Radiographic Evaluation of HAV Flashcards
should radiographs for evaluating HAV be done WB or NWB?
WB
how is the hallux interphalangeus angle measured?
angle formed by the longitudinal bisection of proximal phalanx and distal phalanx of the hallux
what is the normal hallux interphalangeus angle?
less than 10 deg
how is the hallux abductus angle measured?
angle formed by the bisection of the long axis of the proximal phalanx and 1st met
what is the normal hallux abductus angle?
less than 15 deg
how is DASA measured?
angle formed by the long bisection of the proximal phalanx and the line perpendicular to the line formed by marking cartilage of the base of proximal phalanx
what is the normal DASA?
0-8 deg
what does DASA tell you?
looks at angular deviation of the cartilage at base of proximal phalanx
how is PASA measured?
angle formed by line perpendicular to long bisection of 1st met and a line formed by marking 1st met head cartilage
what does PASA tell you?
evaluates position of articular cartilage of 1st met head
what is normal PASA?
0-8 deg
how is IM angle measured?
angle formed by the longitudinal bisection of 1st met and 2nd met
what is normal IM angle?
0-10 deg
what is considered a mild-moderate deformity?
10-15 deg
what is considered a severe deformity?
> 15 deg
what surgical approach would you use to correct a severe deformity (>15IMA)?
perform procedures more proximally at the base of the met
what surgical approach would you use to correct a mild-moderate deformity (IMA is 10-15 deg)?
distal metatarsal osteotomy
how is the metatarsus adductus angle measured?
angle formed by line perpendicular to midfoot bisection and long bisection of 2nd met
name the 4 points used to create midfoot bisection for metatarsus adductus angle.
1st met-cuneiform joint
talonavicular joint
calcaneal-cuboid joint
4th met-cuboid joint (or 5th met)
list the reference values indicating severity of metatarsus adductus angle.
0-15 deg: normal
16-25 deg: mild
26-35 deg: moderate
>35 deg: severe
what is an alternate way to measure bisection of midfoot needed for metatarsus adductus angle?
angle formed by bisections of intermediate cuneiform and 2nd met
*this overestimates the angle by 5-10 deg though
how do you calculate the true IM angle of a patient with metatarsus adductus angle > 15 deg?
(# of met met adductus - 15) + IM
how do you evaluate joint positions?
draw a line on articular surface of 1st met head and on proximal phalanx
how is a congruous joint described?
articulating lines are parallel
how is a deviated joint described?
lines intersect outside the joint
how is a subluxed joint described?
lines intersect inside the joint
if PASA + DASA = HAA how would you classify this HAV deformity? describe the joint in this situation.
structural deformity
*joint is congruent
PASA/DASA abnormal
if PASA + DASA is less than HAA, how would you classify this HAV deformity? describe the joint in this situation.
positional deformity
*joint is deviated/ subluxed
PASA/DASA normal
if PASA + DASA is greater than HAA, how would you classify this HAV deformity? describe the joint in this situation.
combined deformity
*joint is deviated /subluxed
PASA/DASA abnormal
which shape of metatarsal head is most unstable?
round head
which shape of metatarsal head is most stable?
square w/ ridge
how is metatarsal protrusion distance measured?
bisect 1st and 2nd met; draw their respective arches. the distance btwn the 2 should be about 2mm.
what is normal metatarsal protrusion distance?
+/- 2mm
what does metatarsal protrusion distance tell you?
if 1st met is short or long
(+) indicates long 1st met
(-) indicates short 1st met
how do you measure tibial sesamoid position?
relationship of the tibial sesamoid to the bisection of the 1st metatarsal shaft
what is the normal positions for tibial sesamoid?
positions 1,2,3
what is the abnormal positions of tibial sesamoid?
positions 4-7
what is tibial sesamoid position used for?
indication for removal of fibular sesamoid
what can you look for on a lateral view radiograph?
1st ray elevation
hammer toes
hallux crossing over second
