Ankle pathology

Lateral Ankle

Peroneus Tendons

Ultrasound image-Marked oedema surrounding the peroneus tendons.
Image courtesy of Nicole Booth.

Ultrasound image- Thickened peroneus longus tendon with intrasubstance tears.
Image courtesy of Michelle Williamson

Ultrasound image- Peroneus Tendonitis secondary to osteo-arthritis. Image courtesy of Michelle Williamson.

Ultrasound image- A crescenteric shaped peroneus brevis (PB) tendon is a normal variant. In this case however, the tendon is enlarges, wrapping aroud the peroneus longus (PL). There is associated calcaneofibular ligament (CFL) and tendon sheath synovium.

Peroneus Tendon Cyst

Ultrasound image- Cystic change within the peroneus brevis tendon. Longitudinal

Transverse ultrasound image- Cystic change within the peroneus brevis tendon.

Haemorrhagic tendon Sheath Effusion.

A longitudinal ultrasound view of the complex peroneus sheath effusion.

Ultrasound image- A large complex post-traumatic effusion of the Peroneus tendon sheath. Increased flow of the sheath suggests acute synovitis.

Ultrasound image- an avulsion of the peroneus brevis tendon off the base of the 5th metatarsal.

Ultrasound image- Avulsion fracture of the Peroneus Brevis off the base of the 5th Metatarsal.
The red arrow indicates the large fracture.

Ultrasound image- Partial tear of the peroneus longus tendon secondary to osteophytes at the calcaneo cuboid joint.

Abductor Digiti Minimi (ADM)

  • Runs from the calcaneum to the base of the proximal 5th phalanx with a partial insertion to the 5th metatarsal.
  • A tear or tendinopathy is differential diagnosis for 5th MT base pain.
  • If not careful, when scanning the Peroneus Brevis (PB) insertion, the operator may look too far inferior and mistake the ADM for the PB.

Ultrasound image- A differential diagnosis for avulsion of peroneus brevis is an enthesophyte and inflammation of the Abductor Digiti Minimi tendon insertion. This is slightly plantar to the peroneus brevis insertion.

Ultrasound image- Abductor Digiti Minimi.
The hypoechoic change and increased vascularity visible on power doppler, indicates acute tendinopathy.

Ultrasound image- A large enthesophyte (spur) at the abductor digiti minimi insertion.

Xray showing the abductor digiti minimi enthesophyte (‘spur’).

Transverse ultrasound view of the normal peroneus brevis insertion and the abnormal adjacent abductor digiti minimi tendon (red arrows). The blue arrow indicates an enthesophyte.


There is dispute regarding this being the ADM versus the insertion of the lateral band of the plantar fascia.

Calcaneo-Fibula Ligament (CFL)

Deep to the Peroneus tendons & inferior to the Lateral Malleolus.

Ultrasound image – Hyperaemic change within the thickened calcaneo-fibular ligament consistent with an acute process.

Loss of fibrillar achitecture and background of inversion injury indicates a tear.

Ultrasound image- Comparison of the right and left calcaneo-fibula ligaments showing marked thickening of the right.

Anterior Talofibular Ligament (ATFL)

Torn and Avulsed ATFL.

Ultrasound image- A ruptured ATFL with increased vascularity of the surrounding tissue.

Ultrasound image- Avulsion of the anterior talo fibular ligament off the fibula.

Ultrasound image- The hypoechoic area overlying this ATFL ligament is the indicator of oedema.
Adjacent to this image plane is a partial tear of the fibular origin shown with loss of fibres and increased flow on power doppler.

This is a reminder to scan through the entire structure (both bands of the ATFL).

Extensor digitorum Brevis origin

The extensor digitorum brevis origin is on the antero-lateral calcaneum.

Ultrasound image- A partial avulsion of the extensor digitorum brevis origin. Focally tender but no loss of function.

Short axis (transverse)ultrasound view of the avulsion of the extensor digitorum brevis origin.


Extensor Digitorum Tendon

Ultrasound image- Thickening of the common extensor digitorum tendon at the extensor retinaculum (white arrow). Fluid surrounds the tendon within the sheath.

Tibio fibular ligament (anterior)

The anterior-inferior ligament between the Tibia and fibula.

Ultrasound image- Acute tear of the anterior Tibio-fibular ligament.
Mouse over shows increased vascularity.

Ultrasound image- A small cortical avulsion of the tibio-fibula ligament off the tibia (red arrow).

Ultrasound image- Avulsion of the superior aspect of the tibio-fibular ligament at the syndesmosis.

Extensor Hallucis Longus Tendon

The following 4 images show a ruptured EHL tendon at the musculo-tendinous junction.

Ultrasound image- A lax, partially retracted EHL tendon. The tear is visible to the left of the image.

Ultrasound image- Transverse view of the retracted tendon and surrounding haematoma in the tendon sheath.

