foot & ankle positioning

Posi%oning of the Lower Extremi%es

p. 242-‐289

On CR/DR-‐ high kVp has no effect on contrast/brightness

Toes: AP Axial-‐ Dorsoplantar p. 242


•  kVp-‐ 65-‐75 •  SID-‐ 37” •  IR-‐ 8”x10” crosswise for 2 per IR; Tabletop; Non-‐grid •  Pa%ent-‐ seated or supine on table •  Part-‐ flex knees; center IR on toes •  CR-‐ 15° posterior through MTP joint •  Angle-‐ 15° towards heel •  Sheld Gonads


Structures Shown •  14 phalanges of toes •  Distal por%ons of metatarsals •  IP joints


Evalua%on Criteria •  Proper collima%on •  No rota%on of phalanges; so\ %ssue width & midsha\

concavity equal on both sides •  Open IP & MTP joint spaces •  Toes separated •  Distal ends of metatarsals •  So\ %ssues & bony trabecular detail

Toes: AP Oblique-‐ Medial Rota%on p. 245


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10” crosswise for 2 images; Tabletop; Non-‐grid •  Pa%ent-‐ supine or seated on table; flex knee; sole of foot

res%ng on table •  Part-‐ medially rotate lower leg & foot; plantar surface at

30°-‐45° from IR •  CR-‐ perpendicular; enter 3rd MTP joint •  Sheld Gonads


Structures Shown •  Toes •  Distal por%on of metatarsals rotated medially


Evalua%on Criteria •  Proper collima%on •  All phalanges •  Oblique toes; more so\ %ssue width & midsha\ concavity on

side away from IR •  Open IP & 2nd-‐5th MTP joint spaces •  1st MTP joint (not always opened) •  Toes separated •  Distal ends of metatarsals •  So\ %ssue & bony trabecular detail

Toes: Lateral (Mediolateral/Lateromedial) p. 246-‐249


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10” crosswise; Tabletop; Non-‐grid •  Pa%ent-‐ lateral recumbent; separate affected toe •  Part-‐ (1st-‐2nd digits) place on unaffected side; toe in true

lateral; (3rd-‐5th digits) place on affected side; toes in true lateral; support heel

•  Manipulate toes only if no deformity is apparent •  CR-‐ center through IP joint of hallux or PIP joints •  Sheld Gonads


Structures Shown •  Lateral projec%on of the phalanges •  IP ar%cula%ons projected free of other toes


Evalua%on Criteria •  Proper collima%on •  Phalanges in profile (toenails lateral) •  Phalanx without superimposi%on of toes (at least show

proximal phalanx) •  Open IP joint spaces; MTP joints overlap •  So\ %ssue & bony trabecular detail

Sesamoids: Tangen%al-‐ Lewis Method p. 250-‐251


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10” crosswise; Tabletop; Non-‐grid •  Pa%ent-‐ prone on table; elevate ankle for stability •  Part-‐ dorsiflex foot & rest toe on table; ball of foot

perpendicular to horizontal plane; center IR to 2nd metatarsal •  CR-‐ perpendicular & tangen%al to 1st MTP •  Sheld Gonads


Structures Shown •  Tangen%al projec%on of metatarsal head in profile •  Sesamoid bones


Evalua%on Criteria •  Sesamoids free of any por%on of the 1st metatarsal •  Metatarsal heads

Sesamoids: Tangen%al-‐ Holly Method p. 250-‐251


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10” crosswise; Tabletop; Non-‐grid •  Pa%ent-‐ seated on table; foot dorsiflexed •  Part-‐ medial border is ver%cal; plantar surface at 75° of IR;

hold toes in flexed posi%on with gauze •  CR-‐ perpendicular to head of 1st metatarsal •  Sheld Gonads


Structures Shown •  Tangen%al projec%on of metatarsal head in profile •  Sesamoid bones


Evalua%on Criteria •  Sesamoids free of any por%on of the 1st metatarsal •  Metatarsal heads

Foot: AP Axial-‐ Dorsoplantar p. 252-‐255


•  kVp-‐ 65-‐75 •  SID-‐ 38” •  IR-‐ 8”x10” crosswise; Tabletop; Non-‐grid •  Pa%ent-‐ supine or seated on table; flex knee •  Part-‐ center IR to base of 3rd metatarsal; rest en%re plantar

surface on IR; •  CR-‐ 10° toward heel entering base of 3rd metatarsal •  Angle-‐ 10° cephalic •  Sheld Gonads


