Forearm Imaging

Question 1

Forearm exposure factors and rationale

Answer 1

55 kVp - high image contrast, large attentuation difference
100 mA - fine focus for image detail
0.04s- gives required mAs of 4 when using 100mA, appropriate image density
No grid - minimal scatter radiation

Question 2

Imaging techniques for forearm projections

Answer 2

AP:
- arm extended at elbow and palm of hand facing upwards
- head turned away from shoulder
- shoulder must be in same plane
- centre midwar between wrists and elbow joints
- collimate elbow, wrists, shafts of radius and ulna

Lateral
- arm flexed, internally rotated 90 degrees at wrist
- all joints in the same plane (raise x-ray bed)
- centre midway btw wrist and elbow on medial aspect
- collimate elbow, wrists, shafts of radius and ulna

Trauma PA
- PA forerarm, palm facing down on IR
- ISSUE: elbow is lateral, will need additional image of PA elbow (horizontal beam PA elbow)
- centre midway btw wrist and elbow

Trauma Lateral Horizontal Beam
- horziontal beam as patient cannot move arm
- rest radiolucent pad underneath
- centre midway btw wrist and elbow
- can be done seated or supine

Question 3

Midshaft Radius and Ulna Fracture

Answer 3

great displacement in radius and ulna

Question 4

What projections for Midshaft Radius and Ulna Fracture? Explain rationale for each

Answer 4

AP Forearm - provides full length view of radius and ulna, fracture pattern visible
Lateral Forearm - assess if any anterior or posterior displacement, look at joints

Question 5

Radiographic appearance of Midshaft Radius and Ulna Fracture

Answer 5

visible fracture lines, possible displacement

Question 6

Greenstick/ Torus Fracture

Answer 6

only occuring in children, fracture on one side of the bone, causing a bend in the other

Question 7

What projections for Greenstick/Torus Fracture in forearm? Explain rationale for each

Answer 7

AP forearm - full view of radius and ulna, to see where fracture lines are
Lateral Forearm - to assess if there is any anterior or posterior displacement

Question 8

Radiographic appearance of greenstick/torus fracture in forearm

Answer 8

clear fracture on one cortex only, possible angulation of bone shaft, compression of bone

Question 9

Monteggia Fracture/Dislocation

Answer 9

fracture to shaft of ulna and dislocation of proximal end of radius

Question 10

What projections for Monteggia Fracture/Dislocation? Explain rationale for each

Answer 10

**AP Forearm **- visualise full length of radius and ulna to see where the fracture line is
**Lateral Forearm **- to assess if there is any anterior/posterior displacement, look at if any dislocation of joints

Question 11

Radiographic appearance of Monteggia Fracture/Dislocation

Answer 11

fracture in the shaft of the radius or ulna, dislocation of the radial head

Question 12

Galeazzi Fracture/Dislocation

Answer 12

fracture of the distal 1/3 of the radius with dislocation of the distal radioulnar joint

Question 13

What projections for Galeazzi Fracture/Dislocation? Explain rationale for each

Answer 13

AP Forearm - to visualise full view of radius and ulna and alignment at the wrist
Lateral Forearm - shows posterior/anterior displacement of distal radius and ulna

Question 14

Radiographic appearance of Galeazzi fracture/dislocation

Answer 14

• fracture to shaft of the distal radius
• dislocation/subluxation of radioulnar joint

Question 15

Proximal Ulna Fracture

Answer 15

fracture to the proximal ulna

Question 16

What projections for Proximal Ulna Fracture? Explain rationale for each

Answer 16

AP Forearm - to see the full length of the ulna and see where the fracture line is
Lateral Forearm - to see if there is any anterior/posterior displacment of joints

Question 17

Radiographic appearance of proximal ulna fracture

Answer 17

• fracture in the proximal ulna
• possible displacement