Ankle - Posterior View
How to perform the examination
Patient Positioning
Primary position (recommended): the patient is placed prone with the feet extending beyond the edge of the examination table to allow complete relaxation of the Achilles tendon. Alternatively, the patient may be positioned supine with the knee flexed and the foot resting on the table to expose the posterior surface of the ankle.
Alternative position: the patient may be placed in a lateral decubitus position with the ankle to be examined facing upward. This position facilitates access to the postero-medial and postero-lateral structures and allows dynamic examination through dorsiflexion–plantar flexion movements.
Anatomy to Identify
- Achilles tendon (tendinopathy, calcifications, partial/complete tears)
- Retrocalcaneal bursa (bursitis, thickening, calcifications)
- Subcutaneous calcaneal bursa (superficial inflammation)
- Posterior synovial recess (effusions, synovial thickening)
- Posterior calcaneus (bony changes, spurs, erosions)
- Posterior process of the talus (fractures, impingement)
Probe
High-frequency linear transducer (7–12 MHz) is essential for imaging the superficial posterior structures. It is crucial to use techniques to overcome Achilles tendon anisotropy by employing multiple angulations. Doppler is essential to assess neovascularization in tendinopathies and inflammatory processes of the bursae. Frequency modulation allows optimal analysis from superficial tendinous structures to deep posterior joints.
Anatomical Zones
Achilles tendon
The Achilles tendon represents the terminal convergence of the triceps surae muscle and inserts onto the posterior tuberosity of the calcaneus. In hemophilic arthropathy, this tendon may develop significant structural changes due to biomechanical compensations and chronic stress resulting from alterations in the tibiotalar joint.
Characteristic: Length: 12–15 cm; Thickness: 5–7 mm; Parallel fibrillar structure
Findings:
- Compensatory tendinopathy: Tendon thickening with loss of normal fibrillar echotexture due to functional overload
- Intratendinous calcifications: Calcific deposits along the tendon, particularly in the distal portion
- Insertional enthesopathy: Alterations at the calcaneal insertion with posterior bony spur formation
- Partial tears: Fiber discontinuities due to degeneration of weakened tissue
- Neovascularization: Increased intratendinous vascularization detectable with Doppler imaging
Probe Positioning
Place the probe longitudinally along the entire course of the tendon, from the myotendinous junction to the calcaneal insertion. The marker should be oriented proximally toward the calf. Perform transverse scans as well to fully assess tendon morphology.
Retrocalcaneal bursa
The retrocalcaneal bursa is a synovial structure located between the Achilles tendon and the posterior surface of the calcaneus. In hemophilic arthropathy, this bursa may become involved in inflammatory processes extending from adjacent joints or develop primary changes due to biomechanical alterations of the ankle.
Characteristic: Virtual space under normal conditions; distensible in the presence of effusion
Findings:
- Chronic bursitis: Thickening of the bursal walls with recurrent effusions containing blood products
- Parietal calcifications: Calcific deposits in the bursal walls due to chronic inflammation
- Adhesions: Loss of normal mobility between the tendon and calcaneus with scar tissue formation
- Calcaneal erosions: Irregularities of the posterior calcaneal surface caused by chronic pressure
- Articular communication: Possible connection with the posterior tibiotalar joint
Probe Positioning
Place the probe longitudinally between the Achilles tendon and the posterior surface of the calcaneus. Optimal visualization is achieved with the foot in dorsiflexion to open the retrocalcaneal space.
Posterior recess
The posterior recess of the tibiotalar joint extends posteriorly between the distal tibia and the talus, behind the malleoli. In hemophilic arthropathy, this recess is a preferential site for hemorrhagic effusion and synovial proliferation, particularly during acute phases of the disease.
Characteristic: Posterior extension of the synovial cavity, normally collapsed
Findings:
- Posterior hemorrhagic effusions: Synovial fluid collection with internal echoes in the posterior portion of the joint
- Synovial thickening: Proliferation of the synovial tissue with heterogeneous echotexture in the posterior recess
- Posterior impingement: Compression of posterior structures during plantar flexion due to synovial thickening
- Loose bodies: Osteochondral fragments within the posterior recess resulting from articular erosions
- Capsular fibrosis: Thickening and retraction of the posterior capsule causing limitation of dorsiflexion
Probe Positioning
Perform transverse and longitudinal scans of the posterior portion of the tibiotalar joint, positioning the probe medially and laterally to the Achilles tendon to visualize the posterior synovial recesses.
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.