tips for interpreting x ray in trauma

TIPS FOR

INTERPRETING X-

RAYS IN TRAUMA

KENG SHENG CHEW, MD, MMED (Emerg Med)

Senior Lecturer/Emergency Medicine Physician,

School Of Medical Sciences, Universiti Sains Malaysia

CERVICAL SPINE

• In patients with major trauma – 5% have an unstable cervical spine

– 2/3rd of this 5 percent present without initial neurologic deficit.

• Chiles III BW, Cooper PR. Acute Spinal Injury. New England Journal of

Medicine 1996; 334 (8):514-20.

• Site of Injuries: Cervical spine (60%), Thoracolumbar junction (20%), Thoracic (15%), Lumbosacral Spine (5%)

• Savitsky E, Votey S. Emergency Department Approach To Acute

Thoracolumbar Spine Injury. The Journal of Emergency Medicine 1997; 15 (1):49-60.

CERVICAL SPINE

• Ensure visualization of ALL cervical vertebrae as well as the atlanto-occipital and C7-T1 articulations

• Cervical region – most commonly injured part due to

– its flexibility (most mobile) and

– its exposure

• Savitsky E, Votey S. Emergency Department Approach To Acute Thoracolumbar Spine Injury. The Journal of

Emergency Medicine 1997; 15 (1):49-60.

• A = smooth, unbroken alignment

of three lines

INTERPRETING CERVICAL X-RAY

• Look at:

• A = Alignment

• B = Bones

• C = Cartilaginous and

• S = soft-tissues

Mnemonic:

„ABCs‟

ALIGNMENT

CASE STUDY

A 41-year-old man was

brought to the ED

following a motor vehicle

collision in which he was

an unrestrained driver

whose vehicle hit a

roadway median divider.

The automobile driver‘s

air bag deployed.

HANGMAN FRACTURE

The usual site of fracture

is because it is the

weakest part of the C2

neural arch.

THE „TRUE‟ HANGMAN FRACTURE VS

ASPHYXIATION DUE TO HANGING

HANGMAN FRACTURE

HANGMAN FRACTURE

The typical mechanism of injury causing hangman‘s fractures.

Hyperextension and axial compression occur when the head impacts

on the windshield. This fractures the posterior skeletal elements of

the cervical spine.

PSEUDOSUBLUXATION

• Malalignment of the

posterior vertebral

bodies is more

significant than that

anteriorly

• Two most common

causes of C2-C3

malalignment are

pseudosubluxation and

hangman's fracture.

PSEUDOSUBLUXATION

• To distinguish these

two, draw a Swischuk

line from the base of

spinous process of C1

to the base of the

spinous process of C3.

• The base of C2 should

normally not be more

than 2 mm from the

Swischuk line

*

*

*

HANGMAN FRACTURE

DISTANCE >3 CM

BONES

• Vertebral bodies below

C2 have a uniform,

square (cuboidal)

shape.

• An increase in density

may indicate a

compression fracture.

CARTILAGINOUS STRUCTURES

• The intervertebral spaces

should be uniform.

• Widening of these or the

interspinous distance may

indicate an unstable

dislocation.

• An increase in

interspinous distance of

50% suggests ligamentous

disruption.

SOFT TISSUES

• Prevertebral soft

tissue

• C1 – C4: 50% of the

AP width of a vertebral

body

• C5 – C7: the AP width

of one vertebral body

‗2 – 6‘ Rule

C2 = 6 mm

C6 = up to 2 cm

PRE-DENTAL SPACE

• Predental Space < 3

mm in adult

• < 5 mm in children

• Widening of predental

space – suspect

Jefferson‘s fracture of

C1

PRE-DENTAL SPACE

JEFFERSON FRACTURE

A 37-year-old man lost his

balance while standing on a

subway platform and fell five

feet, head first onto the tracks.

He had consumed an alcoholic

beverage prior to his fall.

Fortunately, train was not

entering the station at the time.

He was extricated from the

tracks, immobilized, and brought

to the ED.

