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Lower limb positions
Ch 6-7 Bontrager
Question | Answer |
---|---|
What is the basic positioning routine for a study of the tibia and fibula? | AP and lateral projections |
Why is it important to include the knee joint for an initial study of tibia trauma, even if the patient's symptoms involve the middle and distal aspect? | A fracture may also be present at the proximal fibulas as well as the distal portion |
What is the central ray angulation for an AP projection of the knee for a patient with thick thighs and buttocks (greater than 24 cm)? | 3 to 5 degrees cephalad |
Where is the CR centered for an AP projection of the knee? | 1/2 inch distal to apex of patella |
Which basic projection of the knee best demonstrates the proximal fibula free of superimposition? | AP oblique, 45 degrees medial rotation |
For an AP oblique of the knee, the ________________ best visualized the lateral condyle of the tibia and the head and neck of the fibula. | Medial (internal) |
What is the recommended CR placement for a lateral knee position on a tall, slender male patient with a narrow pelvis (without support of the lower leg)? | 5 degrees cephalad |
How much flexion is recommended for a lateral knee projection? | 20 to 30 degrees |
Which positioning error is present if the posterior portions of the femoral condyles are not superimposed on a lateral knee projection? | Over rotation towards the IR or under rotation of the knee (away from IR) |
Which positioning error is present if the distal borders of the femoral condyles are not superimposed on a lateral knee projection on an average knee? | Improper angle of the CR or lack of support of the lower leg |
Which anatomic structure of the femur can be used to determine which rotation error (over rotation or under rotation) is present on a slightly rotated lateral knee projection? | Adductor tubercle on posterolateral aspect of the medial femoral condyle |
Which special projection of the knee best evaluates the knee joint for cartilage degeneration or deformities? | AP or PA weight bearing knee |
What is the best modality to examine ligament injuries to the knee? | MRI |
Which special projection of the knee best demonstrates the intercondylar fossa? | Holmblad |
How much flexion of the lower leg is required for the PA axial projection (Camp-Coventry method) when the CR is angled 40 degrees caudad? | 40 degrees flexion |
Why is the PA axial projection for the intercondylar fossa recommended instead of an AP axial projection? | Distortion caused by CR angle and increased OID for AP axial projection |
What type of CR angulation is required for the PA axial weight bearing projection (Rosenburg method)? | 10 degrees caudad |
How much flexion of the knees is required for the PA axial weight bearing projection (Rosenburg method)? | 45 degrees |
How much knee flexion is required for PA axial (Holmblad method)? | 60 to 70 degrees |
What type of CR angle is required for the PA axial (Holmblad method)? | None, CR is perpendicular |
To place the interepicondylar line parallel to the IR for a PA projection of the patella, the lower limb must be rotated approximately 5 degrees internally. | True |
How much part flexion is recommended for a lateral projection of the patella? | 5 to 10 degrees |
How much central ray angle from the long axis of the femora is required for the tangential (Merchant method) bilateral projection? | 30 degrees from horizontal |
How much part flexion is required for the Hughston method? | 55 degrees |
How much part flexion is required for the Settegast method? | 90 degrees |
What type of CR angle is required for the superoinferior sitting tangential method for the patella? | None, CR is perpendicular |
Which special projection must be performed erect? | Rosenburg method |
The recommended SID is 48 inches to 72 inches for the tangential (bilateral Merchant) projection. | True |
How much knee flexion is required for the horizontal beam lateral patella projection? | None |
A radiograph of an AP oblique-medial rotation projection of the foot reveals that the proximal third to fifth metatarsals are superimposed. What type of positioning error led to this radiographic outcome? | Over rotation of foot (toward medial direction) |
A radiograph of a plantodorsal axial projection of the calcaneus reveals considerable foreshortening of the calcaneus, what type of positioning modification is needed on the repeat exposure? | Increase cephalad angle of CR to correctly elongate the calcaneus |
