Chapter 4: Wrist Flashcards
is the thumb on the lateral or medial aspect
Lateral (radius side)
what is at the extreme lateral and medial edges of the radius and ulna
Radial and ulnar styloids are at the extreme lateral and medial edges keep it in the same plane
what articulation should be open in a pa wrist
Radioulnar articulation is open
what is rotation controlled by for a pa wrist
hand, elbow, and humerus keep in the same plane
for a pa wrist where is limited superimposition
Superimposition of the MCP bases is limited
what better demonstrates the ulna styloid process in a pa wrist
when the humerus, elbow, and forearm are in the same plane 90 degrees
what type of fracture is the ulnar styloid process likely to get
an avulsion fracture
what type of fracture happens when there is hyperextension or hyperflexion of a joint
avulsion
What do you do to bring the carpal bones closer for PA wrist
curl fingers up to bring carpal bones in contact with IR
What’s the CR for PA wrist
CR Perpendicular to midcaarpal area or carpal bones
What should you make sure you get for PA wrist
make sure you get up to McP bases up to radius / ulna
What should be visible on all PA wrist images
Scaphoid fat stripe
what is adequate to demonstrate the schaphoid fat stripe
contrast and density
It is convex and located lateral to the scaphoid in an uninjured wrist
scaphoid fat stripe
A change in the covexity may indicate the presence of a…
joint effusion
radial side fracture of the scaphoid radial styloid process
or proximal first metacarpal
how should the scaphoid fat pad be?
Convexed
How much should you get for carpal bones, radius/ ulna, and proximal MCP for PA wrist
carpal bones in center 1/4 of distal ulna and radius plus 1/2 of the proximal MCP are included in the field
what projection shows better carpal interspaces
AP wrist
fluid can buldge out
joint effusion
can die off when there is a fracture
scaphoid
how are the hand and wrist rotated in this oblique position?:
the MC bases and carpal bones on the medial aspect of the wrist are superimposed( whereas laterally they are not)
Hand and wrist rotated externally into an oblique position
what wrist rotation best demonstrates the trapezium and trapzoid.
decreased space between 4th and 5th MCP
- Radioulnar articulation closes
external rotation of wrist
causes the laterally located carpal bones and MC bases to be superimposed and increases visibility of the pisiform and hamate hook
- radioulnar atriculation close
Internal rotation of the hand and wrist
What should you look for to see if there’s a rotation of the wrist
Look at the 3rd MCP to see if is straight or not
away from the body
abduction
towards the midline of the body
adduction
what determines the positioning of the placement of the ulnar styloid
humerus and elbow
what happens if the humerus remains in a vertical position
If humerus remain in a vertical position the ulna and radius cross over and the ulnar styloid is no longer in profile
when elbow is bent at 90 degrees what is in profile
the ulna styloid process
Abduction the humerus to position the elbow in the lateral position and humeral epicondyles aligned perpendicular to IR
brings the ulna styloid process in profile
what are parallel with each other
radius and ulna
what type of rotation is it when the pisiform is out by itself
internal rotation
what MC should you be looking at if you are concerned if there is rotation
the third MC- it should be straight
what is concave and slants 11 degrees from posterior to anterior
Distal radial carpal articular surface
how many degrees does the distal radial carpal surface concave and slant from posterior to anterior
11 degrees
CR perpendicular Forearm is positioned parallel with IR for PA wrist, the slant of the distal radius causes the
regular x-ray
the posterior radial margin to project slightly distal to the anterior radial margin obscuring the radiocarpal joints
when the radius is straight out
the posterior and anterior aspect do not superimposed each other
if posterior radial margin is extremely distal to the anterior margin , how was the proximal forearm
the proximal forearm was elevated higher than the distal forearm ( elbow was raised)
if anterior radial margin is extremely distal to the posterior margin how was the proximal forearm positioned
the proximal forearm was positioned lower than distal forearm (elbow lowered)
what would you do to superimpose the distal radial margins and demonstrate the radioscaphoid and radiolunate joints as open spaces
- posterior aspect towards proximal
- anterior aspect more distal
the proximal aspect of the forearm should be positioned slightly lower than the distal forearm(5 to 6 degrees)
(so half of the 11 degrees)
what should you do when you have a thick or muscular forearm
proximal forearm it may be necessary to extend the arm off the IR or table in order to position it parallel with the IR
- lower proximal forearm parallel with IR
how to put the wrist in a neutral position
To put the wrist in a neutral position, flex the patient’s fingers (curl fingers), flexing the until the MC are angled to 10-15 degrees with the IR
results in obscured 3rd -5thCM joint spaces and severely foreshortened scaphoid (signet ring configuration) and triangular lunate
