confirms displacement• Demonstrates subtalar joint

reduction, comminution, osteochondral fractures/debris

MRI Scan

• Primary role in talus injuries is to assess complications, especially avascular necrosis

• May be poor quality if extensive hardware present

Zone of osteonecrosis following distribution of Artery of Tarsal Canal

Talar Neck Fractures: Classification

• Hawkins, 1970

• Predictive of AVN rate

• Widely used


Hawkins ClassificationHawkins, LR, JBJS, 52A: 991, 1970

I) Nondisplaced<10%

II) Subtalar Displacement

<40%

III) Subtalar & TC~90%

IV) *Pantalar100%

*Canale, ST, JBJS, 60A: 143, 1978

Hawkins 1

• Type I: undisplaced• AVN rate 0 – 13 %

• Uncommon as most talar neck fractures are displaced

Hawkins 2

• Displaced fracture with subtalar subluxation / dislocation

• A) fracture line enters subtalar joint

• B) subtalar joint intact

• AVN 20 – 50 %

• Most common type

Hawkins 3

• Subtalar and ankle joint dislocated

• Talar body extrudes, usually around deltoid ligament

• Commonly open fractures, reduction very difficult• Closed: plantar flex foot & flex

knee• Open: joy sticks

• AVN 83 – 100 %

Hawkins 4

• Added to classification by Canale, 1974

• Incorporates talonavicular subluxation

• Rare variant

• Complex talar neck fractures which otherwise do not fit classification are included as Type 4 injuries

Classification:

• Comminution:

• An important additional predictor of results, especially regarding prognosis re:• Malunion

• Subtalar joint arthritis

• Included in AO-OTA classification as a modifier

Goals of Management

• Immediate reduction of dislocated joints• Vascularity

• Cutaneous tension

• Vascular compromise

• Anatomic fracture reduction

• Stable fixation

• Facilitate union

• Avoid complications


Definitive Treatment• Prompt anatomic operative reduction

• “die is cast” with injury• Use “joy stick” K-wires for reduction• Articular bone affects ROM (V, Sup, PF)

• Maintenance of reduction with HW• Screws (AP, PA), countersink• Plates (2.0 mini condylar or T)

• Dual incisions• Do not dissect capsular attachments• Maintain as much soft tissue attachments

Treatment of Talar Neck Fractures• Emergent reduction of dislocated joints

• Stable internal fixation

• Debridement of subtalar joint

• Maintain as much soft tissue/vascular attachments

• Choice of fixation and approach depends upon personality of fracture

Treatment of Talar Neck Fractures

• Post operative rehabilitation:

• Sample protocol:• Initial immobilization, 2-6 weeks depending upon soft

tissue injury and patient factors, to prevent contractures and facilitate healing

• Non weight-bearing, Range of Motion therapy until 3 months or fracture union

Hawkins I Fracture

Options:

• Non Operative & Non-Weight-Bearing Cast for 4-6 weeks followed by removable brace and motion

OR:

• Percutaneous screw fixation and early motion

Hawkins II, III, and IV Fractures:

• Results dependent upon development of complications

• Osteonecrosis

• Malunion

• Arthritis

Case Example

• 29 yo male

• ATV rollover

• Isolated injury LLE

• These injury films are tough to interpret, but close review demonstrates the dislocated talar body with some comminution.

Diagnosis

• “Hawkins’ 3” talar neck fracture

• Associated comminution, probably involving medial column and subtalar joint

Controversies for this Case:

• Surgical timing

• Closed reduction

• Surgical approach

• Fixation

Surgical Timing

• In general: emergent reduction of dislocated joints

• Allow life threatening injuries to take priority and resuscitate adequately first

Closed Reduction?

• May be very useful, particularly if other life threatening injuries preclude definitive surgery

• Difficult in Hawkins’ 3 and 4 injuries

Closed Reduction Technique:

• Adequate sedation

• Flex knee to relax gastrocs

• Traction on plantar flexed forefoot to realign head with body

• Varus/valgus correction as necessary

• Direct pressure on talar body

• Adjunct: traction pin, general anesthetic, etc

• Avoid repetitive reduction attempts in order to avoid skin compromise or tearing

Closed Reduction Example

External Fixation

• Limited roles:• Multiply injured patient with

talar neck fracture in whom definitive surgery will be delayed

• Temporizing measure to stabilize reduced joints

• Construct bridges tibia – calcaneus – midfoot

Surgical Approaches: Options

• 1 incision techniques:• Anteromedial or

• Anterolateral

• Problem: difficult to visualize the entire talar neck and subtalar joint without significant soft tissue stripping and devascularization

