Di imaging Exam 4 Chat 2.0

Congenital vs acquired block vertebra — key difference?

Congenital = segmentation failure during development; Acquired = post-trauma, infection, surgery, degeneration.

Disc appearance in acquired fusion?

Obliterated or hazy disc

Anterior vertebral body margins in congenital block vertebra?

Smooth bridging with combined concavity (wasp waist)

Anterior vertebral body margins in acquired fusion?

Flat or squared

Vertebral body height in congenital block vertebra?

Combined vertebral body is taller

Vertebral body height in acquired fusion?

No change in vertebral body height

Foramen size in congenital block vertebra?

Large foramen may be seen on lateral view

Foramen size in acquired fusion?

No change in foramen size

What is Os Terminale?

Failure of union of secondary ossification center at tip of dens

Normal age of appearance of dens secondary ossification center?

3-6 years old

When does Os terminale become pathological?

If present after age 12

Is Os Terminale associated with instability

No

What is LMD

Overhang of C1 lateral masses wider than superior articular facets of C2

Normal C1:C2 lateral mass ratio?

80% = 1:1 ratio

Pathologic C1:C2 ratio?

> 100% OR >1.15

LMD is 100% specific for injury to what structure?

Transverse Atlanto-Axial Ligament

Percentage of TAL injuries showing LMD

90%

Cause of LMD

Fracture of C1 ring or disruption of the transverse ligament.

Type I C1 fracture?

Fracture of the C1 ring

Type II C1 fracture?

BOTH posterior AND anterior arch fracturesfracture involving the odontoid process of C2

Type III C1 fracture

Lateral mass fracture

What determines stability of atlas fractures?

Integrity of the TAL

Types of atlas fractures

Burst (Jefferson), Jefferson-Burst, C1 burst fracture

What is OS odontoideum

Separation of dens from C2 body

Primary causes of Os Odontoideum?

Failure of synchondrosis or prior fracture

Imaging modality best to evaluate dens cortex

CT

Type 1 dens fracture?

Avulsion of tip

Type II dens fracture?

At base of odontoid

Type III dens fracture?

Extends into C2 body

Characteristic C1 anterior tubercle finding?

Rounded posterior border of the anterior tubercle. (molding defect)

Why does the anterior tubercle remodel?

Absence of articulation with C2

Additional C1 finding with os odontoideum

Hypertrophy of anterior tubercle

Effect on spinal canal with os odontoideum

Reduced space due to anterior translation of C1

Can os odontoideum be asymptomatic?

Yes

Possible symptoms with os odontoideum

Neck pain, headache, torticollis

Neurologic symptoms with os odontoideum

UE paresthesia, LE weakness, gait abnormalities

Vascular risks of os odontoideum

VBA occlusion → brainstem ischemia

Motion changes at C1-C2 with os odontoideum

Increased motion

Treatment options for os odontoideum

Observation to surgery

Sports recomendation for os odontoideum

avoid contact sports

Syndromes associated with Os Odontoideum?

Down syndrome, Klippel-Feil, Morquio, Neurofibromatosis

Other associated findings with os odontoideum

Hypoplastic C1 posterior arch

Non-traumatic LMD causes?

Congenital asymmetry, ligament laxity/absence, inflammatory or metabolic arthritisinfection, tumors, or degenerative changes

Slight lateral mass overhang is normal in whom?

Very young children only.

Cause of butterfly vertebra?

Persistent notochordal tissue

Ap appearance of butterfly vertebra

Widened vertebral body with central cleft

Adjacent vertebral adaptation with butterfly vertebra

Endplates invaginate into cleft

Most common locations of butterfly vertebrae

T1 and lumbar spine

Clinical significance of butterfly vertebra

Typically insignificant.

Cause of hemivertebra

Failure of one lateral ossification center

Most common type of hemivertebra

Lateral hemivertebra

Major clinical outcome of hemivertebra

Structural scoliosis

Segmented hemivertebra?

Free moving with discs above and below

Effect of segmented hemivertebra?

Greater scoliosis progression

Non-segmented hemivertebra?

Fused to adjacent vertebrae; decreased motion

Differential diagnosis for hemivertebrae

Compression fracture

Two hemivertebrae on same side causes?

Progressive scoliosis and potential thoracic deformity.

Two hemivertebrae on opposite sides cause

Mild scoliosis

Definition of transitional vertebra?

Incomplete segmentation at transition zones

Sacralization

L5 resembles S1

Lumbarization

S1 resembles L6

Batwing appearance?

Hyperplastic transverse process.

Accessory joint formation may cause?

Degeneration

Thoracic transitional rule?

Look for lumbar ribs

Vertebral count rule?

Cervical is ALWAYS 7

When unsure how do you count?

Normal vertebral count

Clinical significance of transitional vertebrae?

Back pain, disc herniation above, accessory joint OA

What label must be visualized for assessment of number of vertebrae

T1

Definition of facet tropism?

Asymmetric facet orientation

Most common level of facet tropism

L5-S1

Best imaging modality of facet tropism

Ct

Cervical levels with most degeneration?

C2-C3 and C6-C7

Facet tropisms relationship to degeneration

Debatable

TP Accessory articulation cause?

Elongated costal portion of Tp

Best imaging for Accessory articulation

CT

Differential diagnosis for accessory articulation

osteophyte

Clinical significance of accessory articulation

Unknown

Definition of persistent apophysis

Non-union of growth center at tendon/ligament attachment

Best imaging for persistent apophysis

MRI

MRI findings of persistent apophysis

Physeal widening, marrow edema, soft tissue edema

persistent apophysis adult significance

none

Pediatric significance of persistent apophysis

usually minimal

What is Oppenheimer ossicle

non-union of facet joint ossification center

Where is Oppenheimer ossicle located

Inferior articular process, usually L2-L3

Cortication of Oppenheimer ossicle

Well-corticated

Classic sign of absent pedicle

Winking owl sign This sign indicates a missing or poorly developed pedicle on imaging, resembling an owl's appearance.

Congenital compensatory finding of absent pedical

hypertrophy of contralateral pedicle

How to determine chronicity with absent pedicle

prior imaging and time

Significance of hahn vascular cleft

none- normal variant

Most affected hip in hip dysplasia

Left (1/3 bilateral)

Best modality before 6 months with hip dysplasia

Ultrasound

Alpha angle normal?

>60 degrees

Normal femoral head coverage?

>50

Teardrop width normal?

9-11mm or <2mm asymmetry

What is Putt’s Triad?

Small femoral head, lateral displacement, increased acetabular angle

Key line in the Acetabular protrusion

Ilioischial (Kohler’s) line

Diagnostic threshold of acetabular protrusion

>3mm women, >6mm men

Center- edge angle in acetabular protrusion

>40 degrees

Associated diseases mnemonic for Acetabular protrusion

MY PROTRUSION (Marfan, Paget, RA, OI, Trauma, Rickets, Idiopathic, Psoriatic, Inflammatory, Osteomalacia)

Cam deformity sign?

Pistol-grip deformity of the femoral neck associated with hip impingement.