Chapter 14 - Lower Limb and Pelvis Flashcards
foot is commonly divided into three basic parts:
the forefoot, the midfoot, and the hindfoot
The bones of the forefoot include
the phalanges and metatarsals.
The midfoot consists of
five short bones called tarsal bones
The hindfoot includes
the calcaneus and the talus
The calcaneus is commonly referred
to as the heel bone.
The talus articulates with the tibia and fibula to form
the ankle mortise
eversion
Lateral flexion of the ankle tends to roll the foot onto its medial aspect
inversion
Medial flexion causes the foot to roll onto its lateral aspect
tibia
The tibia is the longer, thicker bone on the medial side.
fibula
The fibula is much thinner and somewhat shorter and is located laterally.
medial malleolus
The medial malleolus is a bony prominence that can be palpated at the ankle on the medial aspect of the distal tibia.
lateral malleolus
The lateral malleolus is the rounded prominence on the distal aspect of the fibula and can be felt on the lateral aspect of the ankle.
knee
The distal articular surfaces of the condyles articulate with the tibial plateau to form the knee, which is a hinge-type joint.
meniscus
The articular surface of each condyle is cushioned by a C-shaped cartilage called a meniscus.
fovea capitis
A small indentation on its posterior superior surface is called the fovea capitis.
hip bones, also called the os coxae or innominate bones
The two bones that make up the halves of the pelvis. Each is a composite bone made up of three bones: the ilium, the ischium, and the pubis.
acetabulum
The ilium, ischium, and pubis join to form a synarthrodial joint at the acetabulum. The acetabulum is the rounded fossa that forms the socket of the hip joint. It articulates with the head of the femur.
Toes - AP or AP axial, AP oblique (medial rotation), and lateral projections
Body position
Seated or recumbent on table with knee flexed.
Part position
AP axial
Plantar surface supported on a 15-degree wedge sponge (Fig. 14.10).
AP
Plantar surface is in contact with IR (Fig. 14.11).
AP oblique
Medial plantar surface of toe and forefoot is in contact with IR. Plantar surface of foot and toes forms a 30- to 45-degree angle with IR (Fig. 14.13).
Lateral
Medial or lateral surface of foot may be in contact with IR, depending on which brings toe of interest nearest to IR. Other toes are flexed or extended as needed to leave affected toe free of superimposition. Affected toe is supported parallel to IR. Toes may be held in position using tape or a bandage (Fig. 14.15) or a wooden tongue blade. Positioning a single toe apart from the others often demands some creativity on the part of the radiographer. Variations may be required depending on which toe is involved, configuration of toe, and movements tolerable for the patient.
Central ray
AP axial
Angled 15 degrees posteriorly (toward heel) to MTP joints.
AP, AP oblique, and lateral
Perpendicular to MTP joints.
Structures seen
Entire digit and distal half of metatarsal with IP and MTP joint spaces open and clearly visualized (Figs. 14.12, 14.14, and 14.16).
sesamoids - tangential projection
Body position
Standing, facing away from collimator, or prone.
Part position
Plantar surface of foot resting on IR in a position of dorsiflexion, and adjusted to place the ball of the foot perpendicular to the IR (Fig. 14.17A). When the patient can’t stand, the tangential projection can be performed with the patient seated, the foot pointing up, and the plantar surface at an angle of approximately 70 degrees with the plane of the IR (Fig. 14.17B).
Central ray
Perpendicular and tangential to the first MTP joint.
Structures seen
Sesamoids and first metatarsal head in profile (Fig. 14.18).
Foot - AP axial, AP oblique (medial), and lateral projections.
Body position
Seated or recumbent on table with knee flexed. In podiatric practice, the AP (DP) and AP (DP) oblique projections are performed with the patient standing.
Part position
For all projections, foot is centered with regard to IR so that toes, heel, and both malleoli are within field.
AP axial
Plantar surface of foot is in contact with IR (Fig. 14.19).
AP oblique
Leg is rotated medially so that medial plantar aspect of foot is in contact with IR. Plantar surface of foot forms a 30-degree angle with IR (Fig. 14.21).
Lateral
Lateral aspect of foot is in contact with IR and foot is in true lateral position with plantar aspect of forefoot perpendicular to IR. Ankle is dorsiflexed so that long axis of foot is perpendicular to tibia (Fig. 14.23).
Central ray
AP axial
Angled 10 degrees posteriorly (toward heel) and entering base of third metatarsal.
AP oblique and lateral
Perpendicular to base of third metatarsal.
Structures seen
Entire foot, including toes, metatarsals, and tarsal bones. On AP axial projection, calcaneus is obscured by superimposition of lower leg (Fig. 14.20). AP oblique projection with medial rotation should demonstrate the metatarsals and some tarsals (cuboid, navicular, lateral cuneiform) with minimal superimposition on one another (Fig. 14.22). Too much superimposition of these structures indicates that angle between plantar surface of foot and IR was too great; that is, foot was everted too much. Lateral projection shows superimposition of metatarsals, more proximal than distal. It should include the ankle joint (Fig. 14.24).
Calcaneus - axial (plantodorsal) and lateral projections
Body position
Axial (plantodorsal)
Seated or recumbent on table with leg extended.
