Elbow X-ray Interpretation: A 3 Step Approach

Elbow X-ray interpreted by following this 3 steps approach:
- Step 1: assess Bones
- Step 2: assess Joints
- Step 3: assess Soft tissue

Step 1: assess Bones

Trace the edges of each bone looking for cracks
If you see the fracture then start with the fracture then look elsewhere
Look at the general appearance of the bone looking for decrease or increase in density (osteopenia vs osteosclerosis) or abnormal trabeculation (Paget’s disease)

Assess the radiohumeral joint, ulnohumeral joint and radioulnar joint
Look for the shape of the joint, congruity of the bone ends and look for narrowing or asymmetry
Elbow lines: radiocapitellar line, anterior humeral line

Radiocapitellar line is used to look for radial head dislocation
Radiocapitellar line is drawn from the neck of the radius to the capitellum and should intersect the capitellum in all views

Anterior humeral line is used to check for subtle supracondylar fracture on lateral elbow x-rays
Anterior humeral line is drawn down the anterior surface of the humerus and should intersect the middle third of the capitellum
In normal children younger than 4 years, anterior humeral line might intersect the anterior third of the capitellum and this is normal in this age group

Look for changes in density, abnormal bulges, swelling, foreign bodies
Higher density soft tissues are muscles while lower density soft tissues are fat
On the lateral elbow radiograph, Inspect for elevation of the anterior and posterior fat pads; anterior fat pad can be seen in normal x-rays but posterior is not
Elevation of these fat pads known as the sail sign, this indicates a joint effusion and it occur in elbow trauma, fractures and inflammation

Pediatric elbow X-rays is harder to be interpreted because of the ossification centers order of appearance
The order of appearance for the elbow ossification centers: “CRITOE”
- Capitellum: 1 year of age
- Radial head: 3 years
- Internal epicondyle (medial): 5 years
- Trochlea: 7 years
- Olecranon: 9 years
- External epicondyle (lateral) : 11 years

Primary radiographic series for elbow injuries is the AP and lateral views; those are the most common ones to be ordered
Those are indicated in elbow injuries and various elbow conditions
But there is other views that can be taken to look for specific elbow injuries or taken because of lack of patient mobility
Those include:
- Modified trauma views
  - Horixontal beam lateral:
  - Acute flexion AP:
  - Inferosuperior view
- Additional views
  - Coyle’s view
  - External oblique
  - Inferior oblique view:
  - Supraconylar AP