Lecture 3 shah radiology in foot and ankle

Imaging in foot & ankle

Dr.Rajiv ShahFoot & Ankle Surgeon

‘Foot & Ankle Orthopaedics’Vadodara, Surat, Gujarat

Ankle series X-rays

AP MortiseLateral

AP view Tibiofibular clear

space Tibiofibular

overlap Talar tilt angle Lateral talar shift Shenton’s line Arcuate line

Mortise viewMedial clear

spaceTalocrural

angleAnkle

instability sign

Ankle X-rays: 9 radiological signs!

Increased Tibio-fibular clear space Tibio- fibular overlap Talar Tilt angle

Shenton line of ankle Arcuate Line/Dime sign

Increased medial Clear Space Disturbed Talocrural angle

Lateral talar shift sign Insignificant sign!

Ankle instability sign

Larger medial clear space than superior clear (ankle joint) space

LAT X-rays

Position of talus at ankle mortisePosition of posterior malleolus

Ankle: Lateral View

Dome of the talus: centered under and congruous with tibial plafond

Posterior malleolus fractures & direction of fibular injuries can be identified

Avulsion fractures of the talus by the anterior capsule can be identified

Neutral triangle Bone quality

Bohler’s Angle 20-40 degrees Can be depressed

in both intra and extra articular fx

Limited usefulness

Ankle: Lateral View

Crucial angle of Gissane Dense cortical

bone margins of the STJ

Reconstitution is a must for calcaneal fractures

Ankle: Lateral View

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• Haglund’s deformity• Parallel pitch lines of

Pavlov

Ankle: Lateral View

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Lateral View: Posterior heel pathologies

BRODEN’S VIEW

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Broden’s View

Broden’s view:Subtalar joint assessmentfracture of calcaneus/fusions

40 deg20-30 deg10 deg

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Broden’s View: subtalar fusion assessment

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Broden’s View: subtalar fusion assessment

Harris axial view

Foot is plantar flexed, 15 degree pronated and the beam is angled 15 degree toward the head

It shows the medial column along the talar head and neck

Canale & Kelly’s View

AP

Oblique

Lateral

Foot series X-rays

Foot series: AP

Talo-First MT line (Normal = 0 degrees)

Hallux valgus Talonavicular

Coverage Angle (Normal = 0-7

degrees)Useful for planning of

treatment for AAFD

Foot series: AP

Lateral border of 1st metatarsal is aligned with lateral border of 1st (medial) cuneiform

Medial border of 2nd metatarsal is aligned with medial border of 2nd (intermediate) cuneiform

Normal Foot X-ray

Medial border of 4th metatarsal aligned with medial border of cuboid

Medial and lateral borders of the 3rd (lateral) cuneiform should align with medial and lateral borders of 3rd metatarsal

Lateral margin of the 5th metatarsal can project lateral to cuboid by up to 3mm on oblique view

Normal Foot X-ray

Diagnosis of Lisfranc injury

IM space between 1st and 2nd metatarsals is equal to space between the medial and middle cuneiforms

Diagnosis of Lisfranc injury

• The medial cuneiform-second MT space should be evaluated for the "fleck sign" indicating avulsion of the Lisfranc ligament.

Fleck sign: Lisfranc

Foot series: Lateral

Talo-First MT line(a.k.a Meary’s

line) Normal = 0

degrees Useful for

analysis for treatment of AAFD


Lateral View Superior border

of second metatarsal is continuous with superior border second cuneiform

No dorsal nor plantar displacement of metatarsal bases


SIGNS OF HINDFOOT VARUS

Increased Calcaneal pitch angle

“posterior” fibula “double talar-dome” sign “see-through” sign


Routine view Anterior process

calcaneus Cuboid -5th

metatrsal

Foot series: Internal oblique

To delineate medial column abnormalities &

injuries

Foot series: External oblique

AP Foot

Lateral Foot

Foot series: Weight bearing views

How to take weight bearing views?

Non-weight bearing

Weight bearing

Weight bearing/standing views provide stress & will demonstrate subtle lisfranc injury