• Problem: usual medial comminution inhibits accurate read of fracture reduction

Surgical Approaches: Options

• 2 incision technique: (generally preferred)• Anteromedial and lateral/anterolateral

• Problem: 2 skin incisions, close together

• Benefit: excellent fracture visualization at critical sites of reduction and subtalar joint with less stripping

1st Approach: Anteromedial

• Medial to TibAnt• Make incision more

posterior for talar body fractures to facilitate medial malleolar osteotomy

1st Approach: Anteromedial

• Provides view of neck alignment and medial comminution

• Extend incision distally to talonavicular joint – hardware is placed distal to proximal and needs to be well countersunk to avoid impingement

2nd Approach: Lateral

• Tip of Fibula directly anterior

• Mobilize EDB as sleeve

• Protect sinus tarsi contents

2nd Approach: Lateral

• Visualizes Anterolateral alignment and subtalar joint

• Facilitates Placement of “Shoulder Screw” or lateral plate

2 incisions: Skin bridge

• Narrow skin bridge but generally well tolerated

• Talus fractures generally have less soft tissue problems compared to plafond or calcaneus fractures

Fixation Options

• Stable Fixation to allow early motion is the goal

• 1200 N stress across talar neck during early motion (Swanson JBJS 1992)

• That is a lot of force! 2 A to P screws only resists about 1 kN of stress so need more fixation

Surgical Tactics: Fixation

• Anterior• Partial threaded screws

• Fully threaded screws

• Mini-fragment plates (2.0, 2.4 mm)

• Posterior• Lag screws Implant selection

depends upon injury, degree of comminution, bone quality

Posterior to Anterior Fixation:• Screw fixation stronger from posterior than

from anteromedial (T Bray)

• Screws perpendicular to fracture site

• 2 PA screws in compression are able to withstand the theoretical shear force of active motion

• Avoid excessive posterior capsular stripping

• Creates potentially 3 incisions• (posterior, medial, lateral)

90°

Anterior Screw Fixation:

Screw fixation alone is acceptable for non-comminuted fractures, but consider adding a plate if there is comminution. • Easy to insert under direct

visualization

• This example: displaced type 2: 4 A-P screws including medial “buttress” fully threaded cortical screws and lateral “shoulder” screws

Anterior Screw Fixation:

• This example:

• 4.0 mm partially threaded compression screws through non-comminuted columns

• Mini-fragment (2.4 mm) screws for osteochondral fragments

• Consider Titanium for MRI

Plate Fixation:

• Very useful in comminuted fractures:• 2.0 or 2.4 mm plates

• Easiest to apply to lateral cortex – impinge on medial side


Hawkins 3

Complications

• AVN

• Malunion

• Nonunion

• Arthritis


Results

• Chateau, Indy, 2002 JOT

• 23 pts, 20 mo F/U

• Dual, mini fragment

• “Low” rate AVN

• Elgafy, Foot Ankle 2000• 60 fx• Arthritis:

• Ankle 25%, Subtalar 53%

• AVN 16%

• Harborview, 2002 OTA• 60 fx, 30 mo F/U

• w/in 24 hr (40 pts)/• Dual 91%• Worse results with:

• Comminution• Open

• Osteonecrosis• 39% (II) 56% to

collapse• 64% (III) 67% to

collapse

AVN: Incidence after Talus Fracture

• Canale (1972): • I: 15 %

• II: 50 %

• III: 85 %

• IV: 100 %

• Behrens (1988):• Overall 25 %

• Ebraheim/Stephen(2001):• Overall 20 %


AVASCULAR NECROSIS

• Rates with Hawkins Class

• AVN does not = poor result

• ? MRI-probably not prognostic

• ? Does early ORIF minimize AVN

AVN: Diagnosis

• Hawkins’ Sign: Xray finding 6-8 weeks post injury

• Presence of subchondral lucency implies revascularization

AVN: Imaging

• Plain radiographs: sclerosis common, decreases with revascularization

• MRI: very sensitive to decreased vascularity


Hawkins 3


1 year follow-up

|Osteonecrosis without collapse

Bilateral Injuries Fixed at 72 hours

2 years – Pain, Stiffness, Limp

Hawkins III Hawkins II

AVN Treatment:

• Precollapse:• Modified WB

• PTB cast

• Compliance difficult

• Efficacy unknown

• Postcollapse:• Observation

• “Blair fusion” is one option if symptomatic

Malunion: Incidence

• Common: up to 40%

• Most often Varus

Malunion: Diagnosis

• Varus hindfoot, midfoot supination on clinical exam

• Dorsal malunion on Xray

Malunion

• Mechanical effects• > 3 degrees malunion:

decreased subtalar ROM

(Daniels TR, JBJS 1996)