distal portion goes anterior
Flexion
-fingers are straight out
when there is foreshortening of the schaphoid what is visible
visible signet ring (white circle)
results in foreshortened MC and closed 2nd-3rd CM joint spaces , decreased scaphoid foreshortening, and triangular lunate
scaphoid elongating
Extension (hand extended up)
-pullinh distal part of scaphoid up elongating it
Excessive foreshortening and signet ring configuration of scaphoid
- Lunate is triangular
- 3rd -5th CM places are obscured
wrist flexion
what can you do to fix the wrist flexion
The hand needs to be extended*Curl the patient’s finger
Foreshortened MCP Closed 2nd-3rd CMC joint spaces
- Decreased scaphoid foreshortening
- brought fifngers up
- elongated scaphoid
- triangular lunate
- bases of the metacarpals are obscuring distal row of carpal bones
wrist extension
distal scaphoid to shift anteriorly (towards palmar surface) and increase foreshortening as if forms the signet ring configuration
- hand towards thumb
- lunate will shift medially towards ulna
- ring (flexion)
radial deviation
how will the lunate shift in a radial deviation
Lunate will shift medially toward the ulna
distal scaphoid tilts posteriorly (dorsally) and demonstrate decrease foreshortening
- elongate scaphoid
- lunate will shift laterally towards the radius
ulnar deviation
why is ulnar deviation or radial deviation typically done
for wrist joint mobility
what is ulnar deviation used for
to demonstrate the scaphoid better - elongates it
Note the long axis of the 3rd MCP, use to judge
if foreshortening is due to flexion or extension of carpal bones or radial and/or ulnar deviation
make sure make sure you have contrast and density
to demonstrate scaphoid fat stripe
PA oblique projection is how many degrres
45 degrees oblique
What is best demonstrated in a PA 0blique wrist
trapezoid and trapezium are demonstrated without superimposition
what joint space is open for a PA oblique wrist
Trapeziotrapezoidal joint
What is demonstrated in profile for a PA oblique wrist
Scaphoid tuberosity and waist
Small degree of trapezoid and capitate superposition is present
- slight space between 4th and 5th MCP joint
- lateral aspect is best demonstrated
- lower thumb to not foreshroten it and not obscure trapezium
PA oblique wrist
if under-rotated for an oblique wrist how is the trapezoid and trapezium
If under rotated the trapezoid and trapezium are superimposed
how is trapeziotrapezoidal joint space when the wrist is under rotated for an oblique
The trapeziotrapezoidal joint space is obscured
The trapezoid demonstrates minimal capitate superimposition
under rotated pa oblique wrist
The long axis of the 3rdmetacarpal and midforearm are aligned long axis of the collimation field, what position is the wrist in
the wrist is in a neutral position.
does radial or unlar deviation increase the foreshortening of the scaphoid
radial deviation
Preventing visualization of the scaphoid tuberosity and waist
radial deviation
positions the scaphoid directly next to the radius
decreases scaphoid foreshortening, the scaphoid will be elongated
ulnar deviation
the MCP is not aligned with the midforearm
ulnar deviation
in a oblique wrist *If the image demonstrates the posterior radial margin too far distal to the anterior margin , how was the proximal forearm
the proximal forearm was elevated higher than the distal forearm
in an oblique wrist , If the anterior radial margin is demonstrated distal to the posterior margin, how is the proximal forearm
the proximal forearm was positioned lower than the distal forearm
Parallel to the anteriorsurface of the distal radiusNormally convexBowing or obliteration mayIndicate subtle radial fracture
pronator fat stripe
scaphoid and lunate articulate with
radius
anterior margain is more than the posterior for radius
11 degrees difference in the radius
more whiter
an open radiolunate and radioscaphoid joint spaces
the proximal forearm was positioned slightly lower 5 to 6 degrees
In a lateral wrist there should be contrast and density to adequately demonstrate the
pronator fat stripe and posterior soft tissue should look convex
if pronator fat stripe is not convex
there is a subtle radial fracture
for lateral wrist elbow should be flexed 90 degrees and abduct humerus until
it is parallel with ir
in a lateral wrist what should be aligned
distal scaphoid and pisiform
what is aligned parallel with the forearm for lateral wrist
thumb has to be down don’t want to obscure the trapezium
long axis of the 1st McP
what do you want to make sure you get for lateral wrist in relation to radius and ulna and MCp
1/4 distal of ulna and radius and 1/2 of proximal MCP
parallel to the anterior surface of the distal radius
pronator fat stripe
how to check for rotation of a lateral wrist
To detect rotation check the relationship between the distal aspect of the scaphoid and the pisiform
how should the the distal aspect of the scaphoid and the pisiform be in a lateral wrist
They should superimpose and demonstrate anterior to the capitate and lunate
criteria for lateral wrist to make sure that is no rotation
-all mc should all be superimposed
-radius and ulna superimposed