Lisfranc diagnosis: Weight bearing views

1. Hallux-interphalangeal angle- nml: 6-24 deg

2. Distal metatarsal articular angle (DMAA)- nml: 6-18 deg

3. Hallux-metatarsophalangeal angle (HV)- nml: 0-20 deg

4. First intertarsal angle (IMA)- nml: < 9 deg

5. Metatarsal break angle- nml: 140 deg

6. Talocalcaneal angle- nml: 30-50 deg (child)- 15-30 deg (>5 yo)

Weight bearing relationship: AP

Weight bearing relationship: AP

1. Hallux-interphalangeal angle- nml: 6-24 deg

2. Distal metatarsal articular angle (DMAA)- nml: 6-18 deg

3. Hallux-metatarsophalangeal angle (HV)- nml: 0-20 deg

4. First intertarsal angle (IMA)- nml: < 9 deg

5. Metatarsal break angle- nml: 140 deg

6. Talocalcaneal angle- nml: 30-50 deg (child)- 15-30 deg (>5 yo)

Foot Series: AAFDWeight bearing vs. Non-weight-bearing

Weight-Bearing

Non Weight-Bearing

Disruption of angles on weight bearing xrays suggest AAFD

1. Lateral talocalcaneal angle- nml: 25-30 deg

2. 5th metatarsal base height- nml: 2.3-3.8 cm

3. Calcaneal pitch angle- nml: 10-30 deg

4. Bohler’s angle- nml: 22-48 deg

Weight bearing relationship: LAT

Weight bearing relationship: LAT

1. Lateral talocalcaneal angle- nml: 25-30 deg

2. 5th metatarsal base height- nml: 2.3-3.8 cm

3. Calcaneal pitch angle- nml: 10-30 deg

4. Bohler’s angle- nml: 22-48 deg

Midfoot projection views

Seasmoid views

Limitations of radiology

• Inter observer variations• Magnification variations• Patient to patient variations

Stress radiography is gold standard for detection of ankle instability

Anterior drawer test

Talar tilt test

Stress views

Performed by tilting the hindfoot and looking for a suction sign or asymmetric movement.

Positive stress test : talar tilt > 15 degrees side to side diff of 10.

Ankle in 20 degree of plantar flexion The tibia is pushed posteriorly against the fixed foot positive test - >0.5 to1 cm or side to side diff of 3 mm

Ankle off the edge of table

Rotated externally

Let it fallCross table viewDeltoid

incompetence

Gravity Stress views

Midfoot Stress views

Assess Fractures, stress

fractures, growth plate fractures

Neoplasms & infections

Foreign bodies Osteochondral lesions AVN Arthritis Congenital

abnormalities 3-D

reconstructions

CT Scan

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CT Scan axial, sagittal, semi coronal

Calcaneus Fracture

Lisfrancs Dislocation

Fracture Lower Tibia

CT Scan

Axial cuts across tibiofibular interval

Axial cuts at ankle mortise

Reduction Widening Rotation Fibular clear

space

Axial cut 1 cm above joint

Line from flat anterolateral surface of fibula to anterior tubercle of tibia

Must be within 2mm from anterior surface of tibia

Most reliable CT sign!

USG: Advantages

Most effective for superficial structures like tendons & ligaments

Dynamic Allows for direct palpation of painful

areas during imaging Comparison with opposite side Easy & cheap User dependent Inadequate joint visualization Poor osseous visualization

USG: Normal tendon

Tendinosis

Partial Tear

Complete Tear

USG: Tendon pathologies

Achilles tendon tear

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Ultrasound v/s MRI Magical effect Subluxating

tendon Presence of

implants/metals

STRENGTH OF US: Dynamic Evaluation of the Achilles tendon

Plantarflexion: gap in Achilles tendon narrows to less than 1 cm

Dorsiflexion: gapwidens to more than 2 cm

Achilles longitudinal

Achilles longitudinal

Peroneal tendon dislocation

--Anterior tibial tendon (yellow arrowhead) impinged by screw head (lg. white arrow) with fluid/synovitis (sm. arrows)-

STRENGTH OF US: tendon evaluation with metallic implant

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Excellent soft tissue visualization

Anatomical detailsAssessment of

TraumaNeoplasms/massesArthritis, InflammationAVNTarsal coalitionRSD

MRI

Tissue T1 T2

Cortex Low Low

Ligaments Low Low

Articular cart Intermed Intermed

Red marrow Intermed Intermed

Old blood High High

Osteomyelitis Low High

Sarcoma Low High

Marrow edema Low High

Fat High Intermed

Pus Intermed High

Strength of MRI: osteochondral lesion

Axial T2 FS Coronal PD FS Treated with screw

Strength of MRI: occult fracture

Os Trigonum Syndrome Tarsal Tunnel Syndrome Haglund’s Syndrome Os Peroneum Syndrome Anterolateral Gutter

Syndrome Sinus Tarsi Syndrome

Ankle disorders:MRI + USG

Areas of increased metabolic activities 99mTc methylene diphosphonate (MDP) Assess

Tumors & -like conditions Metabolic disorders Trauma AVN Arthritis Infection RSD

Nuclear medicine

SLIDE COURTESY: DR.SELENE PAREKH

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That’s allThank you…

Lecture 3 shah radiology in foot and ankle

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