MSK 1 - Radiology Principles Flashcards
what is the criteria to follow for ordering imaging studies?
The American College of Radiology (ACR) Appropriateness Criteria
what is the initial imaging study of choice following skeletal trauma?
X-ray
what 4 things does X-ray evaluate?
- cortical integrity
- articular surface congruity
- joint space
- osseous lesions
how many views to get for X-ray? what are they?
at least 2 views - AP/Lateral
if pt has extremity pain with negative x-ray, but still have high suspicion of fracture, what do you do?
treat as fracture and splint
have pt follow-up with ortho in 7-10 days
repeat x-rays may show cortical changes
important patient info for x-ray interpretation?
patients name, gender, and DOB
CT scan used to identify?
use in trauma to identify and characterize injury pattern/severity
how is CT better than X-ray?
CT better than X-ray in:
- identifying subtle fractures
- visualizing articular extension of fracture
- assessing for the presence of articular step-off/gap
when is MRI used?
primarily for soft tissue evaluation
diagnosing occult (hidden) fractures (ex: femoral neck fx)
dx ligament or articular cartilage injury
for what is MRI the modality of choice?
disc herniation (get X-ray first)
to assess “internal derangement” of joints - ex: ACL tear
when is U/S used?
used in trauma setting to assess soft tissue injury
examples of using U/S?
Achille’s tendon rupture and quad tendon rupture
bone scan used when?
mets, stress fractures
what is a comminuted fracture?
> 2 fracture fragments
what is the least common type of fracture?
spiral factures
spiral fractures are inherently ___
unstable
what is a butterfly fracture?
subtype of comminuted fx with wedge-shaped fracture fragment along shaft of bone
what should be described for fractures?
location and any displacement of fracture fragments
most fractures appear as what line?
radiolucent line
in non displaced fox’s, Lucent line is what?
thin and may be difficult to appreciate
what do mach bands represent?
optical illusion - due to 2 superimposed objects
where do mach bands appear?
at sites of cortex overlap b/w two bones, or skin fold overlap of the cortex
mach bands most common at what site?
ankle radiographs (tibia overlaps fibula)
what type of fracture may appear as a sclerotic line?
compression fractures
most common locations of sclerotic fracture line?
vertebral bodies and distal radius
what is cortical buckling?
buckling in absence of fracture line
where is cortical buckling seen?
distal radius - most often
intra-articular extension may involve?
articular cartilage only (chondral fx)
both the bone and articular cartilage (osteochondral fx)
what is a chondral fx?
fx involving articular cartilage only
what is an osteochondral fx?
both the bone and articular cartilage are involved
what are the 3 aspects of displacement?
translation (displacement)
angulation
rotation
what is translation?
line drawn down center of bone not continuous at the fracture site
how do you describe translation?
direction of translation of the distal fracture component compared to proximal
the amount of translation (as %age of bone width)
what is displacement?
loss of normal anatomic position
how is displacement graded?
in terms of shaft width in quartiles (25%, 50%)
direction of displacement is described using how many views?
two orthogonal views
what 2 views describe displacement?
AP view shows medial to lateral displacement
lateral view shows anterior to posterior displacement
what does AP view for displacement?
shows medial to lateral displacement
what does lateral view show for displacement?
shows anterior to posterior displacement
displacement is described in terms of?
position of distal fragment compared to proximal
describe what for angulation?
direction of angulation of distal fracture component as compared to proximal
amount of angulation in degrees (estimate)
how many views used to describe angulation?
2 orthogonal views
what is rotation?
turning of the distal fracture fragment in relation to proximal portion
why is rotation important to correct?
b/c anatomic alignment of bone is cortical to normal function
when is rotation seen most easily?
when looking at orientation of joints above and below fracture
what is distraction?
fracture separated by a gap with no overlap
distraction with common with what fractures?
transverse fractures that result from a tension force
what are examples of tension force fractures?
medial malleolar and patella fx
how is an avulsion caused?
by abnormal tensile stress on ligaments or tendons
where in hands do avulsions occur?
dorsal distal phalanx with extensor tendon avulsion
where in feet do avulsions occur?
base of fifth metatarsal with peroneus braves avulsion
where in pelvis do avulsions occur?
ischial tuberosity with hamstring tendon avulsion
at what locations do avulsions typically occur?
hands, feet, pelvis
what can help identify an underlying fracture? when is this very helpful?
soft tissue swelling
-helpful when assessing trauma to the metacarpals or phalanges
what can joint effusions be?
blood or inflammatory fluid (or both)
joint effusion in acute setting in pt with NO arthritis, is a sign of what?
hemarthrosis
what may hemarthrosis be a result of?
of an intra-articular injury to either the soft tissues or adjacent bone
what is a transverse fracture?
fx perpendicular to long axis of bone
transverse fx caused by?
direct force (also tension force)
transverse fx most common where?
in forearm/leg
transverse fx is stable or unstable?
stable
what is oblique fracture caused by?
indirect force
-compression and angulation forces combine to cause shear force
oblique fx is stable or unstable? repaired where?
unstable
repaired in the OR
how are spiral fx’s caused? result from?
by twisting movement thru the long bone axis
result from rotation/shear forces
spiral fx are stable or unstable? repaired where?
unstable
repaired in the OR
what type of fx is the LEAST common?
spiral fx
severity of comminuted fx’s graded as?
minimal or moderate-severe
butterfly fx’s are caused by what force?
indirect force
what do butterfly fx’s produce?
a bending of bone
butterfly fragment produced alone what side?
concave, compression side
what is a greenstick fracture?
incomplete fracture of long bone produced on convex cortex, while concave cortex becomes bent
WITHOUT visible crack
in who and where do greenstick fx’s occur?
in forearm of young child
what does greenstick fx result from?
bending force applied perpendicular to shaft
what is a torus fracture?
a buckle fx
buckle fx is a type of what fx?
incomplete fx
where do buckle (torus fx’s) occur?
at metaphysical diaphysial junction after FOOSH
buckle fractures common after?
after FOOSH
buckle fx stable or unstable?
stable
what are the suggested x-rays for elbow?
AP, external oblique, lateral
what are suggested x-rays for fingers?
AP, oblique of hand, lateral of affected finger
what are suggested x-rays for hand?
AP, oblique, lateral
what are suggested x-rays for thumb?
AP, oblique, lateral
what are suggested x-rays for wrist?
AP, oblique, lateral
what are suggested x-rays for hip?
AP pelvis, frog lateral
what are suggested x-rays for ankle?
AP, mortise, lateral
what are suggested x-rays for femur?
AP, lateral
what are suggested x-rays for foot?
AP, oblique, lateral
what are suggested x-rays for knee if under 40 y/o?
AP, lateral, tunnel, sunrise
what are suggested x-rays for knee if over 40 y/o?
bilateral PA weight bearing (aka 30 degrees PA flex view)
bilateral tunnel, bilateral sunrise, lateral of affected knee
what are suggested x-rays for tib-fib?
AP, lateral
what are suggested x-rays for heel?
axial, lateral calcaneus
what are suggested x-rays for AC joint?
AP with and without weights
what are suggested x-rays for chest?
PA, lateral (full inspiration)
what are suggested x-rays for clavicle?
AP, axial (20 degree caphalad)
what are suggested x-rays for humerus?
AP, lateral
what are suggested x-rays for ribs?
AP, obliques (bilateral)
Upper: inspiration
Lower: expiration
what are suggested x-rays for SC joint?
AP, obliques (bilat)
what are suggested x-rays for shoulder?
AP, Grashey, Y-scapular view
