2a. Wrist Flashcards
where is the trapezium carpal bone
under thumb
which of the 3 carpal bones starting with T are proximal and which are distal
distal = trapezium and trapezoid proximal = triquetrum
in a lateral view what is the orientation of the scaphoid, lunate and capititate
captitate is vase most distally
lunate is cup in middle
scaphoid is bean/cup at the most distal
in the lateral view of the wrist the palmar cortex of the pisiform bone should be where in the scaphoid pole
in the centre of the distal scaphoid pole
what is the zone of vulnerability
area most likely to be injured in the carpal bone area of the wrist
what are the 2 fat pads in the wrist of interest to us
pronator quadratus and scaphoid fat stripe
what are the 3 things that the pronator quadratus can appear as apart from normal
raised, disrupted and obliterated
how do the fat stripes look in images compared to muscle and bone
fat is slightly more translucent than muscle
when bleeding around joint what can happen to the fat stripes
can be lifted disrupted or obliterated
what can happen to the scaphoid stripe
can be obliterated
what are the carpal arcs
what are they good for
proximal and distal rows of carpal bones each of their sets of arcs
good for subtle mal-alignments
and 3 carpal bones can undergo fractures and dislocation
scaphoid
lunate
triquetrum
what is the mechanism of scaphoid fractures
FOOSH
usually pinched because of falling on it or direct blow
what are the 4 locations for scaphoid fractures
what are the order of common to least common
distal, waist, proximal and tubercle
waist>proximal>distal>tubercle
what is the scaphoid blood supply
scaphoid has retrograde blood supply to the proximal end
what happens if there is a distal or proximal scaphoid fracture in terms of blood supply
distal fracture still got a bit of blood supply
proximal = may be okay
what happens if there is a waist scaphoid fracture in terms of blood supply
almost certain to lose whole of proximal end
what does dead bone look like on xray from avascular necrosis scaphoid fracture
brighter area is dead as it is more dense than bone
what are the 3 types of lunate injuries
lunate dislocation
peri-lunate dislocation
scapho-lunate dissociation
what happens in a scapho-lunate dissociation
over time gap between lunate and scaphoid gets wider and capitate pushes through
what is a perilunate dislocation caused by
high energy injury
what does a perilunate dislocation look like
radius and lunate stay in contact - not dislocated -
capitate and all other carpal bones dislocated usually dorsally
what happens to the shape of the lunate carpal bone in a perilunate dislocation
shape changes to piece of pizza/pie triangle shape
which direction is the capitate and carpal bones most likely to dislocated in a perilunate dislocation
dorsally/posteriorly
