Positioning: Hip and Proximal Femur (CH 7)
What is the unilateral frog-leg projection?
--also called the modified Cleaves method -abduct femur 45degrees from vertical --(for best demonstration of femoral head and acetabulum, abduct femur 90degrees form vertical) -CR perp to midfemoral neck
What is the posterior oblique - Acetabulum (Judet method)?
-2 projections -one with affected side down -recumbent 45degree posterior oblique -CR 2 inches (5 cm) distal and medial to downside ASIS -one with affected side up -CR 2 inches (5 cm) distal to upside ASIS -Perpendicular to IR
What is the criteria for a unilateral frog leg
-45° abduction (20°-30° abduction-less distortion of femoral neck) -Entire femoral head, neck, and trochanters centered to IR -Femoral head and neck in profile -Optimal exposure factors
A PT comes in complaining of pain and know known injury to the hip, what radiograph do you do first?
-AP pelvis (true, w/ internatl rotation) -frog-leg of affected hip side
What is the AP Bilateral frog-leg projection?
-Abduct femora 40°-45° -CR 3 inches (7.5 cm) below level of ASIS -20°-30° abduction-less distortion of femoral neck Patient position Supine Part position for bilateral No rotation of pelvis ASIS equal distance from table top Flex hips and knees Draw feet up as much as possible Abduct thighs equally and maximally Place soles of feet together for support Center IR 1˝ (2.5 cm) above pubic symphysis CR Perpendicular to MSP at level 1˝ (2.5 cm) above pubic symphysis Collimated field Size of IR
What are the other names for a cross-table lateral hip projection?
-Axiolateral hip -Inferosuperior hip -Danelius-Miller Method
What is the Axiolateral hip radiograph?
-CR perp to midfemoral neck -flex knee and hip of unaffected limb to place thigh vertical -rest unaffected leg and foot on a support -no rotation -rotate affected limb 15-20degrees medially -IR should be vertical with upper border in crease above iliac crest -angle lower border away form body until parallel with femoral neck -support IR in position
What is the hip and proximal femur (AP unilateral hip) projection?
-CR perp to midfemoral neck -no rotation of pelvis -true AP, rotate lower limb 15-20 degrees inward --so femoral neck is parallel to IR -top of IR should be at the ASIS
Where should your CR be placed for an AP unilateral hip?
-CR perp to midfemoral neck -top of the light field should be at the ASIS
For the AP Axial Outlet Projection (Taylor Method) how should the tube be angled for females?
-CR: 35-45degrees cephalad for females CR: centered 1-2 inches distal to the symphysis pubis
What is the positioning for a lateral mid-distal femur?
-Flex knee 45degrees (unaffected knee behind the affected knee so its out of the way) -lower light field should be 2'' below the knee joint(apex of patella)
What shielding should be used for hip radiographs?
-Gonadal shielding can be used on both male and females for hip if placed correctly. Not commonly used on pelvis exams. Male: Small contact shield, top border at inferior margin of symphysis pubis Female: Ovarian shield for hips and proximal femora
How do the obturator foramen affect rotation?
-Obturator foreamen are symmetric if one is narrower then the other there is rotation. -The larger foreamen is the side rotated down
AP pelvis radiograph
-Rotate limbs internally (nontrauma) -CR midway between level of ASIS and symphysis pubis Patient position - supine Part position MSP of body centered to midline Equal ASIS to table distance on both sides Medially rotate feet and lower limbs 15 to 20 degrees Places femoral necks parallel with IR Do not rotate if trauma or other pathology suspected Upper border of IR 1˝ to 1.5˝ inches (2.5 to 3.8 cm) above crests CR Perpendicular to IR Collimated field Size of IR
How do you tell if there's rotation in an AP mid-distal femur radiograph?
-The femoral and tibial condyles should seem symmetric in size and shape ---if they aren't there is rotation -The outline of the patella will be toward the medial side
what is the modified axiolateral?
-also called Clements-Nakayama Method -CR 30°-40° mediolateral and 15°-20° posteriorly from horizontal -CR centered to femoral neck
How should the femoral necks be in an AP pelvis radiograph?
-it should NOT be foreshortened/without superimposition
What needs to be included in a lateral mid-distal femur?