JEFFERSON FRACTURE

JEFFERSON FRACTURE

Increased

Predental

space

Normal Predental space

THE OPEN MOUTH VIEW

OPEN MOUTH VIEW

• The distance between the odontoid and the lateral

masses of C1 should be equal.

• Inequality may be due to head rotation.

It A + B >7 mm, this

suggests a disruption

of the transverse

ligament

PREDENTAL SPACE ABNORMALITIES

Predental space

distance

Significance

3 – 6 mm Partial disruption of the

transverse ligament

6–10 mm Disruption of the

transverse ligament, but

intact alar and

Accessory ligaments

> 10 mm Complete

ligamentous instability

CHEST X-RAY

CHECKLIST FOR A CXR

• Name, ID particulars, etc

• Check for the ‗L‘ or ‗R‘ marker.

• To prevent missing dextrocardia

• Quality of the film

• Is the film well-centered?

• Is the patient‘s position rotated?

• Is the exposure and X-ray penetration adequate?

IS IT AP or PA VIEW?

CRITERIA PA VIEW AP VIEW

Spinous process

lamina

Prominent

inverted ‗V‘

shape

Straight

Scapula Out of the chest

wall

Inside

Clavicle direction Medial end is

lower

Straight

Heart size Not enlarged Appears enlarged

CHECKLIST

• Penetration – the spine should be ‗just seen‘

through the mediastinum

• Well-centeredness – the medial ends of the

clavicicle should be equa-distant from

midline

• Exposure - scapular end should be outside of the

lung fields

• In full inspiration, 6th anterior or 10th posterior rib

should touch the hemidiaphgram

DISTORTIONS ON A PORTABLE AP X-RAY

• Rotated positioning of the patient—apparent shift of

trachea and mediastinum

• Poor inspiration—crowded lung markings at the

bases

• Suboptimal exposure—over or under-penetrated

• Cardiac enlargement

• Widened and indistinct mediastinum

• Superimposed extrathoracic objects—spine

immobilization boards, tubes, monitoring wires, and

clips

A WELL-CENTERED X-RAY FILM

A

ROTATED

FILM

The patient

is rotated to

which side?

THREE ZONES LEVEL OF THE LUNG FIELD

ZONE LEVEL

Upper zone/apices Apical region to 4th

posterior rib

Mid-zone 4th to 8th posterior rib

Lower zone From 8th posterior rib

downward

HILA

• The hila is formed by

the pulmonary veins

with the lower lobe

arteries superimposed.

• Left hila is higher than

right hila by 1 cm

• Left hila has a ‗square‘

shape, right a V-shape

MEDIASTINUM STRUCTURES

PARA-TRACHEAL

STRIPE

• The right paratracheal stripe

is a thin layer of connective

tissue that lies along the

right tracheal wall adjacent

to the right lung.

• It is normally no more than 5

mm thick.

• Widening >1 cm is a sign of

pulmonary venous

hypertension (e.g., CCF)

HEMIDIAPHRAGM

• The highest point of the right diaphragm is usually

1–1.5 cm higher than that of the left. Each

costophrenic angle should be sharply outlined.

ASSESSING FOR FLATTENING OF

HEMIDIAPHRAGM

• The highest point of a hemidiaphragm should be at

least 1.5 cm above a line drawn from the

cardiophrenic to the costophrenic angle.

Remember: Tension pneumothorax is a clinical

diagnosis, NOT a radiological diagnosis

When the patient is supine, a pneumothorax collects anteriorly and

may be impossible to detect. A large pneumothorax may widen the

costophrenic sulcus—the ―deep sulcus‖ sign

Deep sulcus sign:

abnormal deepening

and lucency of the

left lateral

costophrenic angle

QUANTITATIVE MEASUREMENT OF

PNEUMOTHORAX SIZE

Rhea (1981): Ptx % = 5 + 9* AID (after

Choi 1998)

Collins (1995): Ptx % = 4 + 14 * AID

Light formula: Ptx % = (1 - x3/y3)*100

ACCP (2001): ―small‖ a < 3 cm; ―large‖

a 3 cm

BTS (2003): ―small‖ m < 2 cm; ―large‖ m

2 cm

where Average interpleural

distance (AID) = (a+b+c)/3

QUALITTATIVE CLASSIFICATION

• More recent guidelines have proposed using single

measurements to determine patient care.

