Workbook Chapter 6 Knee: Image Analysis
Accurate CR centering on an AP Knee projection is accomplished by centering the CR (A)_________ inches (B)_________ to the palpable (C)______________.
A) 1 B) distal C) medial epicondyle
Accurate CR Centering on a lateral knee projection is accomplished by centering the CR to the midline of the knee at a level (A)_________ inches (B)____________ to the palpable (C)________________.
A) 1 B) distal C) medial epicondyle
Settegast method: the femoral conyles are at the same height, the patellofemoral joint space is closed, and the anterior tibia is at a distance greater than 0.125 inch distal from intercondylar sulcus.
insufficient CR angulation
On lateral knee projection, the anterior and posterior aspects of the femoral condyles are demonstrated without superimposition. The medial condyle is demonstrated anteriorly. How is the patient mispositioned?
the patella was situated too close to the IR (leg externally rotated)
On an AP axial knee projection, the medial and lateral aspects of the intercondylar fossa are not superimposed, the medial femoral condyle is larger than the medial condyle, and the fibular head demonstrates increased tibial superimposition. How is the patient mispositioned?
the patients leg was externally rotated
On a merchant tangential patellae projection, the patellae are resting against the inercondylar sulci, obscuring the patellofemoral joint spaces. How is the patient mispositioned?
the posterior curve was positioned at or below the bend of the axial viewer.
On a merchant tangential patellae projection, the tibial tuberosities are demonstrated within the patellofemoral joint spaces. The patients calves were not large. How is the patient mispositioned?
the posterior knee curve was positioned too far above the bend of the axial viewer.
Why can joint effusion diagnosis be made when evaluating a lateral knee projection if the knee is flexed less than 20 degrees but becomes difficult to make when the knee is flexed more than 20 degrees?
when the knee is flexed more than 20 degrees, the muscles and tendons tighten, forcing the patella to come in contact with the patellar surface of the femur and obscuring the fat pads.
On a lateral knee projection, the distal articulating surfaces of the femoral condyles are demonstrated without superimposition. The condyle that has the flattest distal surface is demonstrated approximately 0.5 inch distal to the other condyle. How is the patient mispositioned?
The CR was angle too cephalically
Which anatomic structures are included on an oblique knee projection with accurate positioning?
1/4 of the the distal femur and proximal lower leg and surrounding soft tissue
A grid is used for a knee projection if the patient's knee measures more than ________ cm.
10
What is the average CR angle for tangential knee projection (Settegast method)?
10-15 degrees with the lower leg.
What is the sum of the CR angle and the angle of the axial viewer for all tangential knee projections?
105 degrees
What CR angulation is used when obtaining an AP Knee projection in a patient with a large (24 cm) ASIS-to-image table measurement? A)_______________ When imaging a patient with a small (18 cm) ASIS-to-image table measurement? B)__________________
A) 5 degrees cephalic B) 5 degrees caudal
To obtain superimposited distal femoral condylar surfaces when imaging the average patient for a lateral knee projection an (A) ______-degree cephalic CR angulation is used to shift the (B)_________ condyle anteriorly and proximally. The CR angulation is (C)__________(increased/decreased) when imaging a patient with a narrow pelvis and long femora.
A) 5 to 7 B) medial C) reduced
For an open knee joint space and demonstration of the intercondylar eminence and tubercles in profile, the (A)___________ and (B)______________ must be aligned parallel with each other on an AP axial knee.
A) CR B) tibial plateau
How are the CR and the patient positioned to obtain a AP projection that demonstrated the proximal surfaces of the intercondylar fossa in profile? A) CR:_____________ B) Patient:_______________
A) CR aligned parallel with tibial plateau. B) femur position at a 60 degree angle with the imaging table
Accurate CR centering on an AP axial projection is accomplished by first positioning the CR (A)_______ with the anterior lower leg surface; then (B)______ the obtained angulation by 5 degrees and centering the CR 1 inch distal to the (C)__________.
