Foot and Ankle Injuries

Foot and ankle injuries

John MacKenzie, MD Associate Professor in Residence Chief of Radiology at Mission Bay Medical Center Section Chief, Pediatric Radiology Disclosure

Research grant from General Electric Healthcare Pediatric PET MRI

T1 fat sat post gad

FDG PET Take-home message

Centers of growth are the key

to unlocking the pediatric ankle. Take-home message

Centers of growth are the key

to unlocking the pediatric ankle. Take-home message

If you want to be a BAD -SS pediatric radiologist…

Focus on the growth centers. Outline

1. Growth centers

2. Pediatric foot/ankle lesions Challenge:

We have to know a lot!

Because of the overlap with adult pathology we have to be comfortable identifying a broad spectrum of disorders. Skeletal Anatomy

Kids Adults vs. Muscles Physis Bone marrow Epiphysis Bone cortex Cartilage Apophysis Ligaments Tendons

1. Growth centers Ankle Growth Centers

Hard to see on x-ray Epiphysis

Secondary ossification center

Apophysis

Ankle Growth Centers

Epiphyseal cartilage

5 year-old Ankle Growth Centers

Secondary ossification center

5 year-old Ankle Growth Centers

Apophyseal cartilage

5 year-old Ankle Growth Centers

Apophyseal cartilage

Tendon/ligament attachment Ankle Growth Centers

Physis: weak link bone cartilage bone

weak link weak

Ankle Growth Centers Growth Ankle Physis bone cartilage bone

osseous junctions osseous - Chondro

Transitions Transitions link. are weak

Weak links Weak Ankle Growth Centers Growth Ankle

Ankle Growth Centers bone

Weak links

San Andreas fault cartilage

bone

Ankle Growth Centers

Weak links

San Andreas fault 2. Pediatric foot/ankle lesions Pediatric ankle lesions – Two flavors

1. Pediatric type 2. Adult Pediatric ankle lesions – Two flavors

1. Pediatric type 2. Adult Spectrum and overlap of injuries

Growth center at risk

Intensity of play

Growth platecloses

10 15 20

Age (years) Spectrum and overlap of injuries

Injuries to growth centers Adult-type injuries Growth center at risk

Intensity of play

Growth platecloses

10 15 20

Age (years) Spectrum and overlap of injuries

Injuries to growth centers Adult-type injuries

Growth center at risk Growth platecloses Apophyseal Achilles

avulsion tear

10 15 20

Age (years) Spectrum and overlap of injuries

Injuries to growth centers Adult-type injuries Growth center at risk

ATFL tear

Growth platecloses

10 15 20

Age (years) Physeal injury Tri-plane fracture Tri-plane fracture

S Older adolescents

H 18 month window prior to growth plate closure

Sagittal, Horizontal, and Coronal planes Asymmetric closure of growth plate

axial

coronal

Closure at 12-15 years Triplane fracture occurs during an 18 month window. Tillaux fracture – Also a transitional fx Tri-plane fracture – MIND the GAP

No gap

Intact cartilage

3D SPGRE Tri-plane fracture – MIND the GAP

> 2 mm gap

ORIF Triplane fracture – Classificaiton

2 part 3 part

Anteromedial at Kump bump

m = metaphysis e = epiphysis Triplane fracture – Treatment

Closed reduction if gap ≤ 2 mm Usually ORIF

m = metaphysis e = epiphysis Salter-Harris fracture classification

Throw some SALT on it.

I II III IV V

Same Above Low Through Why do we care about Salter-Harris?

Bone bar formation

Limb-length discrepancy Angular deformity

Normal maturation vs. bone bar after fracture of the distal tibia Bone bar vs. expected fusion

Age of fusion of tibial physis

Girls: 12-14 years Boys: 14-18 years

Fusion begins at the anteromedial undulation (Kump’s bump) 3D Cartilage MRI for Bone Bar Mapping

3D GRE 3D Cartilage MRI for Bone Bar Mapping Intact physis

Bone bars (yellow) Achilles

Maximum intensity 3D GRE projection MIP image helps direct treatment

Resection Intact physis <50% bone bridge >2 yrs growth potential

Physeal fusion

Osteotomy Bone bars (yellow) Cartilage mapping – size matters

Large Small Intact physis

Bone bars Achilles (yellow) Bone bar (black) Bones and articular surface Osteochondritis dissecans Osteochondritis dissecans Osteochondritis dissecans Unstable

Instability =

Fluid under fragment Cartilage disruption Intraarticular bodies Osteochondritis dissecans Stable Unstable

T1 fs (MR arthrogram) Medial mid foot pain Buckle fracture Buckle fracture

5 types of fractures in children

1. Epiphyseal-metaphyseal (Salter-Harris) 2. Buckle (torus) fractures 3. Hairline fractures 4. Plastic bending fractures 5. Avulsion fractures Buckle fracture

- Subtle and often overlooked

- Axial loading on a plantar flexed foot - Heal completely

- Explain child’s pain Buckle fracture

1-10 years-old

Associated with ligamentous injury at the tarsometarsal joint

Thus, considered a pediatric variant of the Lisfranc injury.

