Ankle Pathology

Radiographic findings may include:

  • a linear or curvilinear decreased density dividing a bone into two or more segments
  • ill-defined increased density
  • a concave defect of an articular surface with or without an adjacent ossicle
  • less than 100% apposition between two bones at a joint
  • uneven joint space narrowing
  • osteophytes
  • subchondral sclerosis (eburnation)

MR findings may include:

  • on T2 and STIR images, high signal intensity within or replacing tendon (normally no signal)

Podcast

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

  • Case 1
  • *Case 1
  • Case 2
  • *Case 2
  • Case 3
  • *Case 3
  • Case 4
  • *Case 4
  • Case 5
  • *Case 5
  • Case 6
  • *Case 6
  • Case 7
  • *Case 7
  • Case 8a
  • *Case 8a
  • Case 8b
  • *Case 8b
  • Case 9a
  • *Case 9a
  • Case 9b
  • *Case 9b
  • Case 10a
  • Case 10b
  • *Case 10a
  • *Case 10b
a Berndt Harty 1 AP marked b Berndt Harty 1 mediaol oblique
a Berndt Harty 1 Mortise b Berndt Harty 1 Marked

Mortise and medial oblique ankle views.
A concave defect/radiolucency (arrows) is seen along the superomedial aspect of the talar dome.
Diagnosis: Osteochondritis dissecans talar dome (Berndt-Harty type 1).

a Berndt Harty 2 AP b Berndt Harty 2 oblique
a Berndt Harty 2 AP marked b Berndt Harty 2 oblique marked

Anteroposterior (a) and medial oblique (b) ankle views.
Findings include a concave defect/radiolucency (arrows) along the superomedial aspect of the talar dome. An ossicle can be identified within this area that does not project into the joint space.
Diagnosis: Osteochondritis dissecans talar dome (Berndt-Harty type 2).

a Berndt Harty 3 AP b Berndt Harty 3 medial oblique
a Berndt Harty 3 AP marked b Berndt Harty 3 medial oblique marked

Anteroposterior (a) and medial oblique (b) ankle views.
Findings include a concave defect/radiolucency (arrows) along the superomedial aspect of the talar dome. At least two ossicles can be identified within this area that project into and appear to float within the joint space. Other findings include a fixation plate with multiple screws along the lateral aspect of the distal fibula.
Diagnosis: Osteochondritis dissecans talar dome (Berndt-Harty type 4). Post-op fixation of prior distal fibular fracture.

a Berndt Harty AP b Berndt Harty medsial oblique
a Berndt Harty AP marked b erndt Harty medial oblique marked

Anteroposterior (a) and medial oblique (b) ankle views.
Findings include a concave defect/radiolucency (arrows) along the superomedial aspect of the talar dome. An ossicle can be identified within this area that projects into the joint space.
Diagnosis: Osteochondritis dissecans talar dome (Berndt-Harty type 3).

a Pilon fracture AP b Pilon fracture lateral
a Pilon fracture AP marked b Pilon fracture lateral marked

Anteroposterior (a) and lateral (b) ankle views.
Findings include a vertical curvilinear decreased density that extends from the distal diaphysis and enters the ankle joint distally (black arrows). Cortical breaks that continue either as ill-defined increased density or curvilinear decreased density run horizontally (white arrows).
Diagnosis: Pilon fracture (Ruedi and Allgower type 1; AO/OTA type 1C).

a Pilon fracture 2 AP b Pilon fracture 2 lateral
a Pilon fracture 2 AP marked b Pilon fracture 2 lateral marked

Anteroposterior (a) and lateral (b) ankle views.
Findings include a vertical curvilinear decreased density that extends from the diaphysis and enters the ankle joint distally. Cortical breaks that continue either as an ill-defined increased density or curvilinear decreased density run horizontally through the metaphysis. The arrowheads identify another fragment along the anterior aspect of the tibia. The black arrow identifies the anterior border of the fibula, which may or may not be superimposed with another fracture line. Finally, spotty osteopenia presents throughout the extremity.
Diagnosis: Pilon fracture (Ruedi and Allgower type 2/3; AO/OTA type 2C). Acute osteoporosis.

a Ankle osteoarthritis mortise b Ankle osteoarthritis lateral
a Ankle osteoarthritis mortise marked b Ankle osteoarthritis lateral marked