• Only two sizes of pneumothorax are distinguished:

small and large.

• Small pneumothoraces can be managed by

observation, as long as the patient is stable, has

only mild symptoms, and has no underlying lung

disease.

• Large pneumothoraces need chest tube or catheter

aspiration to reexpand the lung.

DIFFERENCES BETWEEN ACCP VS BTS

GUIDELINES

• The American College of Chest Physicians

(ACCP) proposed using an apex to cupola

distance of 3 cm to distinguish small from

large pneumothoraces

• The British Thoracic Society (BTS) uses an

average pneumothorax width of 2 cm to

distinguish large from small

pneumothoraces, although the exact method

of measurement is not specified.

RADIOLOGIC FEATURES DUE TO

MEDIASTINAL HEMATOMA

• Wide mediastinum

• Indistinct or distorted aortic knob or proximal

descending aorta

• Opacification of the aorticopulmonary

window

• Wide right paratracheal stripe

• Left paraspinal line displaced and extending

superior to aortic knob

RADIOLOGIC FEATURES DUE TO

MEDIASTINAL HEMATOMA

• Left apical pleural cap

• Right paraspinal line displaced

• Mass effect due to periaortic blood at the

aortic arch

• Trachea or nasogastric tube displaced to the

right

• Depressed left mainstem bronchus

AORTIC DISSECTION

AORTIC DISSECTION

MECHANISMS OF AORTIC INJURY

MECHANISMS OF AORTIC INJURY

PELVIC X-RAY

2 – 4 mm

< 5 mm in adults

< 10 mm in

adolescents

CHECKLIST FOR PELVIC X-RAY

• Look for symmetry of the hemipelvis

• Scrutinize the three ‗rings‘ for fractures

– Main pelvic inlet

– Obturator foramen

• Sacroiliac joints

– Normal width 2 – 4 mm

• Symphysis pubis

– < 5 mm in adults

– Up to 10 mm in children

– Superior surfaces should align or offset < 2 mm

• Look for special radiographic landmarks

• Iliopubic line

• Ilioischial line

• ‗U‘ curve and teardrop sign

• Shenton line

CHECKLIST FOR PELVIC X-RAY

RADIOGRAPHIC LANDMARKS OF PELVIC

X-RAY

RADIOGRAPHIC LANDMARKS OF PELVIC

X-RAY

Radiographic “U” is the

inferior lip of the anterior

articular surface of

acetabulum.

Radiographic teardrop

is composed of the

ilioischial line, the

acetabular articular

surface, and the

radiographic ―U.‖

RADIOGRAPHIC LANDMARKS OF PELVIC

X-RAY

THE SHENTON LINE

• It is an imaginary

line drawn along

the inferior border

of the superior

pubic rami

(superior border of

obturator foramen)

and along the

inferiomedial

border of the neck

of femur. The line

should be smooth

and continuous

MAXILLO-FACIAL X-RAY

THE WATERS VIEW

• Also known as

Occipito-mental view

(O-M view)

• The Waters view is the

most important view

and by itself is probably

a sufficient screening

radiograph for patients

with facial injuries.

Occipito-frontal view

To visualize frontal sinuses, superior

orbital rim, and ethmoid air cells

DOLAN‟S LINES

WATERS VIEW (OM VIEW)

LE FORT

FRACTURES

McGrigors Lines

WRIST AND HAND X-RAY

WRIST ARCS (PA VIEW)

Approximately equal distance (usually 1

to 2 mm) between each of the carpal

bones

Three arcuate lines can be

drawn along the carpal

articular surfaces

1. Disruption of these curves or

2. Widening of the carpal spaces

implies carpal ligament disruption

and carpal instability

THE TERRY THOMAS SIGN

Scapholunate dissociation

SCAPHOID FRACTURE

• Most common carpal fracture (more than 60% of all

carpal fractures)

– Highest incidence of avascular necrosis of carpal bone –

Lunate Fracture (Keinbock‘s disease)

– (Note: Most common wrist fracture - Distal radius)

• Commonly seen in young adults age 15 to 30 and

occurs after a fall on the outstretched hand

• Rare in skeletally immatured individuals because of

the relative weakness of distal radius compared to

scaphoid

COLLES‟ FRACTURE

A - showing Posteroanterior

view shows fracture and

shortening of radius

B - Lateral view shows typical

dorsal displacement and

angulation of radial fracture. (From Propp DA, Chin H: Forearm and

wrist radiology

SMITH‟S FRACTURE

Open reduction usually

necessary.

