Wrist and Hand Imaging Flashcards
Primary ossification center of MC and phalangeal shafts begins at
8 wks gestation
Shafts are fully formed at birth
No ossification in carpals seen when
Newborn - 5 or 6 months
Ossification centers of capitate and hamate appear at
6 months
MCs and radius have secondary ossification centers by
1 year
Triquetrum center ossification is visible by when
2 years
Secondary ossificiation centers of ulna appear when
by 5 years
All carpal bones except pisiforma are visible on xray when
by 6 years
9-13 years - the secondary ossification centers of the phalanges are
Wider than the shafts
Capral bones are in their adult shapes
All seondary ossification centers should be present at
14 years F
16 years M
Routine projections
PA
Lateral
Oblique - often added to complete the series
PA projection - position
hand as flat as possible with palmar aspect closest to the film
Thumb in oblique position
PA projection - what is the longest
Proximal phalanges
What is in line with the long axis of the radius
Long axis of the 2nd MC
Where should you be able to draw a ling
Along distal articulating surfaces of the 3-5 MCs
MC fx - common where
3rd and 4th - known as a boxers or brawlers fracture
Thumb - sesamoid bones
2 of them at the MC head
What inserts onto the sesamoid bones
Adductor pollicis - the ulnar one
Flexor pollicis brevis - radial one
Sesamoid bones lie within the
palmar plate
close to origin of the tunnel for FPB
What can cause fx to sesamoid bones
Severe hyperextension trauma - is probably more likely to rupture palmar plate and associated ligaments
Can develop hematoma through FPB
Most commonly fractured carpal bone
Scaphoid
Scaphoid is usually fractured where
at midpoint
Kienbocks disease
Avascular necrosis of lunate - often without history of trauma
Sesamoid within the flexor carpi ulnaris
Pisiform
overlaps triquetrum on PA
Trapezium is superimposed with
Trapezoid
Injury to trapezium
Rare - almost always collateral to injury of other wrist structures
Capitate isolated injury
Rare
Hamate fracture
Uncommon but should be considered if pt is involved in activities with clubs or bats
Fracture of distal radius ___% of all skeletal fx
16%
Alignment - carpal arches
Gilulas lines
1st line - carpal arches - formed by
Proximal convex surfaces of scaphoid, lunate, and triquetrum
2nd line - carpal arches - formed by
Distal concave surfaces of the same bones
3rd line - carpal arches - formed by
proximal convex curves of capitate and hamate
Ulnar variance
Difference between the length of ulna and radius
Should be less than or equal to 1.0 mm
Positive ulnar variance - defined as ulna being
more than 1 mm distal to the radius
Positive ulnar variance occurs with
age, secondary to degenerative changes in fibrocartilaginous disc
Positive ulnar variance is associated with
ulnar impact fracture and lunotriquetral ligament disruption
Positive ulnar variance is commonly seen in
gymnasts secondary to stress on radial growth plates
Negative ulnar variance - define
ulna is shortened compared to the radius
Negative ulnar variance - commonly seen in
Kienbocks disease
Kienbocks disease
Osteonecrosis of the lunate
Lateral view - best for determining what
displacements of long bones in hand and carpals
Lateral view - what is resting on the receptor
Ulnar border of hand
Lateral view - central ray moves from
Radial to ulnar
Lateral view - what is magnified and why
Thumb - because of distance from the receptor
Lateral view shows what view of thumb and what view of other fingers
Posterolateral of thumb
Lateral of rest of hand and wrist
Lateral view - most bones are
superimposed
but can still identify displacement
Volar tilt - angle formed between
A line connecting distal points of the volar and dorsal rim of the radius
A second line perpendicular to the long axis of the radius