A) Perpendicular B) decreasing C) medial femoral condyle
Lateral Knee: Contrast and density are adequate to demonstrated the (A)___________ fat pad. The patella is situated (B)____________ to the patellar surface of the femur and the patellofemoral joint is open. The distal articulating surface od the medial and lateral (C)______ are aligned, and the tibia superimposes 1/2 of the (D)________________. The (E)_______________ is at the center of the exposure field.
A) Suprapatellar B) proximal C) femoral condyles D) fibular head E) knee joint
How are the femur and foot positioned to demostrate superimposed medial and lateral intercondylar fossa surface on a PA axial knee projection> A) Femur:__________ B) Foot:______________
A) allow the femur to incline medially approximately 10 to 15 degrees B) Position the long axis of the foot perpendicular to the imaging table.
What degree of CR angulation is used for a laterally rotated AP oblique knee projection on a patient whose ASIS-to-image table measurement is 12 cm? A)______________ Why is it common to need a cephalic and for the medially (internally) AP oblique knee projection? B)____________ Why is it common to need a caudal angle for the lateral (externally) AP oblique knee projection? C)____________
A) angle 5 degree caudally B) The hip is often elevated to accomplish the degree of needed internal obliquity C) the hip is placed closer to the imaging table to obtain the needed external obliquity.
How is the positioning setup for a tangential knee projection adjusted when imaging a patient with large posterior calves? A)_______________ If this positioning setup is not changed, what anatomic misalignment appears on the resulting projeciton? B)________________
A) decrease the angulation set on the axial viewer B) the tibial tuberosities will be demonstrated within the patellofemoral joint spaces.
Which anatomic structures are included on an AP axial knee projection with accurate position?
Distal femur, proximal tibia, and intercondylar fossa, eminences, and tubercles.
If the knee is rotated from an AP projection, will the femoral condyle positioned closer to or father away from the IR appear larger on the resulting projection?
Farther away
Inferiosuperior: the lateral femoral condyle demonstrates more height than the medial condyle, the patellofemoral joint space is closed, and the anterior tibia is at a distance greater than 0.125 inch distal from the intercondylar sulcus.
insufficient CR angulation.
How is the knee positioned to superimpose the medial and lateral surfaces on the AP axial projection?
internally rotate at AP projection, with femoral epicondyles parallel with the IR.
How are the legs positioned to prevent rotation on a tangential knee projection?
internally rotate the legs and secure them by wrapping the velcro straps of the axial viewer around the patients calves.
How is the CR aligned with the femorotibial joint space and tibial plateau to demonstrate them as open spaces on an AP knee projection?
parallel with it
On an AP axial knee projection, the medial and lateral aspects of the intercondylar fossa are not superimposed, the lateral femoral condyle is larger than the lateral condyle, and the fibular head demonstrates decreased tibial superimposition. How is the patient mispositioned?
that patients leg was internally rotated.
On a lateral knee projection, the distal articulating surfaces of the femoral condyles are demonstrated without superiorposition. The condyle that has the adductor tubercle attached to it is demonstrated approximately 0.25 inch distal to the other condyle. How is the patient mispositioned?
the CR was angled too caudally
On an AP knee, the medial femorotibial joint space is closed, and the fibular head is elongated and demonstrated less than 0.5 inch distal to the tibial plateau. How is the patient mispositioned?
the CR was angled too caudally
On an AP knee, the femorotibial joint spaces is obscured, the tibial plateau is demonstrated, and the fibular head is foreshortened and demonstrated more than 0.5 inch distal to the tibial plateau. How is the patient mispositioned?
the CR was angled too cephalically
On an internally rotated knee projection, the femorotibial joint space is obscured, and the fibular head is foreshortened and demonstrated more than 0.5 inch distal to the tibial plateau. How is the patient mispositioned?
the CR was angled too cephalically
On an AP axial knee projection, the knee joint space is closed, and the fibular head is shown more than 0.5 distal to the tibial plateau. How is the patient mispositioned?
the distal lower leg was elevated too high, or the CR was angled too cephalically.
