Talar Neck Complications

AVN  

 

Largely related to degree of displacement

 

Incidence

 

Hawkins Type I

- 0% to 13% 

 

 

Hawkins Type II 

- 20% to 50% 

- usually only patchy and not a problem (rarely collapses)

- usually unites 

 

Hawkins Type III / IV

- 90% to 100% 

- often a problem

 

 

 

 

Hawkins Sign 1970

 

Means talus is vascularised

- makes diagnosis of AVN unlikely

 

AP view

- at 6 - 8 weeks see disuse atrophy of bones

- due to NWB

- thin rim of radiolucency under cartilage of talar dome

- subchondral atrophy

 

MRI 

 

Best method to diagnose AVN

 

 

CT

 

 

NHx

 

Usually posterolateral corner

- furtherest from medial blood supply

 

Collapse occurrs despite years of NWB

- NWB does not prevent collapse 

 

Creeping substitution can take up to 36 months

Collapse in most is well tolerated

Hawkins advocates weightbearing once united as re-ossification takes years

 

Management Limited collapse with OA

 

Arthrodesis of the affected joint

 

Management Complete collapse

 

Issue

- have a dead talus

- very difficult to obtain tibio-talar-calcaneal fusion

 

1.  Blair fusion / tibio-talar arthrodesis / sliding anterior tibial graft

 

 

Advantage

- maintains length

 

Anterior approach between EDL and EHL

- excise avascular body

- use saw to take 5 x 2.5 cm graft anterior tibia

- slide graft from distal tibia

- insert into notch in residual viable talar neck and head

- foot in 0^o DF, 5^o valgus, 10^o ER

- single screw x graft into tibia

- additional tibio-talar scrws

- Pack cancellous bone grafts around the fusion site.

- Apply a long leg cast with the knee flexed 30^o

 

Results

- 4 united, 3 pseudos

- 5 good, 1 fair, 1 poor

 

2.  Pantalar fusion with IM nail

 

3.  Ilizarov Tibio-calcaneal Fusion 

 

Disadvantage talus excision

- makes leg short

- 3cm short on average

 

Technique

- frame tibio-calcaneal fusion

- Ilizarov proximal corticotomy and lengthening

 

Mal-union 

 

Incidence

 

More of a problem than AVN in Type II 

- may be up to 40%

- most common with non operative or single incision operations

 

Issue

 

Varus secondary to medial comminution

- creates cavus foot with supination

- walk on lateral border of foot / walk with IR foot

- predispose to premature OA

 

Options

 

1.  Talus osteotomy

2.  Medial column lengthening with tri-cortical graft

3.  Lateral column shortening

 

Arthritis

 

Subtalar joint arthritis

- most common complication

- rarely requires fusion

 

Non operative

 

STJ 

- UCBL

 

Ankle 

- moulded AFO

 

Operative

 

Fusion

 

Delayed Union 

 

Definition

- > 6 months

- incidence is 10%

- very common

 

Non-union

 

Definition

- >12 months

- rare