imaging LE - exam 3 Flashcards
what does a hip AP view visualize?
hip joint and proximal femur
what is the iliofemoral line that you can see in a AP view
smooth curve along outer ilium that extends into the neck
what is Shenton’s hip line that you can see in a AP view
smooth curve around obturator foramen
what is the femoral neck angle seen in AP view
aka angle of inclination
angle between femoral shaft and neck
what is observed as normal in hip AP view?
well preserved joint space
smooth margins of acetabulum and femoral head
obvious ball and socket
cortex margins on shaft
cancellous markings on head and neck
what does a hip lateral frog leg view visualize?
head, neck and proximal femur
what is observed as normal in hip lateral frog leg view?
lesser trochanter is more anterior
well preserved joint space
smooth margins of acetabulum and femoral head
obvious ball and socket
what are routine radiographs of the hip?
AP
lateral frog leg
what are routine radiographs of the knee?
AP
lateral
PA axial “tunnel” view
tangential view
what does the knee AP view visualize?
distal femur
proximal tibia and respective joint
fibular head
what are important observations of normal knee in AP view
patella superimposed and not typically visible unless patella baja
well defined joint spaces and equal
alignment of femur and tibia
distinct cortical margins and cancellous markings
what does the knee lateral view visualize
profile of PF joint
what are important observations in knee lateral view?
patellar alta/baja positioning
what does the knee PA axial tunnel view visualize?
intercondylar fossa and eminence
post. femur and tibia
tibial plateaus
used to detect loose bodies, osteochondral defects, or narrowing of tibiofemoral joint space
often performed in standing for ARJC
what is normal observation for knee AP axial tunnel view?
tunnel should be open, round and not squared off
well defined joint spaces and equal
what does the knee tangential view visualize?
PF joint space and surfaces
what is normal observation for knee tangential view?
- sulcus angle
- congruence angle
smooth and distinct surfaces
- sulcus angle, esp depth. if shallow, more prone to dislocations
- congruence angle - helps to define patellar position within the sulcus
congruence angle:
____ deg is associated with patellar hypermobility and dislocations as there is greater medial tilt
> 16 deg
conventional radiographs should be ordered after trauma to the knee for patients with:
age > 55
tenderness at fibular head
isolated tenderness of patella
inability to flx knee to 90
inability to walk four WB steps immediately after injury and in the ED
** can’t be used after 7 days of trauma
what are the routine radiographs for the ankle?
AP
AP oblique (mortise)
lateral
what does the ankle AP view visualize?
distal tibia and fibula and talar dome
what is normal observation of an ankle AP view?
lateral malleolus more distal than medial
visualize upper and medial talus - medial or lateral shift of talus is abnormal
distal tibiofibular joint space - abnormally wide joint is abnormal
what does an ankle AP oblique (mortise view) visualize?
entire ankle mortise with 15-20 deg of hip IR
what is a normal observation of ankle AP oblique view?
entire talocrural joint space
mortise width - 3-4 mm or < 1/2 cm all the way around (normal)
distal tibiofibular joint - NO optimal radiographic parameter exists to assess syndesmotic integrity but > 6 mm is utilized
what does the ankle lateral view visualize?
tibiotalar and subtalar joints
talonavicular and calcaneocuboid joints
bony members
what is the ankle anterior drawer stress view? where do you measure from?
x-ray while performing ligamentous special test
measure from post. tibia to post. talus
values of ankle anterior drawer stress view:
- normal:
- abnormal:
- _____ separation requires comparison between sides
- 5 mm or .5 cm
- > 10 mm or 1 cm
- 5-10 mm
what is the ankle EV/IV stress view? where do you measure from?
x ray while performing ligamentous special test
measure angle between bottom of tibia and talar dome
what are abnormal findings of the ankle EV/IV stress view?
mortise widens
talar displacement or tilt
> 15 deg for IV and > 10 deg for EV
if > 5 deg difference between sides of the body
what are routine radiographs of the foot?
AP
lateral
oblique
foot AP view visualizes:
mid and forefoot
what are important normal observations of the foot AP view?
note individual mid and forefoot bones along with sesamoid bones
1st intermetatarsal angle - intersection of lines bisecting 1st and 2nd MT shafts
(normal < 5-10 deg)
what does the foot lateral view visualize? how is that different from the ankle?
subtalar, talonavicular, and calcaneocuboid joints and members
different from ankle bc less tibiofibular imaged
how do you take a radiograph in the foot oblique view?
foot and leg medially rotated
what does the foot oblique view visualize?
primarily for forefoot
all tarsals except 1st cuneiform and portion of talus
what are normal observations of the foot oblique view?
MTs image with sharp clearly defined cortical borders
sesamoids
2nd-4th distal phalanges difficult to visualize
note joint spaces of intermetatarsal and midtarsal joints
radiographs should be ordered after trauma to the ankle with any of the following characteristics:
pain about the medial or lateral malleolus AND
- tenderness at post. aspect or tip of lateral malleolus OR
- tenderness at post. aspect or tip of medial malleolus OR
- inability to bear weight both immediately and in ED
radiographs should be ordered after trauma to the foot with any of the following characteristics:
pain about the midfoot AND
- tenderness at 5th metatarsal base OR
- tenderness at navicular bone OR
- inability to bear weight both immediately and in ED
how do ultrasound waves construct an image
US waves are absorbed, reflected and diffused differently from varying tissues
two major advantages of ultrasound
offers real time information for superficial soft tissue
higher resolution for superficial tendon, ligament and muscle than MRI
two major disadvantages of ultrasound
inability to scan deeper joint structures
image quality highly dependent on operator
what is hyperechoic appearance
higher (brighter) signal from reflection of smoother and denser structures indicate swelling, tendinosis
sonograph:
- tears:
- swelling, thickening
irregular borders or lack of structure
wider structure
why choose radiographs for LE imaging?
initial images
CT and MRI are recommended for :
complex fractures
osteochondral lesions
MRI recommended for:
stress fxs and tendon abnormalities
MRI arthrography with contrast recommended for:
ligamentous and cartilage issues
ultrasound appropriate for:
superficial soft tissue abnormalities