How can one determine if an internally rotated AP oblique knees projection is over rotated?
the femoral condyles will be nearly superimposed
On an AP axial knee projection, the proximal surfaces of the intercondylar fossa are not superimposed, and the patellar apex is demonstrated proximally to the intercondylar fossa. How is the patient mispositioned.
the femur was angled less than 60 degress with the imaging table.
On an AP axial knee projection, the proximal surfaces of the intercondylar fossa are not superimposed, and the patellar apex is demonstrated within the intercondylar fossa. How is the patient mispositioned?
the femur was angled more than 60 degrees with the imaging table.
On a tangential patella projection, a portion of the proximal lower leg does not superimpose the distal femur and the patella is lateral to the intercondylar sulcus. How is the patient mispositioned?
the foot is placed lateral to the hip.
On a PA axial knee projection, the proximal surfaces of the intercondylar fossa are demonstrated without superimposition, and the patella is positioned within the intercondylar fossa. How is the patient mispositioned?
the knee was overflexed; the femur was too close to vertical
On an externally rotated knee projection, the fibula is not entirely superimposed by the tibia. How is the patient mispositioned?
the knee was rotated less than 45 degrees
On an internally rotated knee projection, the tibia is partially superimposed over the fibular head. How is the patient mispositioned?
the knee was rotated less than 45 degrees.
On an externally rotated knee projection, the lateral femoral condyle is superimposed over the medial condyle, and the fibula is located in the center of the tibia. How is the patient mispositioned?
the knee was rotated more than 45 degrees
On a PA axial knee projection, the proximal surfaces of the intercondylar fossa are demonstrated without superimposition, and the patella is positioned too far proximally to the interconylar fossa. How is the patient mispositioned?
the knee was underflexed; the femur was more that 20-30 degrees from vertical
On a PA axial knee projection, the medial and lateral aspects of the intercondylar foassa are demonstrated without superimposition, the patella is situated medially and the tibia is demonstrated without fibular head superimposition. How is the patient mispositioned?
the knees are wider apart than hip width, or the heel was laterally rotated.
On an AP knee projection, the medial femoral condyle appears larger than the lateral condyle, and the head, neck, and shaft of the fibula are almost entirely superimposed by the tibia. How is the patient mispositioned?
the leg was externally (laterally) rotated
On an AP knee, the lateral femoral condyle appears larger than the medial condyle, and the tibia demonstrates very little superimposition of the fibular head. How is the patient mispositioned?
the leg was internally (medially) rotated.
Is the proximal tibia superimposed over the proximal fibula or is the proximal fibula superimposed over the proximal tibia when the knee is in an AP projection?
the proximal tibia is superimposed over the proximal fibula
Why is it necessary to vary the degree of CR angulation for AP knee projections in patient with different upper thigh and buttock thincknesses?
the thicker the upper thighm the more the leg slopes down toward the IR, causing the tibial platuae to be at a different angle with the IR.
When is it necessary to use a cephalic CR angulation for a crosstable lateral knee projection in a patient in a supine position?
then the leg is laterally abducted
PA axial projection (weigth-bearing bilateral flexed): there is increased demonstration of intercondylar fossa. How is the patient mispositioned?
there is increased tilt between the long axis of the femur and IR.
What is the degree of knee flexion for the following? A) Inferiosuperior:____________ B) Settegast:___________
A) 45 degrees B) 90 Degrees
Which anatomic structures structures are included on a lateral knee projection with accurate positioning?
1/4 of the distal femur and proximal lower leg and surrounding soft tissue.
For an AP oblique knee projections, an imaginary line drawn between the femoral epicondyles should form an _______ degree angle with the IR.