A radiograph of an intended AP mortise projection reveals that the lateral malleolus is superimposed over the talus, and the distal tibiofibular joint is not well demonstrated. What is the most likely reason for this radiographic outcome? | Under rotation of the ankle (toward medial direction). The described appearance is that of a true AP ankle with little or no obliquity |
A patient with a possible Lisfranc joint injury. Which radiographic position(s) best demonstrates this type of injury? | AP and lateral weight bearing foot projections |
The articular facets slope _________________ posteriorly. | 10 to 20 degrees |
If a foreign body is lodged in the plantar surface of the foot, which type of central ray angle should be used for the AP projection? | None, perpendicular CR |
Why is the CR angled 10 to 15 degrees toward the calcaneus for an AP projection of the toes? | Opens up the interphalangeal and metatarsophalangeal joints |
How should the CR be angled from the long axis of the foot for the plantodorsal axial projection of the calcaneus? | 40 degrees cephalad |
How much (if any) should the foot and ankle be rotated for an AP mortise projection of the ankle? | 15 to 20 degrees medially |
Which projection of the ankle requires inversion and eversion movements? | AP stress projections |
The former name for "runner's knee"? | Chondromalacia patellae |
What is another term for osteomalacia? | Rickets |
Can be performed using a wheelchairor lowered radiographic table. | Holmblad method |
Patient prone with 40 to 50 degree knee flexion and with equal 40 to 50 degree caudad CR angle. | Camp-Coventry method |
Patient prone; requires 90 degree knee flexion | Settegast method |
IR is placed on a foot stool to minimize the OID | Hobbs method |
Patient prone with 55 degree knee flexion and 15 to 20 degree CR angle from long axis of lower leg. | Hughston method |
Patient is supine with cassette resting on midthighs. | Inferosuperior for patellofemoral joint |
Patient supine with 40 degree knee flexion and with 30 degree caudad CR angle from horizontal | Merchant modification |
Asymmetric erosion of joint spaces with calcaneal erosion. | Reiter's syndrome |
Uric acid deposits in joint space. | Gout |
Well-circumscribed lucency. | Bone cyst |
Small, round/oval density with lucent center. | Osteoid osteoma |
Narrowed, irregular joint surfaces with sclerotic articular surfaces. | Osteoarthritis |
Fragmentation or detachment of the tibial tuberosity. | Osgood-Schlatter disease |
Ill-defined area of bone destruction with surrounding "onion peel". | Ewing's sarcoma |
Decreased bone density and bowing deformities of weight bearing limbs. | Osteomalacia |
Injury to a large ligament located between the bases of the first and second metatarsals. | Lisfranc joint injury |
A degenerative joint disease. | Osteoarthritis |
Most common fracture in older patients because of high incidence of osteoporosis or avascular necrosis. | Proximal hip fracture |
A malignant tumor of the cartilage of the hip. | Chondrosarcoma |
a disease producing extensive calcification of the longitudinal ligament of the spinal column | Ankylosing spondylitis |
A fracture resulting from a severe blow to one side of the pelvis. | Pelvic ring fracture |
Malignancy spread to bone via the circulation and lymphatic systems or direct invasion. | metastatic carcinoma |
Now referred to as developmental dysplasia of the hip. | Congenital dislocation |
An imaginary plane that divides the pelvic region into the greater and lesser pelvic is called | Pelvic brim |
What is the major function for the greater pelvis (or false pelvis)? | Support the lower abdominal organs and fetus |
What is the major function for the lesser pelvis (or true pelvis)? | Forms the actual birth canal |
Which bony landmark is found on the most inferior aspect of the posterior pelvis? | Ischial tuberosity |
The ____________________ of the pelvis is the largest foramen in the skeletal system. | Obturator Foramen |
The upper margin of the greater trochanter is approximately ___________ degrees above the level of the superior border of the symphysis pubis, and the ischial tuberosity is about ___________ degrees below. | 1 inch; 1 1/2 to 2 inches |
Which two bony landmarks need to be palpated for a hip localization? | ASIS and symphysis pubis (or greater trochanter) |