-knee joint (minimum) -distal 2/3 of the femur -superimposed anterior surface of the femoral condyles --inferior surface of the femoral condyles not superimposed due to divergent rays -patella in profile --open patella femoral joint
What needs to be included in the AP mid-distal femur radiograph?
-knee joint --(won't appear open due to the divergent rays) -distal 2/3 of the femur
What needs to be included in an AP unilateral hip radiograph?
-proximal 1/3 of femur -greater trochanter in profile(lesser should not or only slightly visible) -Entire long axis of femoral neck without foreshortening -acetabulum -total existing orthopedic "hardware" if applicable
What needs to be visualized for an axiolateral hip radiograph?
-the entire femoral head, neck(w/out overlap from greater trochanter), and acetabulum --only a small amount of greater trochanter on anterior and posterior surface of proximal femur -grid lines should NOT be seen
Where should the CR be for an AP (mid-distal) Femur
-the lower edge of the light field should be 2'' below the knee joint (apex of patella)
How do you tell if there is rotation of a pelvis?
-there is rotation if one ilia is larger than the other --it is rotated toward the larger side (ex. if the right side is larger then it is rotated toward the right) -you can also look at the obterater foramen, they should be equal in size, open the same amount, if they aren't then there is also rotation
What is the Frog Lateral mid-proximal femur
-true lateral -proximal femur not superimposed -affected side down, knee flexed, PT roll back about 15 degrees to prevent superimposition from opposite thigh -place upper IR light field line at the level of the ASIS
What size cassette do you use for the AP unilateral hip?
10X12 --unless the PT has previously had a orthopedic surgery, then you need to include all of the "hardware" and may need to go to a 14X17
Neck projects anteriorly ____________ degrees.
15-20
How much should you rotate the toes and entire leg inward for the AP unilateral hip? -Why do we do this?
15-20degrees -b/c so the femoral head is parallel to the IR
What are the bones of the pelvis?
4 bones, -2 hip bones (ossa coxae, and innominate bones) -sacrum -coccyx
What needs to be ruled out before attempting the frog-leg projections?
A fracture
What type of CR angle is required for the AP axial "outlet" projection for a male patient? A: 20° to 35° cephalad B: 30° to 45° cephalad C: 45° to 60° cephalad D: 40° caudad
A: 20° to 35° cephalad
What is the joint classification of the symphysis pubis? A: Amphiarthrodial B: Synarthrodial C: Diarthrodial D: The symphysis pubis is fused; therefore it is not an actual joint
A: Amphiarthrodial
Which of the bones of the pelvic girdle is the largest? A: Ilium B: Ischium C: Pubis D: Coccyx
A: Ilium
How is the cassette aligned for an axiolateral (Danelius-Miller method) projection? A: Parallel to femoral neck B: Parallel to greater trochanter C: Perpendicular to iliac crest D: Parallel to long axis of femoral shaft
A: Parallel to femoral neck
LPO upside criteria?
Anterior rim and posterior ilioischial column demonstrated
To minimize distortion of the femoral neck for an AP bilateral frog-leg projection, the lower limbs should be abducted: A: 10° to 15° B: 20° to 30° C: 45° D: 90°
B: 20° to 30°
Which bony landmark should NOT be visible on a correctly positioned AP pelvis (nontrauma)? A: Greater trochanter B: Lesser trochanter C: Ischial spines D: Ischial tuberosity
B: Lesser trochanter
Where is the CR centered for an AP pelvis projection? A: Level of iliac crest B: Level of ASIS C: Midway between ASIS and symphysis pubis D: Level of symphysis pubis
C: Midway between ASIS and symphysis pubis
The depression or pit located at the center of the femoral head is the: A:Acetabulum B:Femoral fossa C:Fovea capitis D:Ossa coxa
C:Fovea capitis
What is the AP Axial inlet projection?
CR 40degrees caudad at level of ASIS
For the AP Axial Outlet Projection (Taylor Method) how should the tube be angled for males?