Johnson, GF. Bunk bed fracture. AJR 1981 Entrapment Impingement syndromes

Posterior (os trigonium)

Medial

Lateral

Limited ROM or deinnervation Related to bone or soft tissue abnormalities. Foot pain & paresthesias

Edematous posterior tibial nerve Tarsal tunnel - Medial impingement from ganglion

Entrapment of posterior tibial nerve (or branch) Contents of tarsal tunnel Contents of tarsal tunnel Contents of tarsal tunnel

Retinaculum

Flexor tendons Posterior tibial nerve & branches Tarsal sinus

Normal Sinus tarsi syndrome

Fibrosis Normal

Fat is replaced Sinus tarsi syndrome Sinus tarsi syndrome

Talus

Calcaneus Contents of the tarsal sinus and canal

Talus Roots of extensor retinaculum

Cervical & interosseous ligaments

Calcaneus Vessels & nerves Sinus tarsi syndrome

Usually follows inversion injury

Pain lateral aspect ankle

Sensation of hindfoot instability

Pain relieved injection sinus Sinus tarsi syndrome

Causes

Traumatic 70% Misc 30%

ganglion cysts Inflammation (JIA) PVNS Pes cavus / planus Posterior pain (left ankle)

Kager’s fat Accessory soleus muscle

Kager’s fat Pain and swelling after exercise (normal) Soft tissue mass replacing Kager’s fat Low flexor hallucis longus Any tendon + muscle can accessorize Ballet dancer with ankle pain os trigonum syndrome

Fracture passes through subtalar joint Traction / chronic repetitive injuries Impingement – Os trigonum

edema

10 year-old Os trigonum – Edema suggests irritation Asymptomatic Os trigonum mechanism – Compression vs. traction Os trigonum mechanism – Compression vs. traction Traction: Os trigonum apophysitis

Ligaments apply traction

Post. talofibular, post. tibiofibular, or interosseous ligaments may tug on ossicle. Traction: Os trigonum apophysitis

Concurrent flexor hallucis longus tendonitis

2ndary ossification center fuses w/ talar body ~ age 12 Medal pain

Tibialis posterior Painful os navicular

Accessory navicular Bone marrow edema

Imaging findings of another symptomatic skeletal variant Runner with pain

Case courtesy of Peter J. Strouse, U Michigan Traction apophysitis

Pain and swelling

Chronic / repetitive trauma

Relief in 1-6 months with rest

Case courtesy of Peter J. Strouse, U Michigan Apophysis – normal fusion

8 years-old 10 years-old

Same child over 2 years of skeletal development. 14 year old ballet dancer

STIR T1 Severs disease

Chronic repetitive injury

Focal edema post. calcaneus

Resolves with rest Severs disease DEBATE apophysitis stress reaction

Ogden JA J Ped Ortho 2004 Severs disease DEBATE apophysitis stress reaction stress fracture

Ogden JA J Ped Ortho 2004 Foot Base of fifth fracture types

Normal apophysis Pseudo Jones fx Jones fx Bone marrow

The bane of a pediatric radiologist! High-signal T2 weighted changes in bone marrow (normal)

Similar appearance at contralateral side

1-15 years

Differential diagnosis red marrow mechanics infarcts

Shabshin N, et al. Ped Rad 2008 Laor and Jaramillo. Radiology. 2009 ???

Normal maturation vs. bone bar after fracture of the distal tibia Focal periphyseal edema (FOPE)

May be painful

Tends to occur around same time of skeletal maturation

Sign of pending physeal closure?

Normal maturation vs. bone bar after fracture of the distal tibia Zbojniewicz and Laor. AJR 2011 Chronic regional pain syndrome

Chronic pain after trauma

INTENSE marrow increase in T2 & STIR

MRI may exclude other complications Sequela of trauma Insufficiency fractures Disuse bone demineralization and muscle Tendon tears and tendon atrophy Take-home message

Centers of growth are the key

to unlocking the pediatric ankle. Summary - Spectrum and overlap of injuries

Injuries to growth centers Adult-type injuries Growth center at risk

Intensity of play

Growth platecloses

10 15 20

Age (years) Summary – Unique Pediatric Anatomy

Transitions are weak links. San Andreas fault Summary – Bone marrow alternations

Normal

Pre-physeal closure

Trauma Summary – Bone marrow alternations

Normal

Pre-physeal closure

Trauma Summary – Bone marrow alternations

Normal

Pre-physeal closure

Trauma Thank you

Normal

Pre-physeal closure

Trauma