Which physical sign may indicate that the patient has a hip fracture? | The patient's foot is rotated externally |
To achieve a true AP projection of the proximal femur, the lower limb must be rotated _________ internally. | 15 to 20 degrees |
What is the advantage of using 90 kV rather than a lower kV range for hip and pelvis studies on younger patients with an analog imaging system? | It reduces patient's dose |
What is the disadvantage of using 90 kV for hip and pelvis studies, especially on older patients with some bone mass loss with an analog imaging system? | It reduces radiographic contrast |
Where is the CR placed for an AP pelvis projection? | Midway between ASIS and symphysis pubis |
The central ray for an AP pelvis is approximately ________ inch(es) inches inferior to the level of the ASIS. | 2 |
When gonadal shielding is not used, does a male of female receive greater gonadal dose with an AP pelvis projection? | Females (because of location of CR and reproductive system) |
How many degrees are the femurs abducted (from the vertical plane) for the bilateral frog-leg projection? | 40 to 45 degrees |
Where is the CR placed for a bilateral frog-leg (modified cleaves method) projection? | 3 inches below level of ASIS; 1 inch above symphysis pubis) |
Where is the CR placed for an AP unilateral frog-leg projection? | Midfemoral neck |
What CR angle is required for the "outlet" projection (Taylor method) for a female patient? | 30 to 45 degrees cephalad |
What type of pathology is best demonstrated with the posterior oblique projection (Judet method)? | Acetabular fractures |
How much obliquity of the body is required for the posterior oblique projection (Judet method)? | 45 degrees |
What type of CR angle is used for a PA axial oblique (Teufel) projection? | 12 degrees cephalad |
How is the pelvis (body) positioned for a PA axial oblique (Teufel) projection? | PA 30 to 40 degrees toward affected side |
The axiolateral (inferosuperior) projection is designed for __________________ situations. | Traumatic |
The modified axiolateral requires the CR to be angled __________ posteriorly from horizontal. | 15 to 20 degrees |
What is the optimal amount of hip abduction applied for the unilateral "frog-leg" projection to demonstrate the femoral neck without distortion? | 20 to 30 degrees from vertical |
How much is the CR tilted for the modified axiolateral projection of the hip? | 15 degrees from vertical |
Which condition is a common clinical indication for performing pelvic and hip examinations on a pediatric (newborn) patient? | Developmental dysplasia of hip |
Which modality best demonstrates a possible pelvic ring fracture? | CT |
Which modality can be used on a newborn to assess hip joint stability during movement of the lower limbs? | Sonography |
Which modality is the most sensitive in diagnosing early signs of metastatic carcinoma of the pelvis? | Nuclear medicine |
A tear of the tibial (medial) collateral ligament (MCL) caused by a trauma injury is frequently associated with tears of the: | ACL and medial meniscus |
A radiograph of an AP pelvis demonstrates that the right obturator foramen is foreshortened but the left foramen is open. Which one of the following positioning errors is present on this radiograph? | Right rotation |
How many articular facets make up the subtalar joint? | Three |
What are the two arches of the foot? | Longitudinal and transverse |
The purpose of the AP stress views of the ankle is to demonstrate: | Possible joint separations or ligament tears |
Extending the ankle joint or pointing of the foot and toes downward is called: | Plantar Flexion |
The AP mortise projection of the ankle is commonly taken in surgery during open reductions. | True |
Which projection of the knee will best demonstrate the neck of the fibula without superimposition? | AP oblique with medial rotation |
Male or female: Pelvis is narrower, deeper, less flared; acute angle (less than 90 degrees); more oval or heart-shaped. | Male |
Male or female: Pelvis is wider, more shallow, more flared; obtuse angle (greater than 90 degrees); rounder, larger | Female |
Which bony structures cannot be palpated? | Ischial spine |
The term pelvic girdle refers to the total pelvis including the sacrum and coccyx. | False |
Which bone of the pelvic girdle forms the anterior inferior aspect? | Pubis |