Musculoskeletal Ultrasound of the Foot And Ankle

Arthur Jason De Luigi, DOProgram Director, Sports Medicine Fellowship

Director of Sports MedicineMedStar National Rehabilitation Hospital MedStar Georgetown University Hospital

Disclosure

• Nothing to Disclose

OBJECTIVES

• General Survey• Anteromedial• Superior• Posterior• Pathology• Injections

TABLE OF CONTENTS

• General survey• Anterior• Lateral• Medial• Posterior

General survey

• Complex anatomy: > 26 bones, 33 joints

• Conceptual construct– Hindfoot: tibia, fibula, talus,

calcaneus, ankle and subtalar joint– Midfoot: cuboid, navicular,

cuneiforms; arches of the foot supported by static and dynamic arch stabilizers

– Forefoot: metatarsals, phanges

Functional units

• Ankle• Transverse tarsal joint

complex– Calcaneocuboid– Talocalcaneonavicular

• Tarsometatarsal joint (Lisfranc)

TABLE OF CONTENT

• General survey• Anterior• Lateral• Medial• Posterior• Plantar

Dorsum

• Tibialis anterior• Extensor hallucis longus• Extensor digitorum longus• Deep peroneal nerve and dorsalis pedis artery• Anterior joint recess (effusion, loose bodies,

and synovial thickening)• Anterior joint capsule

Extensors of ankle

• Crossing anterior to the ankle– Tibialis anterior (TA)– Extensor hallucis longus (EHL)– Extensor digitorum longus– Dorsalis pedis artery and vein– Deep peroneal nerve

• Place probe in transverse axis to the tibia on anterior ankle near the joint line

Anterior ankle• TA

– Most medial• EHL• Dorsalis Vasculature (a,v) • EDL

– Most lateral • Each tendon is enclosed

within its own tendon sheath• Deep peroneal nerve (s)

– Close proximity to the vascular bundle

• The inferior extensor retinaculum (6) lies superficial

• Both EHL and EDL have low-lying myotendinous junction.

• Muscle belly comes in view quickly as the transducer is moved proximally

Tibialis anterior

• Turn transducer to long-axis to tibia and place over TA at level of the ankle

• TA is superficial to the anterior ankle joint recess, which is filled with fat (f).

• The cartilage (6) appears as hypo/anechoic layer superficial to the talar dome (TD)

Tibialis insertion

• Trace probe along the TA tendon to see its insertion on the inferior aspect of medial cuneiform and the base of 1st metatarsal

Extensor Hallucis Longus (EHL)• Origins at anterior surface of the

fibula and interosseous membrane for about the middle two-fourths of its extent, passes under the inferior extensor retinaculum (cruciate crural ligament) and inserts on base of great toe distal phalanx

• Extends the great toe, invert and dosiflex the foot

EHL• Return to distal tibia over TA tendon in long-axis and

move laterally; • EHL is the next tendon in view• The body of EHL (**) can be seen in supramalleolar region

EHL over dorsal midfoot• Following the EHL over talar neck (T),

navicular (N) and medial cuneiform (MC)

EHL insertion

• Trace distally over the course of the great toe

• EHL inserts at base of distal phalanx– An anatomical variation of EDB may send a

tendon and insert on base of proximal phalanx, known as extensor hallucis brevis, or EHB (^)

Extensor Digitorum Longus (EDL)• Originates from anterior lateral

condyle of tibia, anterior shaft of fibula and superior ¾ of interosseous membrane

• Tendons contained within single tendon sheath until divide superficial to EDB

• Inserts on dorsal surface of middle, and distal phalanges of lateral four toes

EDL

• Level of the ankle joint recess. The inferior extensor retinaculum (h) is superficial to the tendon

• Joint recess is visible superficial to the talar dome cartilage (6)

Lisfranc Joint

• Important for mid foot stability • Skeletal elements:

tarsometatarsal, intertarsal, and intermetatarsal articular surfaces

• Non-skeletal elements: articular capsules, the various ligaments

Lisfranc ligament

• Complex of ligament which extends from plantar-lateral aspect of medial cuneiform, passes in front of the intermediate cuneiform ligament, and inserts into the plantar-medial of second metatarsal

• Oblique band connecting 2nd metatarsals (M2) and intermediate cuneiform (C2) to the medial cuneiform (C1) most important

• Reinforces bony stability of base of the 2nd metatarsal between medial and lateral cuneiforms

Dorsal Lisfranc ligament

• Place transducer in transverse axis over dorsal medial foot over first and second metatarsal (M1, M2)

