Chapter 4: Forearm and Humerus Flashcards
In an AP forearm how are the epicondyles
The medial and lateral epicondyles should be parallel to the IR and in profile at extreme medial and lateral edges of distal humerus
What are two other things that should be in profile for the AP forearm
The radial styloid should be in profile when arm is extended
- the radial tuberosity should be in profile medially
In an AP forearm how is the radial head
The radial head is in a slight superimposition over the lateral aspect of the ulna by about 1/4 inch
When doing the AP forearm we should use the anode heel effect what body part should be at which side
the wrist should be at the anode
- the elbow should be at the cathode side
distal forearm rotation occurs from
inaccurate positioning of the hand and wrist
For an AP forearm what should be included in the x-ray
Both joints on IR. The IR should extend one inch beyond the wrist and elbow
- make sure to get bases of metacarpals
- carpal bones
- elbow joint
What joint is partially or completely closed in an AP forearm
An partial or completely closed capitulum -radial joint due to the divergence of the beam not centered over the joint
How do you now you have rotation in AP forearm
- the radial styloid is no longer in profile 1/4 inch
- distal radius and ulna and MCP bases are superimposed
- MCP are not equal
In an internal rotation of the AP forearm what happens and what is being demonstrated
the MCP’s of the 1st and 2nd are superimposed.
- pisiform and hamate hook are better demonstrated
pisiform and hamate are better demonstrate what kind of rotation for AP forearm
internal rotation ( medial rotation) hand turned in
In an external rotation of the AP forearm what happens
the 4th and 5th MCP’s are superimposed
In a medially rotated ( internal rotation) of the forearm what will be shown
the radial head is demonstrated more or less than 1/4 superimposition on ulna
- when more than 1/4 of the head is over the ulna
proximal forearm rotation occurs from
poorly positioned humeral epicondyles
Pt with known or suspected fractures of the forearm what should you do if they are unable to place arm in position
position the area closest to the fracture in a true position ap
In a externally rotated ( lateral rotation) of the forearm what will be shown
less than 1/4 of the radial head superimposition is over ulna
In a medial rotation of the forearm
- epicondyles are not parallel
- pisiform is out
- superimposition of the 1st, 2nd, 3rd
due to the divergence of the x-ray beam what joint space is open in the AP forearm when the central ray is at mid forearm
the radioscaphoid and the radiolunate joint spaces are open
when you center at midshaft for the AP forearm what joint is closed and open
- open wrist joint
- closes off elbow joint
how much of each joint should be on the image for a lateral forearm
IR long enough to extend one inch beyond both the wrist and elbow joint
where is the most common place for avulsion fracture (hyperextending of the wrist)
ulnar styloid process
What is in profile for the lateral forearm
ulnar styloid is in profile
how should the elbow, humerus, hand, and wrist be positioned for a lateral forearm
elbow at 90 degrees, elbow, hand, wrist, in a lateral position
- humerus in the same horizontal plane
In a lateral forearm how is the distal scaphoid
the distal scaphoid is slightly distal to the pisiform and anterior to the capitate and lunate
where can you see fluid build up, effusion or fractures
pronator, supinator, or anterior fat pad
where is the most common to cut off in an lateral forearm
back of the olecranon process
In a lateral forearm what joint space is open due to the divergence of the beam
elbow joint is open
in a lateral forearm what is true lateral
the wrist and thumb are true lateral bring thumb down to the 2nd to not obscure trapezium
why should elbow be at 90 degrees for lateral forearm
to demonstrate a good anterior fat pad
in a lateral forearm what are the soft tissues of interest
anterior, posterior, supinator fat stripe at the elbow
if there is less or more than 90 degrees flexion of the elbow in a lateral forearm what happens
the anterior fat pad is distorted
anterior fat pad is with
radial head fractures
the pronator fat stripe is located
anterior surface of the distal radius
in a lateral forearm if the anterior fat pad does not look like a tear drop what happens
there is a possible indication of a radial head fractured
how is the posterior fat pad if there is an injury in a lateral forearm
you will see it in the extreme lateral edge
The posterior fat pad is pushed out with injury, what does it do to the olecranon
pushing proximal and posterior to the olecranon process
how is the posterior fat pad if its not injured in a lateral forearm
it goes into the olecranon and you wont see it
what is not in profile for a lateral forearm
the radial tuberosity is not in profile
in an external rotation (supinated) of the distal forearm wrist rotation