Closed reduction often

unsuccessful due to

flexor muscle pull.

BARTON FRACTURE

Barton‘s fracture is an oblique intraarticular

fracture of the rim of the distal radius, with

displacement of the carpus along with the

fracture fragment.

Volar Barton‘s Fracture

COLLES‟ VS BARTON‟S

Colles or Smith – Extra-

articular

Barton‘s – Intra-articular

Colles’ Fracture

Barton’s Fracture

In Barton‘s Fracture,

surgical fixation is usually

necessary when over 50%

articular surface is involved

or fragment not adequately

reduced

ROLANDO VS BENNETT‟S FRACTURE

Bennett fracture

Rolando fracture (comminuted;

worse prognosis)

• Because of protection by surrounding

muscles, most radial shaft fractures require

significant force and most have concurrent

ulna fractures

• Also, non-displaced fractures are rare

• In ulna shaft fractures, solitary fracture of

ulna may occur, often called nightstick

fracture since it can be caused when stuck

with a blunt object while self-defencing.

RADIUS AND ULNA SHAFT FRACTURES

MONTEGGIA‟S

FRACTURE

Is a fracture at the junction

of the proximal and middle

thirds of the ulna

associated with anterior

dislocation of the proximal

radial head

GALEAZZI'S FRACTURE Involves the

junction of the

middle and distal

thirds of the

radius, with an

associated

dislocation or

subluxation of the

DRUJ.

Mnemonics: MU-GR

Monteggia = ULNA

Galeazzi = RADIUS

ELBOW X-RAY

ANATOMY OF THE ELBOW

Mnemonic: “CRITOE”

Secondary growth centers of the elbow

OSSIFICATION CENTERS

Ossification Center Age appearing

radiologically

C = Capitellum 1 year old

R = Radial Head 3 years old

I = Internal epicondyle 5 – 7 years old

T = Trochlear 9 – 10 years old

O = Olecranon 9 – 10 years old

E = External epicondyle 9 – 10 years old

Scaletta & Schaider, 2001

ANTERIOR HUMERAL LINE

This line passes

through the

middle one third

of the capitellum

in bones that

are not injured

RADIOCAPITELLAR LINE

If radiocapitellar

line does not

pass through

capitellum, a

dislocated radial

head is

suspected

ANTERIOR AND POSTERIOR FAT PADS

Posterior fat pad

Normally anterior fat pad is seen

only as an anterior narrow strip of

lucency but the posterior fat pad is

not seen as it is hidden in the

olecranon fossa.

Anterior fat pad with

sail sign appearance

(due to joint effusion)

ANTERIOR AND

POSTERIOR FAT PADS

Anterior fat pad displacement in the

lateral view suggests effusion, but if the

posterior fat pad is visible at all, an elbow

fracture is likely.

In the absence of trauma, the presence

of a fat pad suggests other causes of

effusion (e.g., gout, infection, bursitis)

Search hard for occult fractures,

which are:

1. Radial head fracture (in adults)

2. Supracondylar fracture (in children)

Lateral view AP View

Discuss the abnormalities seen

Diagnosis?

SUPRACONDYLAR FRACTURES

• Most frequent elbow fracture in children, accounting

for 50-60% of cases

– Most occur in children aged 3-10 years, with a peak

incidence in those aged 5-8 years

• 10% have radial pulse loss temporarily, most often

as a result of swelling and not direct brachial artery

injury.

• Reducing the fracture, avoiding flexing the elbow

more than 90 degrees, and elevating the arm help

prevent secondary obstruction to arterial flow.