• > 2mm: altered subtalar contact forces (Sangeorzan

J Orthop Res 1992)

Clinical Effect of Malunion

• Malunion:• More pain

• Less satisfaction

• Less ankle motion

• Worse functional outcome

Malunion Rx:• Talus osteotomy

• Calcaneus osteotomy

• Possible midfoot osteotomy

• Tendo Achilles Lengthening


Arthrosis (Subtalar)

• Pain &/or stiffness – 16 (52%)• Dx arthrosis – 6 (19%)• Subtalar arthrodesis – 3 (10%)

Post Traumatic Arthritis

• Incidence of post-traumatic arthritis

• 30-90 %

Post-Traumatic Arthritis

• Most commonly involves Subtalar joint

• Rx: Arthrodesis

Nonunion

• Uncommon, even with AVN

• Delayed Union very common

• Frequently results in late malalignment

Talar Body Fractures

• Treatment strategy and outcomes similar to talar neck fractures

• Medial or Lateral Malleolar Osteotomy frequently required

Medial Malleolar Osteotomy

• Predrill and pretap malleolus

• Osteotomy aims just off the medial corner of mortise to facilitate interdigitation

• Chevron, straight, or stepcut techniques

• Osteotome to crack cartilage helps avoid mortise malalignment

Talar Body + Fibula Fracture

• Visualize body through the fibula fracture

Talar Body Case Example

• 58 year old female

• 4 week old fracture

• Missed initially

Case, cont’d

• Extensive comminution into subtalar joint

• Poor bone quality

Selected Rx: Primary Arthrodesis

Tricortical bone graft to reconstitute talar height

Osteochondral Injuries

• Frequently encountered with talus neck and body fractures

• Require small implants for fixation

• Excise if unstable and too small to fix

Osteochondral Injuries

Osteochondral Fragment Repair

Large fragment repaired, small fragment excised

Talar Head and Process Fractures

• Treat according to injury

• Operate when associated with joint subluxation, incongruity, impingement or marked displacement

• Fragments often too small to fix and require excision

Case Example: Talar Head Fracture

• Talar head injury

• Subtle on plain x-ray

Talar Head Fracture, continued

• CT demonstrates subtalar injury and subluxation

Treatment of Talar Head Fracture

• Required 2 incisions to debride subtalar joint from lateral approach, and reduce / stabilize fracture from medial side

Lateral Process Example• Usually require CT scan

• Often excised due to size of fragments

• Difficult to achieve union

Lateral Talar Process Fractures

• “Snowboarder’s fracture”• Mechanism: may occur from inversion (avulsion

injury) or eversion and axial loading (impaction fracture)

• Often misdiagnosed as “ankle sprain”• Best results if treated early, either by

immobilization, ORIF or fragment excision• If diagnosed late consider fragment excision as

attempts to achieve union often fail

Talus Fracture AO/ASIF Classification

Lateral Process (81-A2.1)

Treatment Options

• Non-operatively for minimally displaced fractures

• Excision of fragment

• Isolated mini fragment screws

• Mini plate fixation

Fracture Complications

• Extend into subtalar joint

• Accelerated post-traumatic arthritis pain stiffness disability subsequent surgery for subtalar

joint fusion

Mini Plate Procedure1. Lateral approach2. Subtalar chondral debris

removed3. Impaction elevated if

present & filled with allograft if required

4. Preliminary 0.45 Kirschner wire (K-wire) fixation.

5. 2.0 mm “T” plate applied upside down

6. Lag screw fixation - avoiding overcompression with comminution

Talar FractureIsolated Lateral Process

Talus FractureLateral Process & Talar Neck

Marginal ImpactionComminuted Fracture

Posterior Talar Process Fracture

• 2 components: medial and lateral tubercle

• Groove for FHL tendon separates the two tubercles

• Differentiate fracture from os trigonum – well corticated, smooth oval or round structure

Posterior Talar Process Fractures

• Medial tubercle fracture: “Cedell’s fracture”

• Lateral tubercle: “Shepherd’s fracture”

• Treatment: immobilize or excise or ORIF

Treatment

• Usually associated with Talar Neck Fx

• Posteromedial Approach behind Neurovascular Bundle

• Medial Malleolar Osteotomy – usually not effective for exposure or fixation

Example – 18 yo “Car Surfer”

CT Evaluation

Treatment – 3 Incisions

Subtalar Dislocations

• Spectrum of injuries

Relatively Innocent

Very Disabling

Classification

• Usually based upon direction of dislocation:

• Medial dislocation: 85 %, low energy

• Lateral dislocation: 15 %, high energy

Other Important Considerations:

• Open vs Closed

• High or low energy mechanism

• Stable or unstable post reduction

• Reducible by closed means or requiring open reduction

• Associated impaction injuries

All have prognostic significance:

Important Distinction:

• Total talar dislocation, or pan talar dislocation

• Results from continuation of force causing subtalar dislocation

• High risk of AVN, usually open, poor prognosis

Open pantalar dislocation with skin loss showing Incongruent reduction: Result was AVN and

pantalar fusion

Management of Subtalar Dislocation

• Urgent Closed reduction:• Adequate sedation

• Knee flexion

• Longitudinal foot traction

• Accentuate, then reverse deformity

• Successful in up to 90 % of patients

Open Reduction:

• More likely after high energy injury

• More likely with lateral dislocation

• Cause:• soft tissue interposition

(Tib post, FHL, extensor tendons, capsule)

• bony impaction between the talus and navicular

Rehabilitation:

• Stable injuries: • 4 weeks immobilization

• Physio for mobilization

• Unstable injuries:• Usually don’t require internal fixation once reduction

achieved

• If necessary – external fixation or transarticular wire fixation

Outcome of Subtalar Dislocations:

• Less benign than previously thought

• Subtalar arthritis:• Up to 89 % radiographically

• Symptomatic in up to 63 %

• Ankle and midfoot arthritis less common

Summary:

Talar Neck Fractures• Anatomy• Incidence• Imaging• Classification• Management• Complications

Talar body, head and process fractures

Subtalar dislocations• Classification• Management • Outcomes

Selected References

Hawkins LG 1970 Fractures of the neck of the talus. J Bone Joint Surg Am 52(5):991-1002.

Canale ST, Kelly FB, Jr. 1978 Fractures of the neck of the talus. Long-term evaluation of seventy-one cases. J Bone Joint Surg Am 60(2):143-56.

•the two classics on talus fractures. Rates of AVN, classification, etc. Good descriptive papers.

Additional Clinical papers:

Elgafy H, Ebraheim NA, Tile M, Stephen D, Kase J 2000 Fractures of the talus: experience of two level 1 trauma centers. Foot Ankle Int 21(12):1023-9.

Metzger MJ, Levin JS, Clancy JT 1999 Talar neck fractures and rates of avascular necrosis. J Foot Ankle Surg 38(2):154-62.

Pajenda G, Vecsei V, Reddy B, Heinz T 2000 Treatment of talar neck fractures: clinical results of 50 patients. J Foot Ankle Surg 39(6):365-75.

Selected ReferencesRecent Literature:

Sanders DW, Busam M, Hattwick E, Edwards JR, McAndrew MP, Johnson KD. Functional outcomes following displaced talar neck fractures. J Orthop Trauma 2004; 18: 265-270.

Vallier HA, Nork SE, Barei DP, Benirschke SK, Sangeorzan BJ. Talar neck fractures: results and outcomes. J Bone Joint Surg 2004; 86-A: 1616-1624.

-Good outcome papers on talar neck

Fleuriau Chateau PB, Brokaw DS, Jelen BA, Scheid DK, Weber TG. Plate fixation of talar neck fractures: preliminary review of a new technique in twenty-three patients. J Orthop Trauma. 2002;16(4):213-9.

-plate fixation discussed

Vallier HA, Nork SE, et al. Surgical treatment of talar body fractures. J Bone Joint Surg 2004; Supp 1: 180-92; and 2003; 85-A: 1716-24

- good talar body review and surgical technique

Bibbo C, Anderson R, Marsh WH. Injury characteristics and the clinical outcome of subtalar dislocations: a clinical and radiographic analysis of 25 cases. Foot ankle int 2003: 24: 158-63.

-best current info on subtalar dislocations

References Cont.

Biomechanics

Sangeorzan BJ, Wagner UA, et al. Contact characteristics of the subtalar joint: the effect of talar neck misalignment. J Orthop Res 1992; 10(4): 544-51.

Daniels TR, Smith JW, Ross TI. Varus malalignment of the talar neck. Its effect on the position of the foot and on subtalar motion. J Bone Joint Surg Am. 1996; 78: 1559-67.

Swanson TV, Bray TJ, Holmes GB Jr. Fractures of the talar neck. A mechanical study of fixation. J Bone Joint Surg Am 1992; 74(4): 544-51.

Attiah M, Sanders DW et al. Comminuted talar neck fractures: a mechanical study of fixation techniques. J Ortho Trauma 2007; 21: 47-51.

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Fractures of the Talus and Subtalar Dislocations

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