Ankle - Lateral View
How to perform the examination
Patient Positioning
Primary position (recommended): the patient is placed in the supine position with the lower limb extended and the foot internally rotated to fully expose the lateral compartment of the ankle. The foot should be maintained in a neutral or slight eversion position to optimize visualization of the fibular ligaments.
Alternative position: the patient may be positioned in the contralateral lateral decubitus position (on the opposite side) with the ankle to be examined facing upward. This position facilitates access to the lateral structures and allows dynamic inversion stress testing to assess ligament stability.
Anatomy to Identify
- Fibular malleolus (fractures, bone changes, osteophytes)
- Anterior talofibular ligament (lesions, laxity, thickening)
- Calcaneofibular ligament (changes, calcifications)
- Posterior talofibular ligament (less frequent involvement)
- Tarsal sinus (fibrosis, thickening, fat alterations)
- Peroneal tendons (secondary tendinopathies, subluxations)
Probe
High-frequency linear transducer (10–15 MHz) is essential for imaging the superficial structures of the lateral compartment. Beam steering techniques are crucial to overcome anisotropy of the fibular ligaments. Doppler is important for evaluating neovascularization in chronic ligamentous injuries and inflammatory processes. Frequency modulation allows optimization from superficial ligamentous structures to deep subtalar joints.
Anatomical Zones
Tarsal sinus
The tarsal sinus is a conical space located between the talus and calcaneus that contains interosseous ligaments, adipose tissue, and vascular structures. In hemophilic arthropathy, this region may be involved in inflammatory processes extending from adjacent joints, leading to alterations in subtalar biomechanics.
Characteristic: Conical space between talus and calcaneus, normal hyperechoic adipose content
Findings:
- Sinus fibrosis: Replacement of normal adipose tissue with hypoechoic fibrous tissue
- Thickening of interosseous ligaments: Alterations of the interosseous talocalcaneal ligaments
- Localized effusions: Fluid collections within the sinus due to extension of articular inflammatory processes
- Scar adhesions: Formation of scar tissue limiting subtalar joint movements
- Vascular alterations: Changes in the normal vascularization of the sinus with possible neoangiogenesis
Probe Positioning
Place the probe transversely and longitudinally in the depression located anterior to the lateral malleolus, between the talus and calcaneus. Optimal visualization is achieved with the foot in slight dorsiflexion and eversion.
Clinical Cases by Severity grade
The clinical cases are organized according to the HEAD-US protocol (Head-to-Head Assessment of Ultrasound Score), which classifies the severity of hemophilic arthropathy into four levels. Click on each level to explore the available cases for that specific joint–projection combination.