45
What are the standard direction and degree of CR angulation used for the tangential knee projection?
60 degrees caudually
PA axial Projection (Holmblad Method): The medial and lateral surfaces of the intercondylar fossa and the femoral epicondyles are in profile, and (A)__________ of the fibular head superimposes the proximal tibia. The proximal surface of the intercondylar fossa is in (B)___________, and the patellar apex is demonstrated (C)______________ to the intercondylar fossa. The knee joint space is (D)________, and the tibial plateau and intercondylar eminence and the tubercles are in profile. The fibular head is demonstrated approximately 0.25 (E)___________ to the tibial plateua. The (F)__________ is at the center of the exposure field.
A) 1/2 B) profile C) proximal D) open E) distal F) intercondylar fossa
To superimpose the proximal surfaces of the intercondular fossa in a PA axial knee projection, position the patient's femur at (A)________________ degrees from vertical or (B)_____________ degrees from the imaging table.
A) 20-30 B) 60-70
AP Oblique Knee: The femorotibial joint space is open, the anterior and posterior margins of the tibia are aligned, and the fibular head is approximately 0.5 inch (A)________ to the (B)____________. Medial oblique: The fibular head is seen free of (C)___________superimposition., and the lateral femoral condyle is in profile without superimposing the medial condyle. Lateral oblique: the fibular head is aligned with the (D)___________ edge of the tibia, and the medial femoral condyle is in profile without superimposing the lateral condyle. The (E)____________ is at the ceter of the exposure field.
A) distal B) tibial plateau C) tibial D) anterior E) knee joint
When the knee is flexed, the patella shifts (A)________________ (proximally/distally) and (B)_________ (medially/laterally) onto the patellar surface of the femur and then (C)________ (medially/laterally) onto the intercondylar fossa.
A) distally B) medially C) laterally
An AP knee projection is obtained by placing the patient supine with the knee (A)______ and leg (B)______ rotated until the femoral epicondyles are placed at (C)________ from the IR.
A) extended B) internally C) equal distance (parallel)
AP axial Knee: The intercondylar fossa is shown in it entirety, the medial and lateral surfaces of the intercondylar fossa and the (A)__________ are in profile, and the tibia superimposes 1/2 of the (B)___________. The proximal surface of the intercondylar fossa is in profile, and the patellar apex is demonstrated (C)____________ to the intercondylar fossa. The knee joint space is open, the intercondylar eminence and tubercles are in profile, and the fibular head is demonstrated approximately (D)_____________ inches distal to the tibial plateau. The (E)____________ is at the center of the exposure field.
A) femoral epicondyles B) fibular head C) proximally D) 1/2 inch E) intercondylar fossa
Tangential Patella: Merchant The patellae, anterior femoral condyles, and intercondylar sulci are seen superiorly, and the (A)________ femoral condyle demonstrates slightly more height than the (B)__________ condyle. The patellofemoral joint spaces are (C)____________ with no superimposition of the patellae or tibial tuberosities. A point midway between the (D)__ is at the center of the exposure field.
A) lateral B) medial C) open D) patellofemoral joint space
Which knee compartment on an AP knee projection is the narrower when a valgus deformity is present? A)___________ When a varus deformity is present? B)_______________
A) lateral compartment B) medial compartment
State two methods of distinguishing the medial femoral condyle from the lateral femoral condyle on a lateral knee projection with poor positioning. A)__________ B)________________
A) locate the adductor tubercle on the posterior aspect of the medial condyle B) locate the distal articulating surface that is the flattest. It is the lateral condyle.
When the average patient is placed in a recumbent lateral position for a lateral knee projection, the femoral shaft inclination displayed in the erect position is reduced, causing the (A)______ condyle to be projected (B)_________ to the (C)___________ condyle.
