Ankle and lower leg
from the supine position, how many degrees should the lower limb and foot be rotated to position the ankle for the ap oblique projection for the Mortise joint?
15 - 20 degrees
how many degrees and in what direction should the leg and foot be rotated for the ap oblique projection of the ankle?
45 degrees medially
how do images indicate that a patient has torn a ligament affecting the ankle in the ap stress studies?
an increase in joint space on the side of injury indicates a torn ligament
T/F. an image of the lateral (mediolateral) projection of the ankle should demonstrate the lateral malleolus free from superimposition by the talus.
false
T/F. the ap projection of the leg should demonstrate the fibula without any overlapping with the tibia.
false - proximal and distal articulations of the tibia and fibula should have moderate overlapping
T/F. the ap projection of the ankle should demonstrate the distal third of the fibula without superimposition with the talus
false - some overlap is expected
how can the patient hold the foot in the stress position during ap stress studies?
patient may be instructed to pull on a strip of bandage that is looped around the foot
what procedure should the radiographer perform of the patient is unable to turn from the supine position toward the affected side to position a fractured leg on the IR for the lateral projection?
perform a cross-table lateral projection by placing an IR vertically between the patient's legs
what should the radiographer do if the leg is to long to demonstrate the knee and ankle joint with the same exposure while positioning for the leg?
perform two ap projections to ensure that the entire lower limb is demonstrated
for the lateral projection of the leg, should the patella be positioned perpendicular or parallel with reference to the plane of the IR?
perpendicular
lateral leg (tib/fib) - mediolateral
position - lateral side of leg on IR, femoral condyles perpendicular to IR IR - centered to mid leg CR - enters at mid leg shown / eval - ankle and knee joints, true lateral shown by distal fibula over posterior half of tibia. slight overlap of tibia on proximal fibluar head. moderated separation of tib/fib bodies. possibly no superimposition on condyles because of beam divergence
ap oblique ankle - medial rotation
position - pt supine, dorsiflex foot 90 degrees, rotate medially 45 degrees IR - centered to ankle CR - enters midway between malleoli shown / eval - distal tib/fib, some superimposition over talus, tib/fib joint open, distal tibia and fibula overlap some of talus
ap ankle
position - supine or seated, anatomic position, dorsiflex foot IR - centered to ankle CR - enters ankle at midline of ankle between malleoli shown / eval - ankle centered, medial and lateral malleolus, talus with proper brightness, no rotation shown by normal overlap of the tib/fib articulation with anterior tubercle superimposition over fibula. talus slightly overlapping distal fibula. no overlapping of medial talomalleolar joint. tibiotalar joint space
mortise ankle ap oblique - medial rotation
position - supine or seated, rotate foot 15 - 20 degrees IR - centered to ankle joint CR - enters midway between malleoli shown / eval - entire ankle, mortise joint centered, distal tibia, fibula, and talus. open talofibular joint. open tibiotalar joint, no overlap of anterior tubercle of tibia
ap leg (tib/fib)
position - supine, femoral condyles parallel with IR IR - centered to mid tibia CR - enters mid tibia shown / eval - ankle and knee joints, no rotation shown by proximal and distal articulation of tib/fib moderately overlapped. fibular mid shaft free of tibia superimposition
lateral ankle
position - supine, leg rotated with lateral side down, dorsiflex foot IR - centered to joint CR - enters at medial malleolus shown / eval - distal tib/fib, talus, calcaneus and adjacent tarsals. tibiotalar joint well visualized, medial and lateral talar domes superimposed. fibula over posterior half of tibia. 5th metatarsal base and tuberosity should be seen (this is especially noted for jones fracture) can see outline of distal fibula
what structures and articulations should be demonstrated in the image of the AP oblique ankle?
talus, distal tibia, distal fibula, tibiotalar articulation, talofibular articulation
with reference to the position of the patient's leg and foot during the procedure, how is it determined that the leg has been rotated the correct number of degrees for the ap oblique projection of the ankle?
the intermalleolar plane should be parallel with the IR
if a radiographer positions the lower limb very carefully to ensure that the femoral condyles are physically superimposed, but they do not appear to be well superimposed on the image, what could have caused the image to appear that way?
the natural divergence of the beam may prevent the femoral condyles from appearing superimposed
why is dorsiflexion of the foot required for the lateral (mediolateral) projection of the ankle?
to prevent lateral rotation of the ankle
what is the purpose of performing the AP stress studies of the ankle?
to verify the presence of a ligament tear
T/F. the ap projection of the ankle should demonstrate lateral and medial malleoli.
true
T/F. the ap projection of the ankle should demonstrate the joint space between the medial malleolus and the talus without any overlapping of structures
true
T/F. the foot should be plantar flexed to place the long axis of the foot parallel with the IR in the ap oblique projection of the ankle.
true
T/F. the lateral (mediolateral) projection of the ankle should demonstrate the fibula over the posterior half of the tibia.
true
T/F. the lateral projection of the lower leg should demonstrate some interosseous space between the shafts of the fibula and tiba.
true
T/F. the talofibular joint space should be demonstrated in profile without any bony superimposition in the ap oblique projection of the ankle
true
T/F. the tuberosity and base of the fifth metatarsal should be demonstrated as a lateral projection image of the ankle.
true