Ultrasound image- The muscle belly of the above EHL tear. Note the oedema and loss of normal fibrillar pattern.

A transverse ultrasound view of the oedematous retracted muscle belly.

Ultrasound image- Fluid and synovial thickening of the extensor hallucis longus tendon. Mildy increase vascularity with power doppler.
All suggestive of tenosynovitis.

Tibialis Anterior Tendon (and the Extensor Retinaculum)

Thickened Extensor Retinaculum

Ultrasound image- Thickened extensor retinaculum overlying the tibialis anterior tendon.
Comparison abnormal right V’s Normal left.

Transverse ultrasound view comparing the extensor retinaculae.
Comparison abnormal right V’s Normal left.

Ruptured Tibialis Anterior

Ultrasound image- A ruptured Tibialis anterior tendon. The blue arrow shows the insertion and the red arrow is the end of the retracted tendon. Fluid and debris is present between the two.

Ultrasound image- The proximal tendon is no longer tight, with wavy fibres now visible.

Torn Tibialis Anterior tendon secondary to Osteo-arthritis.

Ultrasound image- Osteo arthritis of the 2nd/3rd metatarso-tarsal joint impressing upon the Tibialis Anterior tendon.
Note the markedly increased vascularity associated with acute OA.

Ultrasound image- Complex tear of the Tibialis anterior tendon, secondary to marked boney degeneration of the 3rd Tarso-metatarsal jt (see previous image).

Ankle Joints and Bones


Ultrasound image- A large, simple effusion arising from the anterior ankle joint.

Ultrasound image- Synovitis of the subtalar joint.
The displaced tibialis posterior (TP) and flexor digitorum (FD) tendons are seen bowing the flexor retinaculum (RET).

On power doppler ultrasound, marked hyperaemia is isolated to the Navicular-Cuneiform joint indicating focal, acute inflammation. The Talo-navicular joint is shows no increased vascularity.

Ultrasound image- Moderate joint effusions at the cuneiform-navicular joint and the talo navicular joint.

Tarsal ligaments

There are numerous tarsal ligaments joining each adjacent tarsal bones and tarso-metatarsal bones, both dorsally and on the plantar aspect.
Always carefully investigate areas of focal tenderness.

Anatomy of the talo-navicular ligament.

Ultrasound image- Avulsion of the talar insertion of the talo-navicular ligament.

Ultrasound image- Avulsion of the talar insertion of the talo-navicular ligament.
Several small cortical fragments are visible when assessed thoroughly.

Ultrasound image- Short axis (transverse) view of the avulsed talo navicular ligament demonstrating the several small cortical fragments.


Transverse ultrasound view of the same patient (on the right) with stress fractures.
Commonly, there may be more than one site.

Ultrasound image- Stress fractures in a patient with ankle and lower leg pains following a hiking holiday.
Note the subtle, peri-osteal elevation, bowing the overlying tendon which has reactive increased vascularity.


Ultrasound showing a healing fibula fracture. The callus formation is evident. There is increased vascularity consistent with acute injury.

Xray showing the healing Fibula fracture.

Medial Ankle

The medial anatomy can be remembered as Tom, Dick And Very Nervous Harry.
= Tibialis (posterior), Digitorum, Artery, Vein, Nerve & Hallucis

Tibialis Posterior Tendon

Ultrasound image- Thickening and oedema of the tibialis posterior tendon (green) and the tendon sheath (orange).

Ultrasound image- The tibialis posterior insertion showing a normal accessory ossicle (green arrow). Be cautious not to confuse this with an avulsed fragment.

Ultrasound image- An effusion of the Tibialis posterior tendon sheath.

Ultrasound image- Pannus:
Nodular thickening of the tibialis posterior tendon sheath as seen with Rheumatoid arthritis and other chronic inflammatory conditions.

Longitudinal ultrasound view of an intrasubstance tear of the distal tibialis posterior tear.

Transverse ultrasound view of the tibialis posterior tendon tear.
Increased vascularity seen with doppler.

Deltoid Ligament

Ultrasound image- A complex rupture of the deltoid ligament with avulsed fragments (red arrows)

Ultrasound image- Deltoid ligament origin adjacent to a commonly seen, degenerative ossicle at the medial malleolus.

Posterior Ankle

  • Posterior ankle pathology relates primarily to the Achilles tendon and Kager’s fat pad.

Achilles Tendon

  • Repetitive and over-use injuries of the Achilles are common causing chronic painful palpable thickening of the Achilles tendon.
  • Acute tears of the Achilles usually present with a history of ‘rapid acceleration’ during sport. The patients will often describe that they thought someone had hit them on the back of the calf, tripping them over.
  • Due to the vascularity of the Achilles, these injuries or more common distally and in middle age.
  • Calf tears at the musculo-tendinous junction (particularly the Medial Gastrocnemius) are also common.
  • Haglund’s Deformity refers to the large calcifications arising from the calcaneum.