Dorsal Lisfranc ligament

• Move proximally until medial cuneiform (C1) is seen, which appears angular instead of round compared to metatarsals

• Lisfranc ligament (arrow) appears hyperechoic and fibrillar, with a characteristic notch in C1 at its attachment

• C1 and M2 distance (arrowhead) should be minimal to none

TABLE OF CONTENT

• General survey• Anterior• Lateral• Medial• Posterior• Plantar

Lateral

• Peroneus brevis• Peroneus longus• Superior peroneal retinaculum• Anterior TaloFibular Ligament (ATFL)• Calcaneo-Fibular Ligatment (CFL)

Peroneus groups

• Peroneus longus (PL)– Originates at head of fibula, wraps

around cuboid laterally and enter deep space of foot, inserting on medial cuneiform and 1st metatarsal

• Peroneus brevis (PB)– Originates at proximal 1/3 of fibula,

inserts on base of 5th metatarsal• Both tendon wraps around posterior

lateral malleolus before parting ways at peroneal tubercle (aka trochlear process) on lateral aspect of calcaneus

Lateral ankle ligaments• Anterior talofibular ligament (ATFL)

– Most frequently injured structure in lateral ankle sprain

– Generally two separate bands– Loose during foot neutral and taut when

foot plantarflexed and inverted, subject to injury

• Calcaneofibular ligament (CFL)– The only ligament bridging both the

talocrural joint and subtalar joint – Remain taut throughout entire ROM

• Posterior talofibular ligament (PTFL)– Difficult to visualize on US– Relaxed in neutral and plantar flexion, taut

in dorsiflexion

1 Tip of the lateral malleolus2 Tibia3 Anterior tibiofibular ligament 4 Distal fascicle of the anterior tibiofibular ligament5 Superior band of the anterior talofibular ligament6 Inferior band of the anterior talofibular ligament

7 Lateral articular surface of the talus8 Neck of the talus9 Head of the talus10 Calcaneofibular ligament11 Talocalcaneal interosseous ligament12 Cervical ligament13 Talonavicular ligament14 Navicular

Peroneus group, supramalleolar• Place transducer on

transverse axis over lateral ankle just proximal to lateral malleolus

• Peroneus longus (PL) is superficial to the body of peroneus brevis (PB), with the PB tendon (^) forming just deep to PL tendon

Peroneus group, retromalleolar

• PB – Condensed into mostly

tendon, and stays deep to PL as the tendons course around the malleolus

• Superior peroneal retinaculum (^) – connects calcaneus to

fibula (F) and may be visible• PTFL (↓) is deep to the

peroneal tendons

Peroneus group, inframalleolar

• Place transducer over tip of fibula

• Deep to the inferior peroneal retinaculum (^), PL and PB may appear oblique as they diverge toward peroneal tubercle

• The calcaneofibular ligament (6) connects fibula and calcaneus

Peroneal tubercle

• Move transducer slightly caudal and locate the

• Peroneal tubercle (*)– which appears like a peak on

the surface of calcaneus• Deep to the inferior

peroneal retinaculum (^), PL (g) and PB (a)

• Generally divides around PT with PB maintains superior and PL dives inferior, as seen in the top sonogram

Peroneus brevis insertion

• Place transducer over lateral aspect of base of 5th metatarsal (5MT) in longitudinal axis, PB can be seen inserting onto the base

Peroneus Longus (PL)

• PL (s) tendon dives around cuboid (Cu) and travels deep until reaching 1MT base, together with TP forming a tendinous stirrup– Start at the lateral border of foot at cuboid, scan in longitudinal axis with PL toward 1MT

• Plantar aponeurosis (^) is seen superficial to FDB• FHL tendon appears hypoechoic given its oblique course in this view

Anterior TaloFibular Ligament (ATFL)• Place transducer in

transverse axis over anterior surface of fibula parallel to the plantar surface of the foot

• ATFL (*) connects between fibula (F) and talus (T), deep to the superior extensor retinaculum (^)

Anterior tibiofibular ligament• Move transducer

cephalad until tibia (T) comes in view in close proximity to the fibula

• Anterior tibiofibular ligament (*) is flat and broad, inserting slightly obliquely from tibia onto fibula

TABLE OF CONTENT

• General survey• Anterior• Lateral• Medial• Posterior• Plantar

Medial

• Posterior tibialis• Flexor digitorum longus• Posterior tibial nerve• Tibial artery and veins• Flexor hallucis longus

Tarsal tunnel

• Roof: flexor retinaculum

• Floor: tibia and talus and more inferiorly the medial aspects of the navicular and calcaneus

• Content: tibialis posterior (TP), flexor digitorum longus (FDL), tibial vasculature, tibial nerve, flexor hallucis longus (FHL)

Tarsal tunnel, proximal ankle• Transducer in transverse axis posterior to medial malleolus• From anterior to posterior, TP is followed by FDL, the tibial veins (v) and

artery (a), tibial nerve, then finally FHL • (Tom, Dick and A Very Nervous Harry).