A) medial B) distal C) lateral
The CR is centered to the (A)______ at the level of the (B)___________ for AP oblique knee projections
A) midline of the knee B) knee joint
Tangential projection: Inferiosuperior and Settegast Inferiosuperior: Lateral femoral condyle demonstrates (A)______ height than the (B)__________ condyle. Settegast: Distal aspect of the (C)____ condyles are in profile. Patella is centered (D) ___________ to the intercondylar sulcus. The (E)__________ is at the center of the exposure field. The (F)______________ and (G)_________ are seen with minimal distortion.
A) more B) medial C) femoral D) superior E) patellofemoral joint F) patella G) femoral condyles
When a patient is erect, the distal femoral condylar surfaces are aligned (A)___________ to the floor, and the femoral shaft inclines (B)_________ up to (C)___________ degrees. A patient who demonstrates the greatest femoral inclination will have a (D)___________ (wide/narrow) pelvis, and (E)___________ (long/short) femoral shaft length.
A) parallel B) medially C) 10 D) wide E) short
The tangential knee prjection is most often obtained to demonstrate which patient condition? A)_______ How is this condition demonstrated on a tangential knee projection with accurate positioning? B)________________ How can one distinguish this condition from rotation on the radiograph?
A) patellar subluxaton B) the Patella will be demonstrated laterally C) the intercondylar sulci will remain facing superiorly on a subluxed patella but not on a rotated one.
Accurate CR centering on a PA axial knee projection is accomplished by centering an (A)__________ CR to the midline of the knee at the level (B)_____________ inches distal to the palpable (C)_________.
A) perpendicular B) 1 C) medial femoral epicondyle
AP Knee: The medial and lateral femoral epicondyles are in (A)____________, the femoral condyles are symmetrical, the intercondylar eminence is centered within the intercondylar fossa, and the tibia is superimposed over (B)_________ of the fibular head. The femorotibial joint space is open the anterior and posterior distal tibial margins are aligned, and the fibular head is demonstrated approximately 0.5 inch distal to the (C)_______________. The patella lies just (D)______________ to the patellar surface of the femur and is situated slightly (E)____________ to the knee midline. The (F)-_____________ is at the center of the exposure field.
A) profile B) 1/2 C) tibial plateau D) proximal E) lateral F) knee joint
If the wrong CR angle is used for an AP knee projection, the shape of the fibular head and its proximity to the tibial plateau change from that demonstrated on an AP knee projection in which an accurate CR angle was used. For each situation that follows, state the change that occurs A) CR angle too cephalically:_________ B) CR angled too caudally: ___________
A) the fibular head will be foreshortened and demonstrated more than 1/2 inch distal to the tibial plateau. B) the fibular head will be elongated and demonstrated less than 1/2 inch distal to the tibial plateau.
Which direction does the patella move when the patient is positioned for a PA axial knee projection and the heel is rotated as indicated below? A) internally:_______________ B) externally:_________________
A) the patella rotated laterally B) the patella rotates medially
What is the relationship between the tibia and the fibular head on a lateral knee projection with accurate positioning if superimposed condyles were obtained by aligning the femoral epicondyles perpendicular to the IR and directing the CR across the femur to project the medial condyle anteriorly and proximally? A)____________ How will this relationship change if superimposed condyles are obtained by rolling the patients patella approximately 0.25 inch closer to the IR and directing the CR toward the femur so it only moves the medial condyle proximally? B)________________
A) the tibia will be partially superimposed over the fibular head. B) the fibula will be demonstrated free of tibial superimposition.
How do the positions of the patellae and femoral condyles change when the knees are in external rotation for a tangential knee projection? A) Patellae:_______________ B) Femoral Conyles: ________________
A) they will be situated laterally B) the condyles will demonstrate equal heights, or the medial condyle will demonstrate more height than the lateral condyle.
where are the posterior knee curves positioned with respect to the axial viewer for a tangential knee projection with accurate positioning?
Directly above the bend of the axial viewer until the knees are flexed 45 degrees.
