Trauma Skeletal Radiology

ANKLE

Leese Brimicombe Clinical Specialist Skeletal Radiology Systematic Film Evaluation

 Alignment   Cartilage  Soft Tissue

Alignment

 Bowing  Normal position of bones  Spaces between bones  Symmetry  Angulations Bones

 Periosteal Reaction  Anomalies in the cortex, breaks, overlaps & steps.  Changes in trabecular pattern  Changes in densities Cartilage

 Avulsion fractures  Misalignment  Effusions  Calcification

Soft Tissue

 Defect on normal contours

 Obvious swelling

 Foreign body (e.g. glass) in soft tissues

 A fluid/solid interface (lipohaemoarthrosis)

 A gas/fluid interface (perforation)

Suspected trauma P P

Indicate the following on the request form: R Side involved and body part R Mechanism of injury Exact site of focal tenderness related to a specific or (IRMER requirement) O Incomplete/Inadequate requests O without all the above information may not be processed. T T O O If clinical findings remain unexplained recheck that imaging for the area of clinical concern has been requested with the C relevant and appropriate clinical C Information O O

Appropriate further management ? Need for delayed imaging/fracture clinic L referral L

CRS Requests for Trauma

Must include:  Side involved and body part  Mechanism of injury and timescale  Exact site of focal tenderness related to a specific bone  Relevant clinical history  Important supplementary information – such as patient has CA

Anatomy

AP MORTICE Anatomy Ligaments in the ankle

ATFL = Ant. Tibiafibular Ligament

ATFL = Ant. Talofibular Ligament

PTFL = Post. Talofibular Ligament

CFL = Calcanofibular Ligament

Peroneus Brevis Re-attachment of PB Good Ankle Views

AP Mortice View Lateral Ottawa Ankle Rules

• Pain in the malleolar zone + any one of the following:

• Bone tenderness along the distal 6 cm of the posterior edge of the or tip of the lateral malleolus.

• Bone tenderness along the distal 6 cm of the posterior edge of the or tip of the medial malleolus.

• Inability to bear weight for 4 steps both immediately and in the emergency department. STABILITY

• Rings of stability are seen in both the coronal and axial planes. • Problems occur when there is a combination of a fracture and a ligament rupture • Ligament ruptures are not seen on x-ray. • Some proximal fibular fractures are also not visible on the ankle x-rays, when in combination with ligamentous rupture at the same level. • Thus x-rays may look normal when there is an unstable ankle injury. STABILITY

• For ankle stability it doesn't matter whether it is a rupture of a ligament or an avulsion at the insertion. • Almost every ligamentous rupture has a fracture equivalent. STABILITY – lateral joint space

 The lateral joint space is measured from the medial border of the fibula to the lateral border of the posterior tibia.  It is less well defined because its width varies with positioning.  Evident diastasis of the lateral joint space indicates syndesmosis rupture.  A width of 5.5 mm is probably abnormal.  A normal lateral or medial joint space does not exclude ligamentous rupture.  It simply means that there is no dislocation,  Instability cannot be excluded.

STABILITY – medial joint space

 Should not exceed 4 mm  Usually equal to the distance between the tibial plafond and the talus.  Widening of the medial joint space up to 6 mm or more requires disruption of the medial collateral ligament. ZONE OF VULNERABILITY Adduction/Inversion Inversion & External Rot. ZONE OF VULNERABILITY Eversion ZONE OF VULNERABILITY Forced Dorsiflexion Types of Injury

The shape of a fracture indicates which forces were involved.

• PUSH OFF INJURY • An oblique or vertically oriented fracture

• PULL OFF INJURY • A transverse or horizontal fracture

Weber Classification

Weber A Weber B Weber C Weber A Stage 1 (20-25%)

 Results from an adduction force on the supinated .  The lateral aspect is under extreme tension and the ligaments stretch  This can cause an  Almost always the avulsion is seen as a horizontal fracture  A “ pull off “ type of fracture. Weber A Stage 2 - Uncommon

 More adduction force results in the medial malleolus being pushed off in a vertical or oblique fracture.

