AP Elbow in Acute Flexion

AP Elbow in Acute Flexion Radiograph

Position Diagram 1

Position Diagram 2

Special Feature of this Projection

Projection in acute flexion: This technique is used when the patient cannot fully extend the elbow due to pain, contracture, or joint limitation.

Allows evaluation of joint structures while maintaining a more comfortable position for the patient.

Exposure Factors

Kilovoltage (kV)

Slightly higher due to superposition

Milliamperage (mAs)

Low, adequate for extremity

Fine Focus

Focus Type

100 cm

Source-Image Distance

Without Bucky

Configuration

Very low exposure: kV slightly higher (64) to compensate for structure superposition in acute flexion

Anatomical Structures and Features

Main objective: Rule out fractures and dislocations of the elbow when full extension is not possible

Expected Superposition Feature

The forearm and humerus should overlap due to the acute flexion position.

An optimal exposure should show:

Distal humerus visible through the superimposed forearm
Olecranon visible through superimposed structures
Joint relationship preserved despite superposition

Cassette Size

18 × 24 cm

Standard

Standard size for elbow joint evaluation

Patient Positioning

Sit patient at end of table

Place arm in acute flexion over cassette

Position cassette to include distal humerus and proximal forearm

Ensure forearm is in complete contact with cassette

Maintain position of maximum flexion tolerated by patient

Provide additional support if needed for comfort

Central Ray Point

Midway between epicondyles

Direction: Perpendicular to entry point

Location: Midpoint between medial and lateral humeral epicondyles

Consideration: Through superimposed structures in flexion

Specific Indications for this Projection

Patients with Pain

When full extension causes intense pain

Joint Contractures

Mechanical limitation of extension

Initial Evaluation

Acute trauma with movement limitation

Patient Instructions

"Remain still during the examination"

Maintain flexion position without movement during radiographic exposure

Inform technician if position causes excessive pain

Optimal Image Characteristics

Expected superposition

Forearm over distal humerus

Visible structures

Distal humerus through superposition

Olecranon visible

Identifiable process

Adequate field

Complete joint included

Common Technical Challenges

Frequent problems in AP projection with acute flexion:

Excessive superposition hiding critical structures
Inadequate exposure to penetrate multiple bone layers
Position instability due to patient discomfort
Unintentional rotation during positioning
Exclusion of important areas due to poor centering
Poor fracture identification due to superposition

Solution: Use slightly higher kV (64) for better penetration and ensure stable position with maximum patient comfort

Interpretation Considerations

Diagnostic Limitations

• Superposition hinders detailed evaluation

• May mask linear fractures

• Displacement evaluation limited

• Recommended to complement with other projections when possible

Technique Advantages

• Allows initial evaluation without forcing extension

• Useful in acute pain or contracture

• Can show obvious fractures or dislocations

• Less painful for patient