Talar Neck Fracture

Epidemiology

 

Second most common  hindfoot after calcaneal fractures

 

Aetiology

 

Aviators Astragalus

 

Fall from height

- hyper-dorsiflexion injury

- neck of talus strikes the anterior tibia

 

Anatomy

 

More than half surface covered by articular cartilage

- medial articular wall straight

- lateral articular wall curves posteriorly

- meet at posterior tubercle

 

Neck of talus

- medially 10 - 44o from axis of body

- plantar 5 - 50o

 

No muscle or tendon attachments

 

Ligaments

- deep deltoid medially

- ATFL, PTFL

- FHL tendon in groove posteriorly

- head supported by spring ligament (CN ligament)

 

Facets

- posterior / middle / anterior

- correspond to calcaneal facets

- sinus tarsi between posterior and middle

 

Blood Supply

 

3/5 talus covered by articular cartilage

- blood can only enter through 2/5

 

1.  Posterior tibial / artery of tarsal canal

- main supply to body

- branches to deltoid ligament

- enters talar neck and supplies most of body

 

2.  Anterior tibial / Dorsalis pedis

- supplies head and neck

 

3.  Peroneal / artery of tarsal sinus

- supplies head and neck head and neck

 

Pathology

 

Often with rotation 

- with DF body of talus locks in mortice 

- fracture neck on tibia

- remainder of foot displaces medially thru STJ 

- disrupt inter-osseous and lateral / posterior ligaments 

- dislocation of STJ and AKJ 

 

Body of talus is forced out postero-medially swinging on intact deltoid

- comes to lie posterior to medial malleolus & anterior to T achilles

- often associated medial +/- lateral malleolus fracture

 

Classification Hawkins 1970

 

1.  Undisplaced fracture

 

Talar neck 1

 

Fracture of neck between posterior and medial facet

- precluded by any displacement of 1 - 2 mm

- may need CT to confirm

- means only one blood supply is disrupted

 

AVN 10%

 

2.  Subluxation / dislocation STJ

 

Subluxed posteriorly or medially

- blood supply through neck and in canal disrupted

- blood supply through medial body usually maintained

 

AVN 39% Vallier et al JBJS Am 2004

 

Talar Neck Fracture

 

3.  Subluxed STJ &  AKJ 

 

Body extruded postero-medially

- head maintains relationship with navicular

- 25 % open 

- all three blood supplies are disrupted

 

Talus Fracture Type 3

 

AVN 67% Vallier et al JBJS Am 2004

 

4.  Type 3 + subluxed TNJ

 

Dislocation of head and neck

- poor outcome

- significance is that blood supply to head may also be disrupted

 

AVN 90 - 100%

 

Hawkins 4 Talar Neck FractureHawkins 4 Talar Neck Fracture AP

 

Examination

 

Open wounds

 

Compound Talus

 

Skin under threat (Type III / IV)

 

NV compromise

- fragment can compress circulation

 

X-ray

 

Canale view

- evaluates talar neck

- foot 15o pronated

- beam angled 75o to foot

- look for medial shortening / varus

 

CT

 

Management

 

Non-operative

 

Indication

 

Only for true type 1 injuries

 

Technique

 

Frequent review to prevent loss of position

SL NWB POP 6/52

 

Operative Management

 

Goal

 

Anatomic reduction

- rotation / length / angulation of talar neck

 

Any displacement of 2mm

- increases contact stresses of STJ

- leads to premature STJ OA

 

Closed Reduction

 

Occasionally need to do closed reduction

- pressure on skin

- vascular compromise

- patient severely injury

 

Technique

- flex knee to relax gastrocnemius

- traction on plantarflexed foot to realign head and body

- varus / valgus correct as required

- place temporary percutaneous K wires

 

Timing of Surgery

 

Does early reduction prevent AVN?

 

Vallier et al JBJS Am 2004

- 102 patients

- no evidence that surgical delay increased AVN

- AVN associated with neck comminution and open fractures

- recommend is reasonable to wait for swelling to subside

 

Sanders 2004 JBJS Am

- similar conclusion

- 29 patients

- delay in surgery did not affect union or AVN rates

 

Surgical Technique

 

1.  Closed Type 2 - 4

 

Position

- supine on radiolucent table

- tourniquet, IV Abx, II available

 

Incisions

- 2 incision technique

 

Anteromedial 

- just medial to T anterior tendon 

- begin at TNJ

- can extend to MM

- no stripping of dorsal neck

- preserve deep deltoid for blood supply

- may require medial malleolar osteotomy

- in this case can curve incision up and around medial malleolus

 

Anterolateral

- allows assessment of reduction

- lateral screw prevents compression into varus and loss of medial length

- lateral to EDL, mobilise EDB

- > 7 cm skin bridge

- expose lateral talar neck

 

Reduce and ORIF

- only accept anatomical reduction

- avoid varus and shortening medial neck

- anteromedial and anterolateral K wires

- insert proximal to articular surface of head

- aim into posterior body

- parallel

- check II

- cannulated lag screws (titanium for future MRI)

- minifragment screws for osteochondral fragments

 

Talus ORIF APTalus ORIF LateralTalus ORIF

 

2.  Devitalised Type 3 / 4 with compound wound

 

Managment is controversial

 

1.  Reasonable to clean / replace / ORIF

- if become's infected remove 

- Abx spacer

- apply frame

- fuse late once infection cleared +/- lengthening

 

Compound Talus ORIF 1Compound Talus ORIF 2Compound Talus ORIF

 

Talus ORIF APTalus ORIF Lateral

 

2.  Can discard primarily & close wound

- fusion once soft tissues healed

- acute shortening and fusion with frame with proximal corticotomy and lengthening