Why is the medial condyle shifted more than the lateral condyle when the degree of CR angulation is adjusted?
Because it is situated farthest from the IR.
Why is it important for the patient to relax the quadriceps femoris muscles for the tangential knee projection?
Because tightening the quadriceps muscles will prevent patella subluxation from being demonstrated
Should the patients abdominal thickness be included in the anterior superior iliac spine (ASIS) to-image table measurement obtained for a patient undergoing AP knee imaging?
No
How are the femurs positioned to obtain a tangential knee projection with accurate positioning?
Parallel with the imaging table
Which anatomic structures are included on a tangential knee projection (inferiosuperior) with accurate positioning?
Patella, femoral condyles surfaces, and intercondylar sulci
On a merchant tangential patellae, the patellae are demonstrated directly above the intercondylar sulci, and rotated laterally. The medial femoral condyles demostrate more height than the lateral condyles. How is the patient mispositioned?
The legs were externally rotated
Describe the slope of the tibial plateau
Th tibial plateau slopes approximately 3-5 degrees anterior to posterior
Which anatomic structures are included on a PA axial knee projection with accurate positioning?
The distal femur, proximal tibia, and intercondylar fossa, eminence. and tubercles.
On an AP axial knee projection, the knee joint space is closed, and the fibular head is shown less than 0.5 inch distal to the tibial plateau. How is the patient mispositioned?
The distal lower leg was depressed, or the CR was angled too caudally
If the medial condyle is demonstrated anterior to the lateral condyle on a lateral knee projection with poor positioning, what the tibia mad fibular relationship be?
The fibula will be demonstrated with decreases or without tibial superimposition.
If the lateral condyle is demonstrated anterior to the medial condyle on a lateral knee projection with poor positioning, what will the tibia and fibular relationship be?
The fibula will be demonstrated with increased or complete tibial superimposition.
How can one determine if an externally rotated AP oblique knee projection was overrotated?
The fibular head will not be aligned with the anterior edge of the tibia but will be positioned posterior to the placement.
On a merchant tangential patellae projection, soft tissue from the patient's anterior thighs has been projected onto the patellae and patellofemoral joint space. How is the patient mispositioned?
The height of the axial viewer was not set high enough to position the long axes of the femurs parallel with the imaging table.
On later knee projection, the patients patella is in contact with the patellar surface of the femur, and the suprapatellar fat pads are obscured. How is the patient mispositioned?
The knee was overflexed
On an PA axial knee projection, the medial and lateral aspects of the intercondylar fossa are demonstrated without superimposition, and the patella is situated laterally/ How is the patient mispositioned?
The knees are closer together than hip width, or the heel was medially rotated.
If the patients leg is not internally rotated to accurately position the femoral condyles on an AP knee, how will the appearances of the femoral condyles and the alignment of the tibia and fibula change?
The medial condyle will appear larger than the lateral condyle, and the head , neck, and possibly the shaft of the fibula will be superimposed by the tibia.
On later knee projection, the anterior and posterior aspects of the femoral condyles are demonstrated without superimposition. The medial condyle is demonstrated posteriorly. How is the patient mispositioned?
The patella was situated too far away from the IR (leg internally rotated)
Which anatomic structures are included on a tangential knee projection with accurate positioning.
The patelllae, anterior femoral condyles, and intercondylar sulci
An AP knee projection is requested for a patient who is unable to fully extend the knee. The technologist angled the CR until it was perpendicular to the anterior surface if the lower leg and obtained a 10 degree cephalic angle. How is this angle adjusted to align the CR parallel with the tibial plateau and obtain an open femorotibial joint?
decrease the angulation approximately 5 degrees to align it with the tibial plateau.
If the knee id flexed more than needed to superimpose the proximal surfaces of the intercondylar fossa, is the patella demonstrated proximally or distally to where it is demonstrated on an AP axial knee projection with accurate positioning?
distally