• Achilles tendon (A) is barely visible at the edge of field• At this level, most of FHL is hypoechoic muscle belly (dotted line); the

hyperechoic tendon can be difficult to distinguish

Tibialis posterior

• Place transducer in longitudinal axis with TP tendon• The tendon sheath for TP is clearly visible• At this level, TP travels with FDL; FHL is lateral to TP and

FDL

Tibialis posterior insertion

• Tracing TP pass the sustentaculum tali (ST) toward its insertion at navicular (N); note the tendon appears hypoechoic

• The hyaline cartilage (6) of talar head (Tal) appears as a hypoechoic layer

Flexor Digitorum Longus (FDL)

• Tracing the FDL distally, the tendon crosses the joint between talus and sustentaculum tali of calcaneus before curving and diving deep into the plantar surface

Flexor Hallucis Longus (FHL)

• Turning the transducer to longitudinal axis in retromalleolar region, then short-axis slide posteriorly around the TP and FDL tendons to reveal the FHL tendon

• FHL tendon is surrounded by fat pads (*), and its tendon sheath appears hyperechoic

TABLE OF CONTENT

• General survey• Anterior• Lateral• Medial• Posterior• Plantar

Posterior

• Achilles tendon and paratenon• Plantaris tendon (as indicated)• Retrocalcaneal bursa• Retro-Achilles/Superficial Achilles bursa• Dynamic scanning in of Achilles (as indicated

to assist with tear evaluation)

Achilles tendon

• Confluence of gastrocnemius and soleus, and inserts on calcaneus

• Also accepts plantaris tendon• Strongest tendon in the body, and

frequently injured• Surrounded by paratenon, a thin

layer of vascular tissue, without tendon sheath—always abnormal if surrounded by fluid

Gastrocnemius-Soleus longitudinal

• Start with proximal calf in longitudinal axis & scan distally• Achilles tendon (A) can be seem forming as the

gastrocnemius (G) and soleus (S) converge into tendons• Traumatic tear of the gastroc may be a source of calf pain

Gastrocnemius-Soleus transverse distal

• Sliding distally, the Achilles tendon (A) starts to converge superficial to gastroc, and lateral gastroc bulk gives away to mostly medial gastroc (MG)

• The transverse intermuscular septum (^) separates soleus (S) from deep posterior compartment muscles (FDL, FHL, TP)

Achilles, longitudinal

• Place transducer in longitudinal axis over Achilles tendon• Achilles (A) is thick, fibrillar and hyperechoic, inserting on

calcaneus. Hyperechoic paratenon (^) can be observed• Anterior to the Achilles is Kager’s fat pad (K)• Retrocalcaneal bursa may exist posterior to Achilles tendon

Achilles, horizontal

• Stand-off gel can help to reduce artifact• Achilles tendon (A) should be fairly homogeneously

hyperechoic, superficial to the Kager’s fat pad. Plantaris tendon (*) maybe visible as its distinct entity

TABLE OF CONTENT

• General survey• Anterior• Lateral• Medial• Posterior• Plantar

Plantar surface

• Plantar Fascia• Dynamic scanning• Applying pressure for Morton’s neuroma,

and/or ultrasonographic Mulder’s click (as indicated)

Plantar aponeurosis

• Strong fascia, connecting from calcaneus to plantar plantar plant of metatarsal heads

• Three distinct bands– Central: thickest, attached to calcaneal tuberosity,

divides into fascicles for each toes distally insert into MTP and flexor tendons

– Lateral: attaches to medial process of the calcaneus – Medial: thinnest, covers AbH

• Contribute to maintenance of both longitudinal and horizontal arches

Plantar aponeurosis, PQ

• Place transducer in long axis over calcaneal tubercle

• Plantar aponeurosis (s) is robust, superficial to FDB and PQ

SUMMARY

• Complex anatomy, complicated by the depth and the crossing of tissue planes

• Dynamic examination of tendons helpful• Proper selection of transducer to maximize

resolution at depth and maneuverability in exam

• Practice makes perfect

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