 Stage 2 is unstable because the ring of the ankle is broken in two places

 A horizontal fracture of the lateral malleolus and the vertical fracture of the medial malleolus.

Weber B – Common 60%

 Stage 1 is usually not visible on x-rays, as it is a anterior tibio-fibular ligament rupture.  Stage 2 is commonly seen as a result more rotation of the talus, causing a fracture of the fibula in an oblique or spiral fashion, through the syndesmosis  It is probable that there is also a rupture of the ATFL, which is stage 1.

Weber B

Stage 3  More posterior displacement of the lateral malleolus fragment by the talus results in tension on the posterior syndesmosis  With rupture or avulsion fracture of the tertius (at the peroneus tertius attachment).

Weber B

Stage 4  Further posterior movement of the talus resulting in extreme tension of the medial aspect  The deltoid ligament will either rupture or pull off the medial malleolus

What stage? Small linear density on the AP-view = PTM or Tertius fracture Soft tissue swelling on the medial side is probably a rupture of the medial collateral band. Weber C Sequence

1. Medial avulsion fracture or rupture of the collateral band 2. Rupture of the anterior syndesmosis 3. Supra-syndesmotic rupture of the fibula due to rotation 4. Malleolus tertius fracture or rupture of the posterior syndesmosis

Weber C – 20%

Stage 1 • Will occur on the medial side, which is under maximum tension due to the pronation. • Leading to rupture of the medial collateral ligament or avulsion of the medial malleolus. • The injury can stop there with only a rupture of the medial collateral ligaments or avulsion of the medial malleolus. • In many cases the injury progresses to a higher stage. Ankle – Weber C

Stage 2 • The talus rotates externally Stage 3 and moves laterally as it is • Continuous force twists the free from its medial fibula and displaces it attachment. distally, while proximally it • Due to pronation, the lateral is fixed to the tibia. ligaments are not under • Finally the interosseous tension and fibula can move membrane will rupture up to away from the tibia, causing the point where the fibular a rupture of the anterior shaft fractures such as a syndesmosis. maisonneuve injury Weber C – Stage 3 Weber C

 Stage 4 - Avulsion of the malleolus tertius or - rupture of the posterior syndesmosis

Weber C – Stage 4 Gravity Stress View

Used to predict the need for surgical fixation of Weber Fractures

Test for medial instability in lateral malleolus fractures without any talar shift, as there is uncertainty regarding involvement of the deltoid ligament. Deltoid ligament injuries with a fractured lateral malleolus are more likely to require surgical intervention due to instability. Deltoid Ligament Medial Malleolus Bi Malleolus Tri maleolus Fracture

 An avulsion of anterior lateral margin of the distal tibia  It is caused by a twisting injury  Anterior tibio-fibular ligament avulses a small portion of the tibia.

Pilon Fracture

• Fracture of distal tibia at the articular surface with the talus

• Occurs when talus hits the tibia bone with an direct upward force Triplane Fracture

 Also known as Marmor-Lynn fracture  Typically occurs in adolescents  Twisting Injury  Term refers to 3 fractures of the tibia: – vertical fracture through the epiphysis – horizontal fracture through the physis – oblique fracture through the metaphysis

1. Vertical # through the epiphysis 2. Horizontal # through the physis Triplane # 3. Oblique # through the metaphysis

Maisonneuve Fracture Toddlers Fracture Accessory Ossicles

Os Tibule Os Sub Tibulare Externum Accessory Ossicles

Os trigonum Supranaviculare Os Sub Fibulare Pitfalls - Ankle

Internal rotation of foot causing calcanium to overlie the lateral mallelous Not showing the base of 5th metatarsal Over rotation on lateral view Not true mortise view Not flexing the foot so the talar dome isn’t seen clearly Cutting off soft tissue or over penetrating it – soft tissue swelling is significant in ankle injuries. Questions?