Step 1 topics → Musculoskeletal, Skin, and Connective Tissue → Clavicle Fracture

Clavicle Fracture

USMLE Step 1 trap: Misidentifies the most common clavicle fracture location as medial rather than middle third. Clavicle fractures most commonly occur at the middle third (80%), with the lateral third being the second most common site.

Clavicle fractures are straightforward anatomically but get tested in ways that trip up students who memorize surface-level facts. The clavicle is the most commonly fractured bone in the body, and USMLE Step 1 will give you a mechanism (fall on outstretched hand, direct blow to shoulder, birth trauma) plus physical findings and ask you to identify the fracture location, understand the neurovascular risks, or choose appropriate management. The key is knowing not just that fractures happen, but where they happen and what structures are nearby.

The exam tests this at two levels. First, pure recall: which third is most commonly fractured, and what are the physical findings? Second, applied anatomy: what neurovascular structures are at risk depending on fracture location? A middle-third fracture puts the subclavian vessels and brachial plexus at risk — you need to know this going into any vignette that mentions arm weakness, absent radial pulse, or vascular injury after shoulder trauma. Lateral-third fractures have a different complication profile: coracoclavicular ligament disruption, which affects shoulder stability.

What makes this tricky is a common misconception about fracture location. Students sometimes guess medial third because the sternoclavicular joint 'seems important' or because it's where they'd expect force transmission — but 80% of clavicle fractures occur at the middle third. The medial third is actually the least commonly fractured site. USMLE Step 1 tests this directly by asking for the most common location, or indirectly by describing neurovascular compromise that implies a middle-third mechanism.

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Common misconceptions

Common mistake
Wrong: Clavicle fractures most commonly occur at the medial third near the sternoclavicular joint.
Right: Clavicle fractures most commonly occur at the middle third (80%), with the lateral third being the second most common site.
The medial third feels like a logical fracture site because it's near the sternoclavicular joint and force often transmits medially — but the clavicle is actually thinnest and least supported at its middle third, making that the biomechanical weak point. Middle-third fractures account for roughly 80% of clavicle fractures; lateral-third fractures are second (~15%); medial-third are the rarest (~5%). On USMLE Step 1, if a question asks about the most common location or describes neurovascular complications after clavicle trauma, default to middle third unless the vignette specifies otherwise.
Common mistake
Gap: Missing awareness that clavicle fractures carry risk of subclavian vessel or brachial plexus injury and that lateral fractures may disrupt coracoclavicular ligaments
Clavicle fractures, particularly of the middle third, can injure the subclavian vessels or brachial plexus, and lateral third fractures are associated with coracoclavicular ligament disruption.
The subclavian artery and vein run directly posterior to the middle third of the clavicle, and the brachial plexus roots are just deep to that — so a displaced middle-third fracture can lacerate or compress these structures. Clinically this shows up as diminished radial pulse, arm weakness, or paresthesias after shoulder trauma, and Step 1 will expect you to connect those findings to vascular or nerve injury rather than just the bone itself. For lateral-third fractures, the neurovascular risk is lower but ligamentous injury (specifically disruption of the coracoclavicular ligaments) becomes the concern, potentially causing superior displacement of the clavicle and shoulder instability.
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What the exam tests

  1. Given a mechanism of injury (fall on outstretched hand, direct shoulder impact, birth trauma during delivery), identify the expected presentation of a clavicle fracture including visible deformity, tenderness, and the classic downward-displaced shoulder posture.
  2. Identify the middle third as the most common location for clavicle fractures (~80% of cases), and distinguish middle-third from lateral-third fractures based on associated injury patterns.
  3. Recognize that middle-third clavicle fractures carry risk of subclavian vessel or brachial plexus injury, and that a thorough neurovascular exam (pulses, sensation, motor function) is essential.
  4. Know that lateral-third fractures can disrupt the coracoclavicular ligaments (conoid and trapezoid), affecting acromioclavicular joint stability — and distinguish this from AC joint separation.
  5. Choose between non-operative management (arm sling for most fractures) and operative fixation (displaced fractures, neurovascular compromise, open fractures, failed conservative treatment).

Can you avoid these mistakes?

A 22-year-old cyclist falls onto his right shoulder and presents with point tenderness at the midclavicular region, a visible bump over the clavicle, and the right shoulder drooping inferiorly. Which third of the clavicle is most likely fractured, and what neurovascular structures should you assess?
A patient with a clavicle fracture has a diminished radial pulse and weakness of intrinsic hand muscles on the ipsilateral side. What structures have been injured, and where along the clavicle is the fracture most likely located?
A lateral-third clavicle fracture is identified on X-ray. Beyond the fracture itself, what additional injury should you be concerned about, and why does it matter for shoulder function?
A newborn is delivered via difficult vaginal delivery and is noted to have decreased movement of the right arm. Exam shows crepitus over the right clavicle. What is the diagnosis, what is the most common fracture location in this setting, and how is it managed?

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