Lecture 3-Lower Extremity Flashcards
What joint spaces should be open in an AP axial foot?
-TMT
-Medial and Intermediate cuneiforms
-Navicular-cuneiforms
Where should the talus be located in relation to the calcanus for an AP axial foot?
Talus superimposes slightly the most distal part of the calcaneus
What is the best way to obtain a proper angle for an AP axial foot?
The best way to obtain the proper angle is to go perpendicular to the dorsal plane of the foot
Which bone to we hit first in an AP axial of the foot; the talus or calcanus?
Talus
What corrective measures should be taken to correct this image of the AP axial foot?
Rotate the foot internally, increase the angle to see through the joint spaces
What error(s) have been made in this image of the AP axial foot?
-Foot is too internally rotated
-Talus and calcaneus is clipped
What corrective measure(s) should be made for this image of the AP axial foot?
Need more of a cephalad angle to see joint spaces
What joint spaces/spaces should be seen in an oblique foot?
-Cuboid-lateral cuneiform
-3rd – 5th proximal MT
-Sinus tarsi
-2nd – 5th intermetatarsal spaces
How can you demonstrate the subtalor joint in an AP oblique foot?
Dorsiflex the foot 90 degrees
What structure is circled?
The subtalor joint
What errors have been made to this image of the AP oblique foot?
Under obliqued, Cannot see the subtalar joint space, clipping the talus
What error(s) have been made in this image of the AP oblique foot?
-Clipping anatomy, out marker on the lateral side, over rotated-lost the space between phalangies
What pathology is visualized in this image?
Tarsal coillition and Dancers fracture
What error(s) have been made in this image of the AP oblique foot?
None; perfect positioning
Where should the talar domes be in a lateral foot projection
Talar domes superimposed on eachother
What joint should be visualized in a lateral foot projection?
Subtalor joint visualized
T/F
In a lateral foot, the metatarsals should be superimposed
False; not superimposed
Where should the fibula be in a lateral foot projection?
Fibula superimposed in the posterior 1/2 of the tibia
What correction needs to made for this image? How can you tell?
-Foot needs to be lined up on the lateral aspect
(fibula too posterior)
T/F
If calcification in the vessels of the foot, the patient is possibility diabetic
True
What error(s) have been made in this image of the lateral foot?
Knee raised off the table, not dorsi flexed
What joint spaces should be open for an AP ankle?
-Tibiotalar joint space
-Medial mortise
T/F
In an AP ankle, the distal fibula overlaps lateral talus
True
What error(s) have been made in this image of the AP ankle? How do we know?
-Foot externally rotated (Fibula and talus are overlapping too much)
What error(s) have been made in this image of the AP ankle?
Foot is internally rotated
Why do patients ussually require an angle for the mediolateral ankle?
The ankle is lower than the knee naturally causing tilt
Does this patient require an angle for the mediolateral ankle? How much?
10-12 degrees
What joint spaces should be seen in an ankle mortise?
3 equal joint spaces around mortise
What is the most important ankle image for surgeons?
The ankle mortise
If the patient is unable to dorsiflex the foot in an ankle mortise, what should we do?
Angle cephalad
T/F
In an ankle mortise, the fibula should 1/2 superimposed with tthe talus.
False; Distal fibula demonstrated without superimposition
What error(s) have been made in this image of the ankle mortise? How do we know?
Have not internally rotated enough because we cannot see joint space
What error(s) have been made in this image of the ankle mortise? How do we know?
Not internally rotated enough (medial joint space not open enough)
What corrective measure(s) need to be made for this image of the ankle mortise?
Needs more internal rotation
How many mm distally should the tib and fib be apart?
Have to have at least two mm between tib and fib distally
What error(s) have been made in this image of the Ankle mortise? How do we know?
Too much internal rotation (When you see the O, (sinus tarsi) the ankle has been over rotated )
What correction(s) need to be made to this image of the Ankle mortise?
-Cephlad angle needs to be used or the patient needs to dorsiflex the foot
What joint spaces need to be open in a lateral ankle?
