What does a normal clavicle x-ray (x-ray) image show?

Normal Clavicle X-ray Appearance

A normal clavicle x-ray shows an S-shaped long bone with smooth cortical margins, uniform density, and well-defined articulations at both the sternoclavicular and acromioclavicular joints, without evidence of fracture, dislocation, or other pathology.

Standard Radiographic Views

The standard radiographic evaluation of the clavicle includes:

• Anteroposterior (AP) view: The primary view showing the full length of the clavicle from the sternoclavicular to the acromioclavicular joint
• 20° cephalic tilt view: Provides better visualization of the middle third of the clavicle by reducing overlap with surrounding structures 1
• Upright positioning: Preferred over supine positioning as it better demonstrates the true alignment and any potential displacement 1

For more comprehensive evaluation, additional views may include:

• 45° cephalic tilt
• 45° caudal tilt

These additional views significantly improve visualization of anterior-posterior displacement and can affect treatment decisions in cases of fracture 2.

Normal Anatomical Features

A normal clavicle x-ray will demonstrate:

1. Overall morphology:

   • S-shaped contour with anterior convexity in the medial two-thirds and posterior convexity in the lateral third
   • Length typically between 140-150mm in adults (varies by sex and individual)
   • Uniform cortical thickness throughout the shaft

2. Medial end (sternal end):

   • Clear articulation with the sternum at the sternoclavicular joint
   • Slightly enlarged compared to the shaft
   • May appear more radiolucent due to its predominantly cancellous structure

3. Middle portion (shaft):

   • Tubular structure with uniform cortical thickness
   • No evidence of cortical disruption or step-offs
   • Smooth periosteal margins

4. Lateral end (acromial end):

   • Flattened appearance where it articulates with the acromion
   • Clear articulation at the acromioclavicular joint
   • Normal acromioclavicular joint space (typically 3-8mm)

5. Surrounding structures:

   • Normal relationship with the coracoid process (the distance between the coracoid process and the upper part of the clavicle is the most reliable measurement of AC joint integrity) 3
   • No abnormal calcifications in surrounding soft tissues

Age-Related Considerations

• In pediatric patients, the clavicle is the first bone to ossify in the body
• In adolescents, significant growth continues through adolescence and early adulthood 4
• The medial clavicular physis does not fuse until 23-25 years of age 4
• In neonates with suspected birth-related clavicle fractures, ultrasound may be preferred for follow-up imaging to avoid radiation exposure 5

Common Pitfalls in Interpretation

1. Projection errors: Inadequate positioning can create false impressions of fractures or dislocations

   • Ensure standardized positioning with proper patient alignment
   • Upright radiographs are superior to supine for demonstrating true displacement 1

2. Anatomical variants: Normal anatomical variations can be mistaken for pathology

   • Congenital pseudarthrosis
   • Developmental anomalies
   • Prominent deltoid tubercle

3. Overlapping structures: Surrounding structures can obscure clavicular details

   • First rib overlap
   • Pulmonary apex
   • Shoulder girdle structures

4. Inadequate views: Standard AP views alone may miss certain fractures or displacements

   • Additional views (especially with cephalic or caudal tilt) significantly improve visualization of displacement 2

By understanding these normal radiographic features and potential pitfalls, clinicians can more accurately interpret clavicle x-rays and distinguish between normal anatomy and pathological findings.