Practical 2: MSK XRs Flashcards
Who do greenstick fractures occur in?
children
What might you see in long bones of children on XR?
growth plates visible
How do you describe XRs in terms of brightness?
Radiolucent and radio-opaque
What are the standard views for the C spine?
AP, Lateral and Peg (open mouth)
Why might you request a swimmer’s view in someone?
To assess the C7/T1 junction that may not be visible on lateral view
What 3 lines do you look at on lateral C spine view?
Anterior vertebral line*
posterior vertebral line*
spinolaminar line
*correspond to the longitudinal ligaments
What 3 columns might the C-spine might be described as? If one of these columns is disrupted what does this indicate?
Anterior (ant long. ligament –> ant 1/2 vertebral body)
middle (post. 1/2 vertebral body –> post. long. lig)
posterior (posterior elements of vertebra)
indicates instability
What is special about the role of the anterior longitudinal ligament?
Only ligament to Prevents hyperextension of the spine
others resist hyperflexion
Where do the posterior and anterior longitudinal ligaments run from and to?
posterior: C2 (posterior to body) –> sacrum [n.b. runs w/in the vertebral canal w/ the spinal cord]
anterior: occipital bone base –> sacrum
both are posterior or anterior to the vertebral body
What soft tissue spaces should you look at on a lateral c spine view?
nasopharyngeal
Retropharyngeal
retrotracheal
What would you do if one of the soft tissue spaces on the lateral C spine is >7mm above C5 or > than the width of one vertebral body below C5?
Suggests fracture –> CT scan
What should you look for on a Peg view?
the spaces between the C1 lateral masses and C2 peg/dens should be equidistant and small
what lies anterior to the dens? Why is it important?
The transverse ligament of C1/atlas. Prevents dens fracture affecting the spinal cord
what type of joint is between the dens and C1 anterior arch?
Synovial (therefore affected in RA pts)
is the dens anterior or posterior?
ANterior (don’t get confused by pics)
What is special about the vertebral foramen of the C vertebra?
Wide therefore subluxation may not compress the spinal cord
How are the superior and inferior articular facets of the C vertebra directed?
Superior: supero-posteriorly
inferior: infero-anteriorly
What is special about the spinous processes of the C vertebra?
Bifid
What is a clay shoveler fracture? Why is it called this?
Who can it be seen in acutely?
Fracture of the spinous process (lower c-spine [usually c7])
Clay is sticky –> as you shovel upwards there is a sudden flexion force
Acutely: motor vehicle accident, sudden onset muscle contraction (clay), direct blows to the spine
Are clay shoveler fracture injuries recognised at the time?
No, picked up incidentally when imaging C spine for ther reasons
What is an extension teardrop fracture?
Associated w/ whiplash / read end collision
hyperextesnion of the neck causes the anterior longitudinal ligament to be torn –> fracture of the vertebral body
in severe cases: a vertebral body dislocates posteriorly + compresses spinal cord
(n.b. you can get a flexion teardrop fracture)
What does the ligamentum flavum do?
Binds the lamina of the adjacent vertebrae
What is the special role of the posterior longitudinal ligament (other than preventing hyperflexion)?
prevents posterior disc herniation (protecting the spinal cord)
What does unequal distance of the C1 lateral masses from the peg/dens suggest?
Fracture of the C1 ring
can be equal distance but large also suggesting fracture
What is a hangman fracture? What is interesting about its aetiology?
fracture of C2’s pars interarticularis (bilaterally) due to high-velocity hyperextension injury
Never seen in hangings –> more associated w/ high speed motor vehicle accidents
What might be at risk in a Hangman fracture? How?
Vertebral artery if the fracture extends to the transverse foramina
Where does the pars interarticularis lie?
between the superior and inferior articular processes of the facet joints
What is a Jefferson fracture? What is it caused by? What should you request?
C1 burst fracture (fracture of both posterior and anterior arches) due to axial load to head (e.g. diving)
CT!!!
What is an oblique view of the T/L spine good for?
Shows you the scotty dog appearance –> useful in examination of pars interarticularis
what do the spinal nerves come out of?
The intervertebral foramen
How does the rib articulate with the T vertebra?
The transverse process has a costal facet for tubercle of the rib
The vertebral body has sup/inf costal facet for head of the rib
What might you see in a lateral T/L spine view in someone older?
Calcification of the aorta
concave vertebral bodies
What 3 lines make up the y view in a shoulder?
coracoid, acromion, scapula blade/body
how is the patient positioned in a XR Y view of the shoulder?
arm extende
how is the patient positioned in a XR axial of the shoulder?
arm abducted
Why do a Y view of the shoulder?
differentiate ant. from post. humeral head dislocations
Why do an axial view of the shouldeR?
dislocations, visualisation of the humeral head + glenoid fossa
What is a supracondylar fracture? Who is it seen in?
Fracture of the distal humerus
Children/young teens
What structures are at risk in a suracondylar fracture?
Median nerve and brachial artery
What is the mechanism of injury for posterior elbow dislocation? What structure is at risk?
Fall onto flexed elbow, hyperextension (causes posterior displacement of ulnar)
ULNAR NERVE
What are the scaphoid views?
PA, PA w/ ulnar deviation, oblique and lateral
What is the use of a lateral view of the wrist?
sees if capitate, lunate and radius are in line –> may show luneate dislocation
What is a boxer’s fracture?
Punch –> fracture of distal/neck of 4th and/or 5th MCs
What are the 4 types of intracapsular fractures? What is at risk?
head of femur
subcapital
transcervical
basicervical (can be extracapsular)
Middle circumflex artery (from deep femoral a.) supplying proximal femur
What are the 3 types of NOF fractures?
subcapital
transcervical
basicervical
What are the (3) types of extracapsular fractures
basicervical (can be intracapsular too)
trochanteric
subtrochanteric
How will the leg look in a NOF#?
Short and externally rotated
how do you classify NOF#s?
Garden classification system
What is special about garden II fractures?
The trabecular lines are normal (interrupted in I, III and IV)
What is there a Hx of in Lisfranc fracture-dislocation? What may you need to request?
Midfoot trauma
request CT (XR may be equivocal)
On a C spine lateral view, what should the widths be of the soft tissue spaces? What if they’re greater than this?
<7mm above C5
< width 1 vertebral body below C5
If greater –> CT
What are the pedicle + lamina of vertebra?
Lamina connects the transverse process w/ the spinous process (ligamentum flavum connects lamina of adjacent vertebrae)
Pedicle connects the vertebral body w/ the transverse process
What is at risk of a posterior elbow dislocation?
Ulnar nerve
Why are elbow dislocations rare? What do they most usually occur from?
Elbow joint one of the most stable joints
sports activities (50%)