-distal scaphoid and pisiform anterior to capatate and lunate
what should be align on top of one another in a lateral wrist
pisiform and scaphoid
how is the pisiform when the wrist is externally rotated
a
bringing pisiform forward
how should the pisiform in a true lateral wrist be
scaphoid and pisiform should be superimposed
-scaphoid can be slightly anterior but pisiform superimposed over it
how is the scaphoid when the wrist is rotated externally for a lateral wrist
*If wrist is rotated externally (supinated) the distal scaphoid is visible posterior to the pisiform
5th MCP, pisiform, ulna more anterior in
external rotation of lateralwrist
pisiform will go more anterior, radius will go posterior and ulna will go anterior
external rotation of lateral hand
If the distal scaphoid and pisiform are not superimposed and the ulna is positioned anterior to the radius
it is externally rotated lateral wrist
If wrist is rotated internally( hand pronated)
the distal scaphoid is visible anterior to the pisiform
in an internal rotation of the lateral wrisyt
pisiform will go posterior the scaphoid more anterior radius will go anterior and ulna posterior
If distal scaphoid and pisiform are not superimposed and the ulna is positioned posterior to the radius,
the wrist was internally rotated
scaphoid, radius, 2nd MCP more anterior
internal rotation of lateral wrist
if the radial side is placed on the IR
the ulna and pisiform are anterior to the radius and scaphoid
align the long axis of the 3rd MC with the midforearm parallel with the IR
neutral lateral wrist
when the proximal forearm is higher in a lateral wrist is this radial flexion or extension
radial flexion
what view forces the distal scaphoid anteriorly and the pisiform is distal to the scaphoid
Radial deviation of wrist
what deviation shifts the distal scaphoid posteriorly
ulnar deviation
when the proximal forearm is higher it create radial flexion or radial deviation which
forces the distal scaphoid anterior and tghe pisiform more distal to the scaphoid which foreshrotens the scaphoid
The pisiform is proximal to the scaphoid
The proximal forearm may not be level ,but lower
what does this cause
ulnar deviation
is this wrist flexion or extension? the lunate and distal scaphoid tilt anteriorly
- foreshortens scaphod (ring)
wrist flexion
wrist extension or flexion? the lunate and distal scaphoid tilt posteriorly
- elongates the scaphoid
wrist extension
is the elbow is higher, is it radial or ulnar deviation
radial deviation
if the elbow is lower, is it radial or ulnar deviation
ulnar deviation
if the first MC is not lowered it will be foreshortened and its proximal aspect is superimposed over what carpal bone?
trapezium
1st and 2nd MCP should be what
at the same level
is this radial deviation or ulnar?
foreshortened scaphoid will go down anterior pushing pisiform distally
radial deviation
down from suspected fracture of scaphoid
pa axial ulnar deviation
Demonstrate scaphoid fat stripe
*Scaphotrapezium and scaphotrapezoidal joint spaces are open
*These joints are aligned at a 15° angle to the IR when the hand is fully extended
*Ulnar deviation approx. 25°
*Align 1st MC with the radius
Ulnar Deviation PA Axial Projection
the distal scaphoid tilts anteriorly approx. 20° and results in foreshortening of the scaphoid
Why does this happen
wrist is non flexed
if patient is unable to achieve max ulnar deviation what angle should you use
20 degrees
what is the most. common fractured carpal bone?
the waist of the scaphoid
what angle best demonstrates the proximal scaphoid
5 to 10 degress
what degree best demonstrates the distal scaphoid
25 degrees
where is most of the stress on when the hand is hyperexteneded
waist of the scaphoid
what degree best demonstrates the waist of the scaphoid
15 degrees
what degree do you need when the fracture is more distal on the scaphoid
more angle
If the scaphocapitate joint space is closed and the capitate and hamate are demonstrated without superimposition
how was the degree of obliquity
insufficient
If the scapholunate joint space is closed and the capitate and hamate demonstrate some degree of superimposition
how was the degree of obliquity
rotated more than needed
-tube angled inferior to superior
-tangential view skimming base of 3rd MC
-want to see arch
-good view of hamate
- hyperextend wrist til long axia of MC are close to vertical
-25-30 degree angulation
-rotate hand so 5th MC is perp to IR
Gaynor Hart
Pisiform is demonstrated without superimposition
*Hamulus of the hamate and carpal canal is clearly demonstrated
*Carpal canal is center of collimated field
*Trapezium ,distal scaphoid, pisiform and hamulus of the hamate are all included within the field
*Hyperextending (dorsiflex) of wrist until long axis of MC are close to vertical
*Central ray 25 to 30 degrees, rotate hand to the radial side approx. 10 degrees, 5th MC vertical
criteria for gaynor hart
why does this happen in a gaynor hart:
the carpal canal will not be fully demonstrated and the carpal bones will be foreshortened
angle between the CR and MC is too great
why does this happen in a gaynor hart :
the bases of the hamulus process, pisiform and scaphoid are obscured by the MC bases
angle is too small