Relative ligamentous

laxity in childhood

allows the elbow to

hyperextend, and with

hyperextension, the

olecranon transmits

the load into a

bending force on the

distal humerus in the

supracondylar region.

10-POINT CHECKLIST IN INTERPRETING

ELBOW X-RAY

• 1. Examine the anterior fat pad

• The presence of an anterior fat pad is normal. It

should be small and appear to be flat against the

anterior surface of the humerus.

• If it is large or it appears to be triangular in shape

(sail shape) as if its lower tip is being displaced

upwards, this indicates the presence of an elbow

joint effusion

• 2. Look for the presence of a posterior fat pad.

• A posterior fat pad is always an abnormal sign and

indicates the presence of an elbow joint effusion

• 3. Examine the anterior humeral line.

• If this line fails to bisect the capitellum, this

indicates the presence of a fracture in the

supracondylar region displacing the capitellum

(usually posteriorly) or a Salter-Harris Type I

fracture between the capitellum and the distal

humerus.

10-POINT CHECKLIST IN INTERPRETING

ELBOW X-RAY

• 4. Examine the radial head

• The shape of the radial head should show a

smooth metaphysis. Any angles in the metaphysis

may indicate a radial head fracture.

• 5. Examine the radiocapitellar line

• The radius should point directly at the capitellum in

all views. If the radius does not point directly at the

capitellum, this indicates a dislocation of the radial

head.

10-POINT CHECKLIST IN INTERPRETING

ELBOW X-RAY

• 6. Count the number of ossification centers

• CRITOE sequence

• 7. Check for the Hourglass sign OR Figure-of-8

shape at the distal humerus to indicate that the X-

ray is a true lateral view

• An oblique view of the elbow may obscure some

radiographic findings

10-POINT CHECKLIST IN INTERPRETING

ELBOW X-RAY

• 8. Look carefully at the distal humerus

• Any lucencies indicating a supracondylar fracture

• 9. Examine the olecranon and the remainder of the

ulna for irregularities in the cortex.

• An ossification center over the olecranon may

resemble a fracture. The presence or absence of

tenderness over the olecranon may help to

establish a diagnosis

• 10. Correlate X-ray with clinical picture

10-POINT CHECKLIST IN INTERPRETING

ELBOW X-RAY

10 THINGS TO LOOK FOR IN ELBOW X-

RAY

1. Anterior fat pad

2. Posterior fat pad

3. Anterior humeral line.

4. Radial head contour.

5. Radiocapitellar line

6. Ossification centers - CRITOE

7. Hourglass sign

8. Distal humerus

9. Ulna/Olecranon

10.Clinical correlation

Checklist:

1. Anterior fat pad.

2. Posterior fat pad.

3. Anterior humeral

line.

4. Radial head

contour.

5. Radiocapitellar line.

6. Ossification

centers. CRITOE

7. Hourglass sign.

8. Distal humerus.

9. Ulna/Olecranon.

10. Clinical

correlation.

ANKLE AND FOOT X-RAY

ANKLE MORTISE VIEW

Check joint space around talus

for symmetry/disruption

Search for fractures of distal

tibia and fibula

The lines formed between the

articular surfaces should be

parallel throughout the

tibiotalar and talofibular

components of the joint

MALLEOLAR FRACTURES

• The stability of an isolated lateral malleolar fracture depends on the location of the fracture in relation to the level of the tibiotalar joint.

• Medial malleolar fractures are commonly associated other fractures/disruption

• Therefore, the identification of a medial malleolar fracture demands a careful examination of the entire length of the fibula for tenderness (Maisonneuve fracture)

MAISONNEUVE FRACTURE

LISFRANC‟S JOINT

Lisfranc‘s Joint - Bases

of the first three

metatarsals with their

respective cuneiforms

and the fourth and fifth

metatarsals with the

cuboid

CALCANEAL INJURIES

Boehler‘s angle of 20 to

40 degrees gives the

best balance of

sensitivity and

specificity for fracture

detection

An angle of less than 20 degrees suggests a

compression fracture of calcaneum