1. The well-defined soft-tissue bulge directly posterior to the olecranon on this lateral elbow radiograph is most consistent with which pathology?
Elbow
The elbow joins the distal humerus to the radius and ulna. Routine elbow imaging is an AP, a lateral and two obliques; the Coyle methods add axial views of the radial head and coronoid process.
Overview
Bones
Distal humerus
- Capitulum (lateral)
- Trochlea (medial)
- Lateral epicondyle
- Medial epicondyle
- Olecranon fossa
- Coronoid fossa
Proximal radius
- Radial head
- Radial neck
- Radial tuberosity
Proximal ulna
- Olecranon
- Trochlear notch
- Coronoid process
- Radial notch
CRITOE, the order the pediatric ossification centers appear: Capitulum, Radial head, Internal (medial) epicondyle, Trochlea, Olecranon, External (lateral) epicondyle.
Registry must-knows
- On a lateral with the elbow at 90°, a visible posterior fat pad suggests a joint effusion and an occult fracture.
- Radial head fractures are the most common elbow fracture in adults; supracondylar fractures are the most common in children.
- External (lateral) oblique frees the radial head, neck and tuberosity from the ulna. Internal (medial) oblique shows the coronoid process in profile.
- If the elbow can't extend, take two APs: one with the humerus parallel to the IR and one with the forearm parallel.
Show 1 more
- Coyle: elbow 90°, CR 45° toward the shoulder for the radial head; elbow 80°, CR 45° away from the shoulder for the coronoid.
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Radiographs 4
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Projections 6
Tap a projection for positioning, central ray and image criteria. See every exam in the Positioning Guide ›
AP elbow
CR: Perpendicular
- Position
- Arm fully extended, hand supinated, epicondyles parallel to the IR. Shoulder at the level of the elbow.
- Central ray
- Perpendicular
- Centering
- Mid-elbow joint
- Typical technique
- 60–65 kVp · 3–5 mAs · 40" SID
Image criteria
- No rotation: epicondyles in profile.
- Radial head, neck and tuberosity slightly superimposed on the proximal ulna.
- Elbow joint open; olecranon seated in the olecranon fossa.
Lateral elbow (lateromedial)
CR: Perpendicular
- Position
- Elbow flexed 90°, humerus and forearm on the same plane, hand lateral (thumb up).
- Central ray
- Perpendicular
- Centering
- Mid-elbow joint
- Typical technique
- 60–65 kVp · 3–5 mAs · 40" SID
- Best shows
- Olecranon in profile and the anterior and posterior fat pads
Image criteria
- Elbow flexed 90°; humeral epicondyles superimposed.
- Three concentric arcs: trochlear sulcus, double ridges of the capitulum and trochlea, and the trochlear notch.
- Radial head partly superimposes the coronoid process; olecranon in profile.
AP oblique, lateral (external) rotation
CR: Perpendicular
- Position
- From the AP, rotate the hand and arm 45° laterally (hand supinated).
- Central ray
- Perpendicular
- Centering
- Mid-elbow joint
- Typical technique
- 60–65 kVp · 3–5 mAs · 40" SID
- Best shows
- Radial head, neck and tuberosity free of the ulna; capitulum and lateral epicondyle
Image criteria
- Radial head, neck and tuberosity free of superimposition.
- Capitulum and lateral epicondyle in profile.
- Elbow fully extended.
AP oblique, medial (internal) rotation
CR: Perpendicular
- Position
- From the AP, rotate the hand and arm 45° medially (hand pronated).
- Central ray
- Perpendicular
- Centering
- Mid-elbow joint
- Typical technique
- 60–65 kVp · 3–5 mAs · 40" SID
- Best shows
- Coronoid process in profile; trochlea and medial epicondyle
Image criteria
- Coronoid process in profile.
- Radial head and neck superimposed by the proximal ulna.
- Elbow fully extended.
Axiolateral for the radial head
CoyleCR: 45° toward the shoulder
- Position
- Elbow flexed 90°, hand pronated.
- Central ray
- 45° toward the shoulder
- Centering
- Radial head (mid-elbow joint)
- Typical technique
- 65–70 kVp · 4–6 mAs · 40" SID
- Best shows
- Radial head and capitulum, projected away from the coronoid
Image criteria
- Radial head and capitulum free of superimposition.
- Joint space between them open.
Axiolateral for the coronoid
CoyleCR: 45° away from the shoulder
- Position
- Elbow flexed 80°, hand pronated.
- Central ray
- 45° away from the shoulder
- Centering
- Coronoid process (mid-elbow joint)
- Typical technique
- 65–70 kVp · 4–6 mAs · 40" SID
- Best shows
- Coronoid process in profile
Image criteria
- Coronoid process elongated and in profile.
- Distal humerus and coronoid separated.
Technique values are typical starting points; follow your department's technique chart.
Labeled diagrams
Quick check
2. This AP elbow of a 6-year-old was obtained after surgery. Two crossed metal pins pass through the distal humerus. Which injury are the pins MOST likely stabilizing?
3. A patient cannot fully extend the elbow, which stays flexed about 45°. Two AP projections are needed. For the image of the proximal radius and ulna, how is the arm positioned?
4. How is the elbow positioned for a true lateral elbow like this one?
5. Which evaluation criterion shows that this lateral elbow is correctly positioned?