CR: 20-35degrees cephalad for males -CR centered 1-2'' distal to symphysis pubis
Which of the following projections is best suited for the patient with limited movement of both lower limbs to demonstrate a lateral perspective of the proximal femur? A: Taylor method B: Danelius-Miller method C: Judet method D: Clements-Nakayama method
D: Clements-Nakayama method
Which of the following bony landmarks is located posterior to the acetabulum? A: ASIS B: Ischial tuberosity C: Iliac crest D: Ischial spine
D: Ischial spine
What is the criteria for the modified axiolateral hip?
Entire femoral head, neck, and trochanters centered to IR Femoral head and neck in profile Optimal exposure factors
How can you tell the difference between a male and female pelvis?
Female: -pelvis is wider, ilia are more flared and more shallow from front to back -pubic arch is >90 -inlet is larger and more round Male: -narrower, deeper and ilia are less flared -pubic arch is <90 -inlet is more narrow and oval or heart shaped
What projection is done for the proximal femur?
Hip and proximal femur - AP unilateral hip
How do you find the head and neck of the femur for CR placement?
Method 1=1st determine the midline between the ASIS and sympysis --neck 2.5" head 1.5" distal form the midline Method 2 (because you may not always be able to locate the symphysis=1-2 inches medially and 3-4 inches inferior
RPO downside criteria?
Posterior rim and anterior ilioischial column demonstrated
What is the criteria for an AP unilateral hip and proximal femur projection
Proximal ⅓ of femur included Hip joint space and acetabulum visualized Lesser trochanter not visible or only slightly visible Total existing orthopedic prosthesis demonstrated Optimal exposure factors
TRUE/FALSE: The greater trochanter is in profile and the lesser trochanter can not be seen; the leg is internally rotated.
TRUE
TRUE/FALSE: The pubic arch of the male pelvis forms an acute angle (<90°)?
TRUE
The AP Axial outlet projection is also called what?
Taylor method
What angle is the one that requires us to rotate the feet inward for positioning of the pelvis in order to place the femoral neck parallel to the IR for a true AP?
The anterior angle
What is the true pelvis?
True pelvis: inside the brim of the pelvis also called the lesser pelvis false pelvis: outside the brim of the pelvis, also called the greater pelvis
How much is the femur angled in the anatomical position?
about 10degrees
What is the angle of the femur body, longitudinal?
about 10degrees
What is the angle of the femur neck to shaft?
about 125degrees
What is the anterior angle of the femur?
about 15-20degrees
The sacrum and coccyx should be aligned with what?
aligned with the pubis symphysis
What kind of joint is the symphysis pubis joint?
cartilaginous ------> amphiarthroidal w/ limited movement
what kind of joint is the union of the acetabulum joint?
cartilaginous ------> synarthrodial w/ immovable movement
What should you do in a trauma situation and you need to get a lateral mid-distal femur?
do a cross-table lateral
What are the 4 primary parts of the femur?
head, neck, greater trochanter, and lesser trochanter
When should you NOT rotate the foot and leg inward to allow the femoral neck to be parallel to the IR?
if there is a possible fracture
If in a AP Axial Outlet Projection (Taylor Method) radiograph the obturator foramina are foreshortened what should you do?
increase the CR angle
For the AP axial inlet projection how should the ischial spines appear? -pelvic inlet?
ischial spines should be demonstrated and equal -pelvic inlet should be centered
For the AP bilateral frog leg projection how should the trochanters be?
lesser trochanter: -equal in size -on medial side of femur greater trochanter: -superimposed over femoral neck
What must you do to achieve a true AP femur?
rotate the feet and entire leg inward about 5degrees so the femoral neck is parallel to the IR
What are the parts of the hip bone?
superior to inferior -ilium -acetabulum -pubis -ischium all fuse together at the acetabulum but are separate bones as children
what kind of joint is the hip joint?
synovial -----> diarthroidial w/ spheroidal movement
What kind of jjoint is the sacroiliac?
synovial ----> amphiarthroidal w/ limited movement
What should be in profile for an AP unilateral hip radiograph?
the greater trochanter should be in profile --lesser trochanger should only slightly or not at all be seen(if it is in profile it its externally rotated and the neck will be foreshortened)
If both feet are together with no rotation what will be visible?
the lesser trochanter
If you externally rotate the leg, what will be visible to know that if was externally rotated?
the lesser trochanter