Structures Shown •  AP projec%on of tarsals anterior to talus, metatarsals, &

phalanges •  Used for localizing foreign bodies & determine the loca%on of

fragments in fractures of the metatarsals & anterior tarsals, & for performing general surveys of the bones of the foot


Evalua%on Criteria •  Proper collima%on •  No rota%on of foot •  Equal space between the adjacent midsha\s of 2nd through

4th metatarsals •  Overlap of the 2nd through 5th metatarsals •  Visualiza%on of the phalanges & tarsals distal to talus &

metatarsals •  Open joint spaces between medial & intermediate cuneiforms

Foot: AP Oblique-‐ Medial Rota%on p. 256-‐257


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 10”x12” lengthwise; Tabletop; Non-‐grid •  Pa%ent-‐ supine or seated on table; flex knee •  Part-‐ IR under foot; rotate leg medially; plantar surface 30°

from IR (or lateral cuneiform is thrown over other cuneiforms)

•  CR-‐ perpendicular to base of 3rd metatarsal •  Sheld Gonads


Structures Shown •  Shows interspaces between: cuboid & calcaneus, cuboid &

4th/5th metatarsals, cuboid & lateral cuneiform, & talus & navicular

•  Cuboid in profile •  Sinus tarsi


Evalua%on Criteria •  Proper collima%on •  3rd-‐5th metatarsals free of superimposi%on •  Lateral tarsals with less superimposi%on than AP •  Lateral TMT & intertarsal joints •  Sinus tarsi •  Tuberosity of 5th metatarsal •  Bases of 1st & 2nd metatarsals superimposed on medial &

intermediate cuneiforms •  Equal space between sha\s of 2nd-‐5th metatarsals •  Sufficient density to show phalanges, metatarsals, & tarsals

Foot: AP Oblique-‐ Lateral Rota%on p. 258-‐259


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 10”x12” lengthwise; Tabletop; Non-‐grid •  Pa%ent-‐ supine on table; flex knee •  Part-‐ IR under foot; rotate leg lateral so plantar surface is 30°

from IR •  CR-‐ perpendicular to base of 3rd metatarsal •  Sheld Gonads


Structures Shown •  Interspaces between the 1st & 2nd metatarsals •  Space between the medial & intermediate cuneiforms


Evalua%on Criteria •  Separate 1st & 2nd metatarsal bases •  No superimposi%on of medial & intermediate cuneiforms •  Navicular bone more clear than in medial rota%on •  Sufficient density to show phalanges, metatarsals, & tarsals

Foot: Mediolateral p. 260


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 10”x12” lengthwise; Tabletop; Non-‐grid •  Pa%ent-‐ lateral recumbent to affected side; leg & foot lateral;

place opposite leg behind affected leg •  Part-‐ elevate & support knee; plantar surface perpendicular

to IR; center IR midfoot; dorsiflex foot to 90° •  CR-‐ perpendicular to base of 3rd metatarsal •  Sheld Gonads


Structures Shown •  En%re foot in profile •  Ankle joint •  Distal ends of %bia & fibula


Evalua%on Criteria •  Evidence of proper collima%on •  Metatarsals nearly superimposed •  Distal leg •  Fibula overlapping posterior por%on of %bia •  Tibiotalar joint •  Sufficient density to show superimposed tarsals & metatarsals

Foot: Lateromedial

Foot: Lateromedial

•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 10”x12” lengthwise; Tabletop; Non-‐grid •  Pa%ent-‐ lateral recumbent on unaffected side •  Part-‐ dorsiflex foot to 90°; support knee; •  CR-‐ perpendicular to base of 3rd metatarsal •  Gives true lateral •  Sheld Gonads

Foot: Lateromedial

Structures Shown •  En%re foot in profile •  Ankle joint •  Distal ends of %bia & fibula

Foot: Lateromedial

Evalua%on Criteria •  Evidence of proper collima%on •  Metatarsals superimposed •  Distal leg •  Fibula overlapping posterior por%on of %bia •  Sufficient density to show superimposed tarsals & metatarsals

Longitudinal Arch: Lateral-‐ Weight Bearing p. 262


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 10”x12” lengthwise; Tabletop; Non-‐grid •  Pa%ent-‐ upright in natural posi%on; elevate feet to level of

tube; may need to use mobile unit •  Part-‐ place IR in groove or between blocks; one foot on either

side of IR; weight distributed equally; center IR to base of 3rd metatarsal; a\er exposure replace IR to do other foot

•  CR-‐ perpendicular to point just above base of 3rd metatarsal •  Sheld Gonads


Structures Shown •  Lateromedial projec%on of bones of foot with weight-‐bearing •  Used to show structural status of the longitudinal arch •  Right & le\ sides are examined for comparison


