Fracture: Ankle

Radiographic findings may include:

  • a linear or curvilinear decreased density dividing a bone into two or more segments
  • ill-defined increased density

Here are presentations of ankle fractures (with *interpretations):

  • Case 1
  • *Case 1
  • Case 2
  • *Case 2
  • Case 3
  • *Case 3
  • Case 4
  • *Case 4
  • Case 5a
  • *Case 5a
  • Case 5b
  • *Case 5b
  • Case 6
  • *Case 6
  • Case 7
  • *Case 7
tibia avulsion fracture
tibia avulsion fracture marked

Anteroposterior ankle view.
The medial malleolus anterior collioculus (a) is separated from the posterior colliculus.
Diagnosis: avulsion fracture tibial mallelous.

avulsion fracture fibula
a fibula avulsion fracture b fibula avulsion fracture 2

Anteroposterior (a) and medial oblique (b) ankle views.
a) Initial radiographs demonstrated multiple, irregular ossicles inferior to the tip of the malleolus.
b) Several months later the fragments coalesced into one ossicle, which is more defined.
Diagnosis: Fibular malleolus avulsion fracture. (It is not uncommon that these remain unattached - nonunion - and mimic an os subfibulare.)

Danis Weber B lateral view
a Danis Weber B marked b lateral view

Anteroposterior (a) and lateral (b) ankle views.
a) Obliquely-oriented curvilinear decreased densities separate both the tibial (T) and fibular (F) malleoli from their respective diaphyses. The former runs from superomedial to inferolateral, ending at the medial corner of the talocrural joint. The latter runs from superolateral to inferomedral, ending at the lateral corner of the talocrural joint.
b) The posterior malleolus (P) is intact.
Diagnosis: intra-articular, bimalleolar fractures; no evidence of diastasis (the fibular fracture is Danis Weber type B; the tibial fracture is Lauge-Hansen supination-adduction stage 2).

AP view Lateral view
a AP view marked b Lateral view marked

Anteroposterior (a) and lateral (b) ankle views.
a) Obliquely-oriented (possibly spiral) curvilinear decreased densities run through the distal fibular (F) metadiaphysis from superolateral to inferomedial, ending at the level of the syndesmosis. There is slight lateral displacement of the malleolar segment. The tibial malleolus (T) is separated from the posterior colliculus and is angulated medially. An ill-defined linear increased density is seen in the distal tibial metaphysis, corresponding to the superior margin of the displaced posterior malleolus (see b, below). The medial ankle joint space (or "gutter") is increased greater than normal.
b) The posterior malleolus (P) is separated from the tibia via an ill-defined, curvilinear decreased density, which enters the joint; the posterior malleolus is slightly displaced superiorly. The fibular malleolus segment (F) is displaced posteriorly. The talus is slightly displaced posteriorly at the talocrural joint.
Diagnosis: intra-articular, "trimalleolar" fractures with diastasis and subluxation (Danis Weber type B; Lauge-Hansen supination-external rotation stage 4).

Ap knee lateral knee
a AP ankle marked b lateral ankle marked

Anteroposterior (a) and lateral (b) upper leg views.
a) The arrow identifies a periosteal reaction along the lateral aspect of the proximal fibular metadiaphysis. Discontinuity is seen at the same location but medially (arrowhead).
b) Periosteal reaction is also seen posteriorly (arrow). The arrowhead identifies a linear decreased density that separates the head of the fibula from the remainder of the diaphysis.
Diagnosis: Maisonneuve fracture.

Ap leg/ankle lateral leg/ankle
a ap leg/ankle marked b lateral leg/ankle marked

Anteroposterior (a) and lateral (b) distal leg/ankle views.
a) The tibial diaphysis at the junction between the middle and distal one thirds diaphyses is obliquely divided into at least three segments (C). The larger distal tibial segment is displaced superolaterally. At this same level, the fibula is divided into two segments transversely; there is no apposition between the two segments, and the distal segment is displaced superolaterally, in a "bayonette" position. Diffuse, multiple curivliner decreased densities are seen throughout the distal tibial and fibular metadiaphyses.
b) The posterior malleolus (P) is separated from the tibia, accompanied by several curvilinear decreased densities throughout the distal tibia (black arrows).
Diagnosis: pilon fracture.

AP ankle lateral ankle
a ap ankle marked b lateral ankle marked

Anteroposterior (a) and lateral (b) distal ankle views.
a) The tibial malleolus, including both colliculi, is separated from the metaphysis by a transversely-oriented decreased density. The malleolar segment is slightly displaced inferiorly. Additionally, the fibula distal diaphysis is divided into two segments transversely; the distal segment is displaced laterally. The margins of bone between these two segments are very irregular.
b) The arrow indicates that the distal fibular segment is also displaced posteriorly. The posterior malleolus appears displaced superiorly with discontinuity at its articular surface.
Diagnosis: intra-articular tibial malleolus fracture; transverse distal fibular diaphyseal fracture; posterior malleolus fracture; though there is no gross evidence of diastasis, it more than likely is present (Danis Weber type C even though it is sort of transverse; Lauge-Hansen pronation-external rotation stage 4).

ankle subluxation
ankle subluation marked

Anteroposterior ankle view.
There is significant loss of apposition between the talus and tibia at the talocrural joint. The talus is displaced laterally and angulated superiorly relative to the tibia. A large gap is present between the talar medial articular surface and the tibial malleolus as well as between the lateral tibia and the fibular malleolus (not as obvious). The fibular malleolus angulates laterally relative to the diaphysis.
Diagnosis: distal fibular fracture; ankle joint subluxation; diastasis. (Weber type B, Lauge-Hansen pronation-abduction stage 3.

Should a radiographic study be ordered to assesspossible ankle fracture?

Yes, but follow the Ottawa ankle trauma guidelines.

What are the best views to order?

At a minimum order AP, mortise and/or medial oblique, and lateral ankle views.

CT may be necessary for pathology that is inconclusive on plain films.

Other information

Bone scintigraphy can be valuable when stress fracture is suspected and not yet visible on plain films.

References:

  1. Christman RA: Foot and Ankle Radiology, 2nd edition, Lippincott Williams & Wilkins, 2015.