An approach to ankle x-rays

Aric Storck PGY2(acknowledgement to Dr. Dave Dyck for several slides)

September 11, 2003

Objectives

Review basic ankle fracture classification

Review x-rays of common ankle fractures

Discuss management of common ankle fractures

Case 1:

25 year old female• Jumped off roof

• Right ankle pain

• Inability to weight bear on right foot

What else do you want to know on history and physical examination?

Does she need x-rays ?

Ottawa Ankle Rules:

Order ankle x-rays if acute trauma to ankle and one or more of• Age 55 or older

• Inability to weight bear both immediately and in ER (4 steps)

• Bony tenderness over posterior distal 6 cm of lateral or medial malleoli

Sensitivity ~100% Specificity ~40%

You have decided to order an “ankle x-ray.” The nurse entering your orders asks which views you want …

Ankle X-rays: 3 views

AP• Identifies fractures of malleoli, distal tibia/fibula,

plafond, talar dome, body and lateral process of talus, calcaneous

Mortise• Ankle 15-25 degrees internal rotation

• Evaluate articular surface between talar dome and mortise

Lateral • Identifies fractures of anterior/posterior tibial margins,

talar neck, displacement of talus

AP x-ray:

Identifies fractures of • malleoli

• distal tibia/fibula

• plafond

• talar dome

• body and lateral process of talus

• calcaneous

Tib/fib clear space Tib/fib overlap

AP xray

Now apply what you’ve learned …

Lateral malleolar fracture

Tib/fib clear space <5mm

Tib/fib overlap >10 mm

No evidence of syndesmotic injury

Mortise X-Ray

Taken with ankle in 15-25 degrees of internal rotation

Useful in evaluation of articular surface between talar dome and mortise

Mortise x-ray:

Medial clear space• Between lateral border of

medial malleous and medial talus

• <4mm is normal

• >4mm suggests lateral shift of talus

Mortise x-ray:

Talar tilt • Normal = -1.5 to +1.5

degrees (ie. Parallel)

• Can go up to 5 degrees in stress views

• <2mm difference between medial and lateral talar/plafond distances

Lateral x-ray:

Identifies fractures of • Anterior/posterior tibial

margins

• Talus

• Displacement of talus

• Os trigonum

Stable vs Unstable

The ankle is a ring• Tibial plafond

• Medial malleolus

• Deltoid ligaments

• calcaneous

• Lateral collateral ligaments

• Lateral malleolus

• Syndesmosis Fracture of single part usually

stable Fracture > 1 part = unstable

Source: Rosen

Walking the walk ….Talking the talk

Ortho is on the phone. They ask you to describe the fracture….

Lauge-Hansen:

15 basic types of injury in 5 major categories• Described by two words

1.Position of foot at time of injury

2.Direction of talus within mortise causing fracture

• Eg: supination-external rotation

• Further subdivided into worsening areas of injury

Impossible to remember and clinically useless in the ED

Danis-Weber

• Defines injury based on level of fibular fracture• A=below tibiotalar joint

• No disruption of syndesmosis

• Usually stable

• B=at level of tibiotalar joint

• Partial disruption of syndesmosis

• C=above tibiotalar joint

• Disrupts syndesmosis to level of fracture

• unstable

• THE MORE PROXIMAL THE FIBULAR # THE MORE SEVERE THE INJURY

AO classification:

Similar to Danis-Weber scheme

Takes into account damage to other structures (usually medial malleolous)

~2 pages of classifications• Remember them all for your exam!

AO classification

Pott’s classification:

Easy to remember

First degree• unimalleolar

Second degree• bimalleolar

Third degree• trimalleolar

Case 2

Lateral Malleolar FractureDanis-Weber A

Mechanism• Suppination/adduction (inversion)

Mortise intact Stable fracture Treatment

• Below knee cast

Case 3

Bimalleolar (lat & post malleoli)

Mechanism• Inversion

• Avulsion of posterior malleolus (post tibiofibular ligament)

Medial mortise wide• Suggests instability

Management• Posterior slab

• Orthopedic consult

Source: McRae’s Practical Fracture Treatment

Case 4

Unstable• Multiple ligamentous injuries

• Usually involves syndesmosis

Treatment• Posterior slab

• Urgent orthopedic consultation

• ORIF

Trimalleolar Fractures

Source:Rosen

CASE 5

Fracture of distal tibial metaphysis• Often comminuted

• Often significant other injuries Mechanism

• Axial load

• Position of foot determines injury Treatment

• Unstable

• X-ray tib/fib & ankle

• Orthopedic consultation

Pilon (tibial plafond) fractures

Source:Rosen

Case 6

Tillaux Fracture

Occurs in 12-14 year olds• 18 month period when epiphysis is closing

Salter-Harris 3 injury• Runs through anterolateral physis until reaches fused part,

then extends inferiorly through epiphysis into joint

• Visible if x-ray parallel to plane of fracture (may require oblique)

Mechanism• External rotation

• Strenth of tibiofibular ligament > unfused epiphysis

Tillaux Fracture

Management• Inadequate reduction of articular surface can lead

to early OA

• Gap >2mm in articular surface is unacceptable

• Advanced imaging techniques may be necessary

• Early orthopedic consultation

• Non-displaced• NWB below knee cast

• Displaced• surgery

Case 7

Source: Rosen

Maisonneuve Fracture

Mechanism• Eversion + lateral rotation

• May cause medial malleolar fracture or deltoid ligament disruption

• Injury proceeds along syndesmosis and involves proximal fibula

Always rule out Maisonneuve fracture in medial malleolar/ligamentous injury

Maisonneuve Fracture

Mechanism• Eversion + lateral rotation

• Causes medial malleolar fracture or deltoid ligament disruption

If injury proceeds along syndesmosis it involves proximal fibula = Maisonneuve Fracture

Always rule out Maisonneuve fracture in medial malleolar/ligamentous injury

As talus continues to rotate• Posterior tib-fib ligament ruptures

• Interosseous membrane rips

• Gross diastasis

• Dupuytren fracture – dislocation of the ankle

Case 8

the end