Chapter 4 : Wrist Flashcards
is the thumb on the lateral or medial aspect
Lateral
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
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
for a pa wrist where is limited superimposition
Superimposition of the MC bases is limited
criteria for pa wrist:
Radial and ulnar styloids are at the extreme lateral and medial edges
*Radioulnar articulation is open
*Superimposition of the MC bases is limited
*Rotation is controlled by the position of the hand, elbow, and humerus
*Carpal bones in center, ¼ of distal ulna and radius plus ½ of the proximal MC are included in the field
what better demonstrates the ulna in a pa wrist
when the humerus, elbow, and forearm are in the same plane 90degrees
what type of fracture is the styloid process likely to get
an avulsion fracture
what type of fracture happens when there is hyperextension or hyperflexion of a joint
avulsion
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 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
causes the laterally located carpal bones and MC bases to be superimposed and increases visibility of the pisiform and hamate hoo
Internal rotation of the hand and wrist
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
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 brings the ulnar styloid in profile
Abduction the humerus to position the elbow in the lateral position and humeral epicondyles aligned perpendicular to IR
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
if posterior radial margin is 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 distal to the posterior margin how was the proximal forearm positioned
if anterior radial margin is distal to the posterior margin 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
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
A patient with a thick or muscular proximal forearm it may be necessary to extend the arm off the IR or table in order to position it parallel with the IR
how to put the wrist in a neutral position
To put the wrist in a neutral position, flex the patient’s 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
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 lunat
Extension (hand extended up)
-pullinh distal part of scaphoid up elongating it
Excessive foreshortening and signet ring configuration of scaphoidLunate is triangular3rd -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 MCClosed 2nd-3rd CM joint spacesDecreased scaphoid foreshortening*Triangular lunate
wrist extension
distal scaphoid to shift anteriorly (towards palmar surface) and increase foreshortening as if forms the signet ring configuratio
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
Ulnar deviation
how will the lunate shift in ulnar deviation
Lunate will shift laterally towards the radius
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
criteria for pa oblique projection of the wrist
Contrast and density to demonstrate scaphoid fat stripe
*45 degree external oblique
*Trapezoid and trapezium are demonstrated without superposition
*Trapeziotrapezoidal joint space is open
*Scaphoid tuberosity and waist are demonstrated in profile
*Small degree of trapezoid and capitate superposition is present
if under-rotated for an oblique wrist how is the trapezoid and trapezium
If under rotated the trapezoid and trapezium are superimposed
how is trapeziotrapezoida joint space when the wrist is under rotated for an oblique
The trapeziotrapezoidal joint space is obscured
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 and positions the scaphoid directly next to the radius
radial deviation
decreases scaphoid foreshortening, the scaphoid will be elongated
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
criteria for a lateral wrist
Contrast and density to adequately demonstrate the pronator fat stripe and posterior soft tissueElbow flexed 90°and abduct humerus until it is parallel with the IRDistal scaphoid and pisiform are alignedLong axis of the 1st MC is aligned parallel with the forearm¼ distal ulna and radius and ½ proximal MC
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 is the rotation if the radius is going to the lateral
external rotation
how is the pisiform when the wrist is externally rotated
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
is this internally or externally rotated
If wrist is rotated externally (supinated) the distal scaphoid is visible posterior to the pisiformIf the distal scaphoid and pisiform are not superimposed and the ulna is positioned anterior to the radius
it is externally rotated
the pisiform , 5th digit and ulna will be anterior when there is internal or external rotation?
external rotation
if this happens is this internal or external rotation for a lateral wrist ?
the distal scaphoid is visible anterior to the pisiform
wrist is rotated internally( hand pronated)
If distal scaphoid and pisiform are not superimposed and the ulna is positioned posterior to the radius
was the wrist internally or externally rotated for a lateral wrist
the wrist was internally rotated
if the radius, scaphoid, and 2nd digit is going anterior then is this internal or external rotation of a lateral wrist
internal rotation
when the proximal forearm is higher in a lateral wrist is this radial flexion or extension
radial flexion
- align the long axis of the 3rd MC with the midforearm parallel with the IR
neutral lateral wrist
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
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
wrist flexion
wrist extension or flexion? the lunate and distal scaphoid tilt posteriorly
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
is this radial deviation or ulnar?
foreshortened scaphoid will go down anterior pushing pisiform distally
radial deviation
*if the first MC is not lowered it will be foreshortened and its proximal aspect is superimposed over what carpal bone?
trapezium
*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?
scaphoid
what area on the scaphoid is the most common spot to be fractured
the waist of the scaphoid
what angle best demonstrates the proximal scaphoid
5 to 10 degress
what degree best demonstrates the waist of the scaphoid
15 degrees
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 do you need when the fracture is more distal on the scaphoid
less degree
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
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
-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
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