Mortise (a) and lateral (b) ankle views.
Findings include uneven joint space narrowing in the mortise view (a, arrow) and anterior osteophytes in the lateral view (b, arrow). Subchondral sclerosis (SS, aka eburnation) surrounds the articulation.
Diagnosis: osteoarthritis.

a Abnormal talar tilt b normal talar tilt
a abnormal talar tilt marked b normal talar tilt marked

AP stress inversion views bilateral.
The left talar tilt angle measures approximately 25 degrees (a). It is nearly 0 degrees in the contralateral ankle (b).
Diagnosis: abnormal talar tilt left ankle (indicating tears of anterior talofibular and calcaneofibular ligaments).

a normal lateral stress b abnormal lateral stress
a normal lateral tress marked b abnormal lateral stress marked

Lateral stress views bilaterally. (Left image has been flipped to have same orientation as right ankle.)
Circles are drawn along the tibial plafond (black) and the talar dome (red). Normally, the two circles should nearly superimpose upon one another such that the talar circle is not anterior to the tibial circle, as in the left ankle (a). However, the talar circle of the right ankle (b) is dispaced (subluxated) anteriorly compared to the tibial circle.
Diagnosis: positive anterior drawer sign left ankle (indicating tear of anterior talofibular ligament). This finding correlates with the abnormal talar tilt seen in case 8a.

a Arthroigram AP b arthrogram lateral
a arthrogram AP marked b arthrogram lateral marked

Arthrogram, mortise (a) and lateral (b) ankle views.
The black arrows indicate the radiopaque contrast within the articulation, lining the cartilaginous surfaces. Contrast normally fills the anterior and posterior recesses (AR and PR, respectively) of the ankle joint in the lateral view, which is superimposed on the talus, tibia and fibula in the mortise view (SCA). Contrast is also normally seen up to the level of the tibiofibular syndesmosis in the synovial recess (SR).
Diagnosis: normal arthrogram study.

a variant arthrogram ap b variant arthrogram lateral
a variant arthrogram ap marked b variant arthrogram lateral marked

Arthrogram, anteroposterior (a) and lateral (b) ankle views.
The white arrows in the AP view (a) outline the flexor hallucis/digitorum longus tendons (markled "fhl" in the lateral view) that is filled with contrast. There is also a contrast under the tip of the fibular malleolus.
in the lateral view, the black arrows identify contrast in the posterior talocalcaneal joint. There also is some contrast material in the soft tissues anterior to the ankle at the injection site (IS).
Diagnosis: Tear of the anterior talofibular ligament. (Filling of the flexor tendons and the posterior talocalcaneal joints are variations of normal that can occur in approximately 20% & 10% of patients, respectively.)

a T1 sagittal b STIR sagittal
a T1 axial b T2 axial
a T1 sagittal marked b STIR sagittal marked

T1 (a) and STIR (b) MR sagittal plane images of the ankle. (E = vitamin E tablet marker; T = tibia; Ta = talus; Cu = cuboid)
On the T1 image (a), the expected Achilles tendon (AT) signal (low to no signal intensity, or "black") is absent and consists of intermediate signal. The Achilles tendon is only seen between its insertion to the calcaneus and the arrow, and its signal is mixed (high and intermediate).
On the STIR image (b), there is high signal intensity where the Achilles tendon is expected (AR), meaning this space is filled with fluid. The remaining Achilles tendon (AT) has retracted towards the calcaneus. High signal seen in articular areas is normal and represents synovial fluid (sf).
Diagnosis: Achilles tendon rupture.

a T1 axial marked b T2 axial marked

T1 (a) and T2 axial plane MR images of the lower leg. (E = vitamin E tablet marker; T = tibia; F = fibula)
On the T1 image (a), the expected Achilles tendon (AT) signal (low to no signal intensity, or "black") is absent and consists of intermediate signal.
On the T2 image (b), there is high signal intensity where the Achilles tendon is expected, meaning this space is filled with fluid. Fluid (ed, or edema) surrounds the entire extremity at this section.
Diagnosis: Achilles tendon rupture.

Should a radiographic study be ordered for suspicion of ankle pathology?

Yes, but follow the Ottawa Ankle guidelines.

What are the best views to order?

At a minimum order AP and lateral ankle views. Many also routinely include the mortise view with the AP. Oblique views are not necessary but can be valuable for osteochondal lesions.

Other information

MRI may be necessary for further evaluation of soft tissue pathology.

CT may be necessary to further assess pilon fractures.

References:

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