Part 5: Fractures

 

Plain radiographs are the mainstay of trauma imaging.

At least two radiographic views at 90˚ to each other must be taken of any suspected injury.

Ideally 3 views for foot trauma - AP, oblique and lateral. Weight-bearing comparison views can be helpful.

 

Salter-Harris fracture

Involves the physis of an immature skeleton.

Classification can be remembered using the mnemonic SALTR:

  1. Slip of the physis
  2. Above the physis
  3. Lower than the physis
  4. Through the physis
  5. Rammed physis

 

Tillaux fracture

Salter-Harris type 3 fracture through the anterolateral distal tibial epiphysis.

Variable displacement. Occurs in older children and adolescents when the medial distal tibial growth plate has started to fuse.

 

Triplanar fracture

Salter-Harris type 4 fracture through the lateral distal tibia with sagittal, axial and coronal plane components.

Comprises a vertical fracture through the epiphysis, horizontal fracture through the physis and oblique fracture through the metaphysis.

Triplanar fracture extending through the distal tibial epiphysis, physis and metaphysis (arrows)

 

Danis-Weber ankle fracture classification

For description of lateral malleolar (distal fibula) fractures

Relates to the level of the fracture in relation to the ankle joint

Weber A

Below level of the talar dome

Usually transverse (pull-off)

Tibiofibular syndesmosis intact

Deltoid ligament intact

Medial malleolus occasionally fractured (push-off)

Usually stable if medial malleolus intact

 

Weber B

At level of the talar dome; may extend proximally

Usually spiral

Syndesmosis usually intact, but widening of the distal tibiofibular joint indicates syndesmotic injury

Medial malleolus may be fractured or

Deltoid ligament may be torn

Variable stability; depends on status of medial structures and syndesmosis

Sub-classification:

B1: isolated

B2: associated with a medial lesion (# or ligament)

B3: associated with a medial lesion and posterolateral tibial fracture

 

Weber Type C

Above level of the syndesmosis

Syndesmosis disruption with widening of distal tibiofibular articulation

Medial malleolar fracture or deltoid ligament injury

Fracture may arise as proximally as the fibular neck

NB: If a medial malleolar fracture and/or widening of the mortise joint is noted, proximal radiographs should be performed to rule out a proximal fibular (Maisonneuve) fracture.

 

Pilon fracture

Distal tibial fracture with intra- articular extension

Usually compression (axial-loading) injury

Often fall from height

Check for other injuries: talar, calcaneal or spinal fracture

 

Talar neck fracture

Impaction of talus on tibia during forced ankle dorsiflexion

May lead to disrupted blood supply to the talar body with subsequent avascular necrosis

The ‘Hawkins’ sign describes subchondral lucency of the talar dome 6-8 weeks after a talar neck fracture; indicates sufficient vascularity in the talus

Absence of the Hawkins sign, seen as subchondral sclerosis may indicate disruption to the blood supply of the talar dome and underlying AVN

Hawkin’s sign with subchondral lucency of the talar dome (arrows)

 

Calcaneal fracture

Common following a fall from height

Extra-articular: 25-30%

Anterior calcaneal process fracture, calcaneal tuberosity avulsion, extra-articular body fracture, sustentaculum

Intra-articular: 70 – 75%

Usually comminuted

‘Double density’ sign due to impacted fracture, subtalar incongruity and separation of sustentaculum

Decreased Bohler’s angle <20°

Increased Gissane angle >145°

Shear fracture in sagittal plane splits calcaneus into anteromedial (sustentacular) and posterolateral (tuberosity) fragments.

Compression fracture in coronal plane with anterior limb running through critical angle of Gissane and posterior limb extending either horizontally in axial plane toward the tuberosity in tongue type fracture or more vertically, behind the posterior facet in joint depression type fracture.

Look for lateral malleolar ‘fleck’ sign which raises likelihood of peroneal tendon instability.

Calcaneal fracture: tongue type                                Calcaneal fracture: joint depression type

 

Chopart fracture

Fracture-dislocation through the midtarsal joint (calcaneocuboid and talonavicular).

 

Lisfranc fracture

Fracture-dislocation of the tarsometatarsal joints.

Key to normal alignment is that the medial border of the second metatarsal should always line up with the medial border of the intermediate cuneiform on the AP view and the medial margin of the third metatarsal should line up with the medial margin of the lateral cuneiform on the oblique view.

May be missed if subluxation is minimal.

Gap > 2mm between bases of 1st and 2nd metatarsals.

‘Fleck sign’ indicates small avulsion fragment, from lateral edge medial cuneiform or medial 2nd

metatarsal base.

Lisfranc fracture with widening between 1st and 2nd MT bases, malalignment of the 2nd metatarsal (2MT) and intermediate cuneiform (IC). Fleck sign (arrow) indicating small avulsion from 2nd MT base

 

Fifth metatarsal base fractures

Avulsion fracture of the base of the fifth metatarsal

Caused by pull off peroneus brevis tendon.

Differentiate from normal unfused apophysis; fracture line lies transverse to the long axis of the metatarsal whereas an apophysis lies parallel to the long axis of the metatarsal.

Avulsion fracture base 5th metatarsal and normal apophysis

 

Jones fracture

Extra-articular transverse fracture at the metadiaphyseal junction of the fifth metatarsal.

Higher chance of non-union due to watershed vascularity.

 

Stress fracture

Occurs as a result of repetitive stresses or overload on bone.

Recognised sites include:

tibia and fibula in long distance runners;

calcaneum and metatarsals secondary to walking (“March fracture”) and prolonged standing.

Seen as a linear band of sclerosis with periostitis.

3rd metatarsal stress fracture with periostitis (arrowheads)