the pisiform will be anterior to the distal scaphoid
- ulna appears anterior to the radius
- radius posterior to the ulna
if the hand is pronated for a forearm, how is the distal scaphoid
(medial rotation)
the distal scaphoid is anterior to the pisiform and the radius is anterior to the ulna
if the elbow is still lateral
the radial tuberosity is facing anteriorly
radial tuberosity facing medially in what projection
AP forearm
poor elbow placement
can displace the fat pads
in external rotation what happens to pisiform
push pisiform out, becoming more anterior
for a lateral forearm if the proximal forearm is elevated what happens to the capitulum and trochlea
capitulum - too far anteriorly
medial trochlea- too posteriorly
which closes off the elbow joint space
what is connected to the radial head
the capitulum
Poor humeral position in a lateral forearm results in
in the capitulum and medial trochlea misalignment and also the radial head and coronoid process
when the proximal humerus ( shoulder) is elevated not in the same plane
The radial head is positioned posterior to the coronoid process
if the proximal humerus is depressed
the radial head is positioned anterior to the coronoid process
in a lateral forearm how are the epicondyles
epicondyles are perpendicular
how are the medial and lateral humeral epicondyles in a AP humerus
Medial and lateral humeral epicondyles are in profile ( parallel with the IR
In an AP humerus how is the radial head
the radial head and tuberosity are superimposed over the lateral aspect of the proximal ulna 1/4 inch
What is demonstrated in profile for the AP humerus
the greater tubercle is demonstrated in profile laterally
thumbs follows what
the greater tubercle
what is demonstrated in medial profile in an AP humerus
humeral head is demonstrated in medial profile
what is visible halfway between greater tubercle and humeral head
Vertical cortical margin of lesser tubercle
how is the radial tuberosity when the hand is supinated in AP humerus
medially
what is superimposed over the glenoid fossa in AP humerus
head superimposed over glenoid fossa
what is a result of poor humeral epicondyle positioning
rotation of humerus
how to determine the amount of rotation needed by in an AP humerus
by looking at the radial tuberosity superimposition over the ulna
how is the radial tuberosity when the hand is supinated in AP humerus
radial tuberosity is facing medially
if less than 1/4 of radial tuberosity off ulna what kind of rotation it is for the AP humerus
excessive external (laterally)
if there is more than 1/4 inch of radial tuberosity is shown on ulna , how is the rotation
the elbow and humerus has been medially rotated (internally)
what can excessive rotating due of there is a fracture of the humerus
forearm should not be externally rotated excessively , this may cause an increase risk of radial nerve damage
what should you do if there is a suspected fracture of the humerus you can’t externally rotate the humerus
move the whole body
how should you position someone with an injury that is unable to move
Joint closest to the injury should be aligned in the true AP position
what is in profile for a mediolateral humerus
the lesser tubercle is in profile medially
What is superimposed in a mediolateral humerus
humeral head and greater tubercle are superimposed
in a mediolateral humerus how is the radial head
the radial head is demonstrated anterior to the coronoid process
what else is in profile for a mediolateral humerus
the radial tuberosity is in profile
how are the epicondyles in the mediolateral humerus
the epicondyles are perpendicular to IR
which lateral of the humerus decreases distortion
mediolateral humerus
what is seen better in a mediolateral humerus
the radial tuberosity or radial head is seen better
what is seen better in a lateromedial humerus
the coronoid process is better seen
what happens when there is over rotation of the mediolateral projection of the humerus ( no longer in a PA position)
This would cause a decrease in density of the proximal humerus compared to the distal humerus
- you won’t see the proximal humerus
how are the epicondyles in a lateromedial humerus
epicondyles are perpendicular to IR
for a good lateral elbow in a lateral humerus how should the hand be
hand turned up
in a lateralomedial projection what is superimposed
the radial head and coronoid process are superimposed
what is not in profile no more in a lateromedial humerus
the radial tuberosity is no longer in profile
in a lateromedial projection how is the capitulum
the capitulum is visible distal to the medial trochlea
for a fracture of the proximal humerus what two projections can you do
- scapular y
- transthoracic lateral
use a 3 second breathing technique, proximal humerus is halfway between the sternum and the thoracic vertebrae
Transthoracic lateral position
why do we do a bluring technique for a transthoracic lateral position
it shows fracture and dislocation
- to blur ribs and lungs