Haglund’s Deformity

  • Is  an exostosis of the superior border of the calcaneum, posteriorly. This may apply force to the Achilles tendon increasing the risk of tendinopathy.
  • Should not be confused with an Achilles insertional calcaneal spur which does NOT necessarily indicate pathology or be responsible for symptoms.

Ultrasound showing the site of a Haglund’s deformity. A calcaneal spur is present with central Achilles tendinopathy seen as hypoechoic change (highlighted in yellow)

Achilles thickening and oedema.

Ultrasound image- Panoramic View showing the fusiform thickening typical of Achilles tendonosis.

Ultrasound image- The insertion is mildly thickened, but intact.
Marked thickening of the mid-distal tendon is visible, beginning on the left of the image.

Intrasubstance achilles tear and oedema.

Longitudinal view shows the fusiformly thickened achilles tendon with intrasubstance tears seen as hypoechoic zones (highlighted in blue)

Transverse ultrasound view showing the small intrasubstance tear within an edematous achilles tendon.

Partial achilles tear and Kager’s fat pad oedema.

Ultrasound image- A partial tear of the Achilles (green arrowheads) with associated  inflammation of the underlying Kager’s fat pad (red arrows).

Oedema (blue arrow).

Power doppler shows mildly increase vascularity.

Ruptured Achilles

A panoramic ultrasound view of a rupture of the mid Achilles tendon.
The red arrows indicate the retracted tendon ends.

A transverse ultrasound view through the distal retracted tendon with surrounding oedema.

A panoramic ultrasound view of the achilles avulsion.
Red arrow: Avulsed fragment.
Green arrows: Lax, retracted proximal tendon.

A panoramic ultrasound view of a rupture of the mid Achilles tendon.
The red arrows indicate the retracted tendon ends.

Ultrasound image- A large avulsion of the distal Achilles insertion with a calcaneal fragment.
The following image is a panoramic view of this injury.

A panoramic ultrasound view of the achilles avulsion.
Red arrow: Avulsed fragment.
Green arrows: Lax, retracted proximal tendon.

Achilles Calcification/ Calcific Tendinosis

  • Calcification within the achilles tendon indicates chronic disease/old trauma.

Ultrasound image- Calcifications within a heterogenous, poorly defined distal achilles tendon. Note the lack of fibrinous architecture of the tendon.

Transverse ultrasound view of the Achilles calcifications.

Ultrasound image- Both intrasubstance calcifications and calcification of the para-tenon in a patient with chronic tendonitis.

Ultrasound image- Dense calcifications from the musculo-tendinous junction to the insertion. These were readily seen on xray.

Fatty Involution

Fatty involution of muscles is the result of atrophy from chronic underuse.

Ultrasound image-Transverse mid calf:
The diffusely echogenic, attenuating calf muscles in a patient with chronic achilles tendinosis. Apart from addressing the Achilles pathology, this patient will need extensive rehabilitation on their calf muscles

Longitudinal ultrasound view of the distal medial gastrocnemius muscle.
The normal fibrillar architecture has been replaced by a diffusely echogenic ‘cloudy’ appearance.
Atrophy with fatty involution/replacement.

Ultrasound image-
Haglund’s deformity (red arrow).
Thickened Achilles insertion (blue arrow).

Retro-calcaneal (Kager's) Fat Pad

The fat pad should be predominantly hypoechoic. If inflammed it will have increased echogenicity, slight fluid and lose the fatty definition. There will often be increased flow on colour/power doppler.

Power doppler ultrasound demonstates the markedly increased vascularity of both the Achilles and Kager’s fat pad.

Ultrasound image- Comparison of the retrocalcaneal fat pads. Normal left and oedematous right, highlighted in green when you hover your cursor over. The Achilles is also mildly thickened.

Ultrasound image- A partial tear of the achilles (green arrowheads)
Associated damage (blue arrow) to Kager’s fad pad and associated inflammatory change (red arrows)

Plantaris Tendon

  • The Plantaris is also referred to as the ‘monkey muscle’ and is the leg equivalent of the Palmaris Longus in the anterior forearm/wrist.
  • These tendons are often harvested for use as grafts in tendon repairs.
  • Often mistakenly diagnosed as an Achilles tendon tear.

Plantaris Rupture ultrasound image.

  • The plantaris muscle originates from the posterior lateral femoral condyle next to the head of the lateral gastrocnemius muscle.
  • It lies between the medial gastrocnemius muscle belly and the soleus muscles. It travels obliquely in the calf. The thin tendon inserts into the achilles tendon.
  • Usually a patient will complain that they felt a snap or a feeling that someone kicked them in the back of leg. There can be bruising around the ankle.