Lateral
Seated or recumbent on table with knee flexed.
Part position
Axial (plantodorsal)
Posterior surface of ankle and heel is in contact with IR. Place foot so that malleoli are centered with regard to middle of IR. Sagittal plane of foot is perpendicular to IR. Foot is dorsiflexed as much as possible and held in position by patient using a strap or bandage (Fig. 14.34).
Lateral
Lateral surface of heel is in contact with IR. Part is positioned as for lateral projection of foot but with calcaneus centered to IR (Fig. 14.36).
Central ray
Axial (plantodorsal)
Angled 40 degrees cephalad to center of IR, entering at third metatarsal base.
Lateral
Perpendicular to center of IR, entering about 1 inch (2.5cm) distal to medial malleolus.
Structures seen
Both projections demonstrate entire calcaneus and its articulation with talus (Fig. 14.35). Lateral projection also shows calcaneal articulations with cuboid and navicular anteriorly (Fig. 14.37).
Ankle - AP, AP oblique (medial rotation), AP oblique (medial rotation–mortise joint), and lateral projections.
Body position
AP and AP obliques
Seated or recumbent on table with affected leg extended.
Lateral
Recumbent or semirecumbent on affected side with knee flexed 30 to 45 degrees.
Part position
AP
Posterior surface of heel and lower leg is in contact with IR. Midpoint between malleoli is centered to IR. Foot is dorsiflexed so that plantar surface of foot forms a 90-degree angle with coronal plane of lower leg. Sagittal planes of leg and foot are perpendicular to IR (Fig. 14.39). Foot may be held in position by patient using a strap or bandage.
AP oblique (medial rotation)
From position for AP projection, entire leg is rotated medially 45 degrees. Sagittal planes of foot and leg must remain aligned to each other (Fig. 14.41).
AP oblique (medial rotation—mortise joint)
From position for AP projection, entire leg is rotated 15 to 20 degrees medially. Sagittal planes of foot and leg must remain aligned with each other (Fig. 14.43).
Lateral
Lateral surface (medial surface, if upright) of ankle is in contact with IR. Sagittal plane of foot and leg is parallel to IR. Foot is dorsiflexed so that plantar surface of foot forms a 90-degree angle with coronal plane of lower leg (Fig. 14.45).
Central ray
AP and AP obliques
Perpendicular to point midway between malleoli.
Lateral
Perpendicular to medial malleolus.
Structures seen
Superior portion of talus and distal portions of tibia and fibula (Fig. 14.40). AP oblique projection with a 45-degree medial rotation demonstrates tibiofibular joint without superimposition (Fig. 14.42). AP oblique projection with 15- to 20-degree medial rotation demonstrates mortise joint spaces without superimposition (Fig. 14.44). Lateral projection demonstrates tibiotalar and subtalar joints, and includes fifth metatarsal base (Fig. 14.46).
Lower Leg - AP and lateral projections
Body position
AP
Seated or recumbent on table.
Lateral
Recumbent on affected side with contralateral leg anterior or posterior to affected leg.
Part position
AP
Leg is fully extended with posterior surface of lower leg in contact with IR. Margin of IR is placed 1 to 2 inches beyond joint of primary interest. Foot is dorsiflexed so that plantar surface of foot forms a 90-degree angle with coronal plane of lower leg. Sagittal planes of leg and foot are perpendicular to IR (Fig. 14.50). Foot may be held in position by patient using a strap or bandage.
Lateral
Knee may be flexed, if necessary, to ensure a true lateral position. Lateral surface of lower leg is in contact with IR. Leg is rotated to place sagittal plane of leg parallel to IR and coronal plane through patella perpendicular to IR. Margin of IR is placed 1 to 2 inches beyond joint of primary interest (Fig. 14.52).
Central ray
Perpendicular to center of IR entering midshaft of tibia.
Structures seen
Entire lower leg and at least one joint (Figs. 14.51 and 14.53).
Knee - AP and lateral projections
Body position
AP
Seated or supine on table with leg extended.
Lateral
Recumbent on affected side with femur aligned with center of table. Unaffected leg is anterior or posterior to affected leg.
Part position
AP
Leg is fully extended with sagittal plane of leg perpendicular to IR (Fig. 14.54).
Lateral
Knee is flexed 20 to 30 degrees. Sagittal plane of femur and lower leg is parallel to IR (Fig. 14.56).
Central ray
AP
Entering 0.5 inch distal to apex of patella. Angle is variable, depending on the measurement between the ASIS and the tabletop, as follows:
<19cm (thin patient)
19 to 24cm
> 24cm (large pelvis)
3 to 5 degrees caudad
0 degrees (perpendicular)
3 to 5 degrees cephalad
Lateral
Angled 5 to 7 degrees cephalad entering 1 inch distal to medial epicondyle of femur.
Structures seen
Knee joint with portions of distal femur and proximal lower leg (Fig. 14.55). Lateral projection includes a profile of tibial tuberosity. It should demonstrate distal femur with condyles superimposed and joint space free of superimposition. Entire patella and retropatellar joint space should also be clearly visualized (Fig. 14.57).