-Tibiotalar joint space
-Subtalar joint
T/F
In a lateral ankle, the talar domes need to be superimposed.
True
Where should the fibula be in a lateral ankle radiograph?
Fibula in posterior half of tibia
What angle is ussually required for a mediolateral ankle?
5 degrees cephalad
T/F
The position of the talar domes in a lateral ankle depends on the location of the calcaneus and the toes
True
What correction should be made to fix this lateral ankle?
A cephalad angle is needed (or lower the knee) and the toes need to go down or the calcaneus up off the IR. Also, align the tibia with the long axis of the IR
What corrections need to be made to this image of the lateral ankle?
Bring the toes down and use a cephalad angle
What structure is circled?
Sustentaculum tali
What error has been made in this image of the lateral ankle?
The knee was raised off the table or not enough of a cephalad angle was used. Additionally, the toes were raised off the table or IR.
T/F
There is no angle needed for a standing lateral
True
How could the talar domes become even more superimposed
The marker should have been placed face down and then the image flipped!!! The heel was not moved away from the IR.
What is the error?
The fibula is too posterior, and the sinus tarsi and the subtalar joint is visible in a medio-lateral ankle projection.
The heel is raised off the IR
What is the error?
The fibula is too anterior and the subtalar joint is visible in the lateral ankle projection.
The toes are off the IR
Sinus tarsi is NOT visible
What angle; caudad or cephalad, would be used? Why?
Talus is going opposite angle so we need a caudad
What angle would you use for a mediolateral projection?
7-10 degree angle needed
In an AP knee, where should the pattella be located?
Patella is slightly lateral to the midline
In an AP knee, where should the fibia be in relation to the tibia?
-Lateral condyle of tibia superimposes half of fibular head
-Fibula also roughly half way between the articulating surface of the tibia and the curved part of the metaphysis
(up and down, left and right)
What errors have been made in this image?
-Foot too externally rotated
-Fibular head appears too superior; used too much of a caudad angle
What caused the joint space not to be visualized?
The tech centered to superiorly
What error was made in this iamge of the AP knee?
Not angled enough caudad (fibular head too low)
What error was made in this image of the AP knee?
Knee too externally rotated
What errors have been made in this image of the AP knee?
-Knee too internally rotated
-Not enough caudad angle used
What joint space needs to be open in an Internal (Medial) Oblique Knee?
-Proximal tib/fib joint is open
What projection of the knee is best for assessing proximal tib/fib joint, fibular head/neck fractures, and tibial plateau fractures?
Internal (Medial) Oblique Knee
Where should the patella be visualized in an Internal (Medial) Oblique Knee
½ of the patella is visualized medial to the femur
What projection is this?
Internal (Medial) Oblique Knee
What error has been made in this image of the Internal (Medial) Oblique Knee?
(left knee done PA)
Knee over rotated;looks closer to a lateral
Where should the fibular head be located in an External (Lateral) Oblique Knee?
Fibular head is aligned with the anterior edge of the tibia
(fibula in the middle of the tibia is what John likes better)
Where should the patella be located in an External (Lateral) Oblique Knee?
Approximately ½ of the patella is visualized lateral to the femur
What is the best projection for assessing tibial plateau fractures?
External (Lateral) Oblique Knee
What are the differences between the medial and lateral condyles of the femur?
-Medial condyle has roughened area – adductor tubercle
-Lateral condyle is smooth
How much should the knee be bent in a lateral knee projection?
30 degree bend
What is the difference between the medial and lateral tibial plateuas of the tibia?
-Medial tibial plateau is curved
-Lateral tibial plateau is straight
What happens if you cannot tell if the condyle is smooth or rough and you can’t see the tibial plateus in the lateral knee?
Look at the height of the fibula on the AP projection
In a mediolateral knee, how do you acess for rotation?
By looking at the tibial plateaus
What corrections need to be made to this image of the mediolateral knee?
Need to Externally rotate, and increase the cephalad angle used
What correction needs to be made to this image of the mediolateral knee?
-Need internal rotation, decrease the cephalad angle
What correction needs to be made to this image of the mediolateral knee?