Evalua%on Criteria •  Superimposed plantar surfaces of metatarsal heads •  En%re foot & distal leg •  Fibula overlapping the posterior por%on of %bia •  Sufficient density to visualize superimposed tarsals &

metatarsals

Longitudinal Arch: AP Axial-‐ Weight Bearing p. 264


•  kVp-‐ 65-‐75 •  SID-‐ 38” •  IR-‐ 10”x12” lengthwise; Tabletop; Non-‐grid •  Pa%ent-‐ standing-‐upright posi%on •  Part-‐ stand with both feet on IR; mark both sides; weight

distributed evenly; may hold tube for stability •  CR-‐ 10° toward heel; posi%oned between feet at level of base

of 3rd metatarsal •  Angle-‐ 10° towards heel •  Sheld Gonads


Structures Shown •  Weight-‐bearing AP axial of both feet to permit accurate

evalua%on/comparison of the tarsals & metatarsals


Evalua%on Criteria •  Both feet centered on one image •  Phalanges, metatarsals, & distal tarsals •  Correct right & le\ marker placement & weight-‐bearing

marker •  Correct exposure technique to visualize all components

Calcaneus: Axial-‐ Plantodorsal p. 271


•  kVp-‐ 65-‐75 •  SID-‐ 32” •  IR-‐ 8”x10”; Tabletop; Non-‐grid •  Pa%ent-‐ supine or seated on table; legs fully extended •  Part-‐ center IR to midline of ankle; hold foot dorsiflexed with

gauze; if ankle can’t be dorsiflexed enough: elevate foot •  CR-‐ enters base of 3rd metatarsal; directed to midpoint of IR

at cephalic 40° angle •  Angle-‐ 40° cephalic •  Sheld Gonads


Structures Shown •  Axial projec%on of calcaneus


Evalua%on Criteria •  Proper collima%on •  Calcaneus & subtalar joint •  No rota%on of calcaneus-‐ 1st & 5th metatarsals not projected

to sides of foot •  Anterior por%on of calcaneus without excessive density over

posterior por%on, or 2 images may be needed for 2 regions of thickness

Calcaneus: Axial-‐ Dorsoplantar p. 272-‐273


•  kVp-‐ 65-‐75 •  SID-‐ 32” •  IR-‐ 8”x10”; Tabletop; Non-‐grid •  Pa%ent-‐ prone on table •  Part-‐ elevate ankle; dorsiflex foot to perpendicular to table; IR

against plantar surface •  CR-‐ dorsal surface of ankle joint directed to center of IR at 40°

caudally •  Angle-‐ 40° caudal •  Sheld Gonads


Structures Shown •  Axial projec%on of calcaneus & subtalar joint •  CT is o\en used


Evalua%on Criteria •  Calcaneus & subtalar joint •  Sustentaculum tali •  Calcaneus not rotated-‐ 1st or 5th metatarsals not projected to

sides of foot •  Anterior por%on of calcaneus without excessive density over

posterior por%on; may need 2 images for 2 regions of thickness

Calcaneus: Lateral-‐ Mediolateral p. 274


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10”; Tabletop; Non-‐grid •  Pa%ent-‐ lateral recumbent on affected side; support knee •  Part-‐ adjust calcaneus to center of IR •  CR-‐ perpendicular to calcaneus; center 1” distal to medial

malleolus at subtalar joint •  Sheld Gonads


Structures Shown •  Ankle joint & calcaneus in lateral profile


Evalua%on Criteria •  Proper collima%on •  No rota%on of calcaneus •  Density of sustentaculum tali, lateral tuberosity, & so\ %ssue •  Sinus tarsi •  Ankle joint & adjacent tarsals

Ankle: AP p. 279

Ankle: AP p. 279

•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10” or 10”x12” for bilateral; Tabletop; Non-‐grid •  Pa%ent-‐ supine or seated with affected limb extended •  Part-‐ flex ankle & foot in ver%cal posi%on •  CR-‐ perpendicular though ankle joint midway between

malleoli •  Sheld Gonads

Ankle: AP p. 279

Structures Shown •  AP projec%on of ankle joint •  Distal ends of %bia & fibula •  Proximal por%on of talus

Ankle: AP p. 279

Evalua%on Criteria •  Proper collima%on •  Tibiotalar joint space •  Ankle joint centered to exposure area •  Normal overlap of %biofibular joint with anterior tubercle

slightly superimposed over fibula •  Talus slightly overlapping distal fibula •  No overlapping of medial talomalleolar ar%cula%on •  Medial & lateral malleoli •  Talus with proper density •  So\ %ssue

Ankle: Lateral-‐ Mediolateral p. 280


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10”; Tabletop; Non-‐grid •  Pa%ent-‐ lateral recumbent on affected side un%l ankle is

lateral •  Part-‐ center IR to ankle joint; lateral surface touching IR;

dorsiflex foot to prevent lateral rota%on of ankle •  CR-‐ perpendicular to ankle joint entering medial malleolus •  Sheld Gonads


Structures Shown •  True lateral projec%on of lower 3rd of %bia & fibula •  Ankle joint •  Tarsals-‐ including base of 5th metatarsal


Evalua%on Criteria •  Proper collima%on •  Ankle joint centered to exposure area •  Tibiotalar joint well visualized with medial & lateral talar

domes superimposed •  Fibula over posterior ½ of %bia •  Distal %bia & fibula, talus, & adjacent tarsals •  5th metatarsal seen to check for Jones fracture •  Density sufficient to see outline of distal por%on of fibula

Ankle: Lateral-‐ Lateromedial p. 282


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10”; Tabletop; Non-‐grid •  Pa%ent-‐ lateral recumbent on affected side; extended leg

placed laterally •  Part-‐ center IR to ankle; foot in lateral posi%on; patella

perpendicular to table; support knee if needed •  CR-‐ perpendicular through ankle joint entering ½” superior to

lateral malleolus •  Sheld Gonads


Structures Shown •  Lateral projec%on of lower 3rd of %bia & fibula, ankle joint, &

tarsals


Evalua%on Criteria •  Ankle joint centered to exposure area •  Tibiotalar joint well visualized with medial & lateral talar

domes superimposed •  Fibula over posterior ½ of %bia •  Distal %bia & fibula, talus, & adjacent tarsals •  Density sufficient to see outline of distal por%on of fibula

Ankle: AP Oblique-‐ Medial p. 283


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10” or 10”x12” for bilateral; Tabletop; Non-‐grid •  Pa%ent-‐ supine or seated with leg extended •  Part-‐ center IR to ankle between malleoli; dorsiflex foot to

90°; rotate leg & foot 45° •  CR-‐ perpendicular to ankle joint entering midway between

malleoli •  Sheld Gonads


Structures Shown •  Distal ends of %bia & fibula-‐ o\en superimposed over talus •  Tibiofibular ar%cula%on


Evalua%on Criteria •  Proper collima%on •  Distal %bia, fibula, & talus •  Distal %bia & fibula overlap some of talus •  Talus & distal %bia & fibula adequately penetrated •  Tibiofibular ar%cula%on

Ankle Mor%se: AP Oblique-‐ Medial p. 284-‐285


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10” or 10”x12” for bilateral; Tabletop; Non-‐grid •  Pa%ent-‐ supine or seated on table •  Part-‐ center ankle joint to IR; rotate leg & foot 15°-‐20°

internally un%l intermalleolar plane is parallel with IR; plantar surface at right angle to leg

•  CR-‐ perpendicular entering ankle joint midway between malleoli

•  Sheld Gonads


Structures Shown •  En%re ankle mor%se joint in profile •  All 3 sides of mor%se joint should be visualized


Evalua%on Criteria •  Proper collima%on •  En%re ankle mor%se joint •  No overlap of anterior tubercle of %bia & superolateral

por%on of talus with fibula •  Talofibular joint space in profile •  Talus shown with proper density

Ankle: AP Oblique-‐ Lateral p. 286


•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10”; Tabletop; Non-‐grid •  Pa%ent-‐ seated on table with leg extended •  Part-‐ plantar surface in ver%cal posi%on; laterally rotate leg &

foot 45°; center ankle joint to IR •  CR-‐ enter ankle joint midway between malleoli •  Sheld Gonads


Structures Shown •  Useful for determining fractures & showing superior aspect of

calcaneus


Evalua%on Criteria •  Subtalar joint •  Calcaneal sulcus (superior por%on of calcaneus)

Ankle: AP-‐ Stress Views p. 287

Ankle: AP-‐ Stress Views p. 287

•  kVp-‐ 65-‐75 •  SID-‐ 40” •  IR-‐ 8”x10”; Tabletop; Non-‐grid •  Pa%ent-‐ supine or seated on table with leg extended •  Part-‐ hold foot in extreme stress with strap; turn foot forcibly

toward opposite side •  CR-‐ perpendicular to ankle; enters midway between malleoli •  Sheld Gonads

foot & ankle positioning

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