Increase the cephalad angle, externally rotate
What correction needs to be made to this image of the mediolateral knee?
Need to use more of a cephalad angle
What correction needs to be made to this image of the mediolateral knee?
Need to externally rotate the knee and decrease the cephalad angle used
What correction needs to be made to this image of the mediolateral knee?
Less cephalad angle needed
What correction needs to be made for this image of the lateromedial knee?
Need more of a caudad angle and internal rotation
What correction needs to be made to this image of the lateromedial knee?
Decrease the caudad angle, externally rotate the knee
(opp rules to a mediolateral)
Fibular head too distal therefore the lateral femoral condyle too distal
What correction needs to be made to this image of the lateromedial knee?
Decrease the caudad angle
What projection is best to image OA?
PA Standing tunnel is best for OA
What angle is used for a standing PA tunnel view?
Normally 10 degrees caudad
what angle is used for a standing AP tunnel
5 degrees caudad
T/F
What projection is best for imaging loose bodies, assessing tibial plateau fractures, OCD, Chondrocalcinosis
Tunnel views (specifically recumbent)
T/F
In standing tunnel views, steeper slopes need less than 10 degrees and lesser slopes need at least 15 degrees
True
What error has been made in this image?
Too much of a caudad angle used
What projection is this?
Standing AP Tunnel
What projection is this?
Standing Tunnel PA
How much should the knee be bent for a skyline view?
No more than 30°
What indicates proper positioning of a skyline patella view?
- Need to visualize the depth of the trochlear groove at the origin
- Width of the patella should be equal to the femur
- Spike on the medial aspect of the knee
What error has been made in this image of the patella?
None; just a patient with arthitis
What error has been made in this image? How do we know?
Bent less than 30 because of the shallow groove
What is the yellow line indicating?
The trochlear groove
T/F
In a skyline projection, the more you bend the knee, the more distal/closer to the knee the patella goes
True
What error has been made in this image?
Knee has been bent more than 30 degrees (femur wider than patella)
What error has been made in this image?
Knee has been bent more than 30 degrees
What angle would you use for this patient; straight ray, caudad or cephalad?
Caudad
What errors have been made in this image of the AP knee?
-Internally rotated
-Not enough caudad angle
What error has been made in this image of the AP knee?
-Too externally rotated
Where should the greater and lesser trochanters appear in an AP pelvis?
-Lesser trochanters superimposed posteriorly
-Greater trochanters in profile laterally
What should the ischial spines be aligned with in an AP pelvis?
Ischial spines are aligned with pelvic brim
What 4 things indicate RPO positioning of the pelvis?
- Symphysis is to the right of the coccyx
- Left obturator foramen is bigger compared to the right
- Right ilium is wider or more parallel to IR and left ilium is more in profile
- Right ischial spine visualized more than left
What projection of the pelvis is this?
LPO
What error has been made in this image of the AP pelvis?
Legs not internally rotated
What rotation of the pelvis is shown?
LPO
What projection is shown? List at least 6 reasons to justify your answer.
(7 listed, try to name as many as you can)
RPO
1. Left obturator is more open
2. Lesser trochanter more on the right side
3. Right femoral neck more foreshortened
4. Right illum is flatter
5. Ischial spine more visible on the right side
6. Left SI joint is better in RPO position
7. Spinous process appears more to the left of the pedicles
T/F
In an axiolateral hip, the ischial tuberosity should be demonstrated free of superimposition from the greater trochanter
True
Where should the lesser trochanter be in an axiolateral hip?
Lesser trochanter in profile posteriorly
WILL SEE THIS ON CAMRT
On a XTL hip of a suspect # the greater trochanter appeared post to femoral neck, the lesser trochater was superimposed on the femoral neck. What do you do?
Do nothing and send it to packs
What correction should be made to this projection of the axiolateral hip?
Need to decrease the angle between the central ray and the side of the femur
The yellow dotted line indicates the angle used to acquire the image on then previous slide. The solid red line indicates the proper position of the CR.
What correction needs to be made to this projection of the axiolateral hip?
Need to internally rotate the leg
