Fracture, Coronoid

Ovid: 5-Minute Sports Medicine Consult, The

Fracture, Coronoid
David A. Stone
Delmas J. Bolin
  • The coronoid process:
    • An important stabilizer of the elbow to varus stress and posterior ulnar displacement.
    • Part of the sigmoid notch, the portion of the proximal ulna that articulates with the humerus.
    • Has several important soft tissue insertions:
      • The brachialis muscle inserts anteriorly, distal to the capsule; the anterior joint capsule inserts very close to the tip of the coronoid; the anterior bundle of the medial collateral ligament and the lateral collateral ligament complex insert at the base of the coronoid.
  • When the coronoid is fractured at the base, the ligament insertion sites are often preserved because failure occurs through bone, not the ligament insertions. Smaller fractures are likely to be associated with ligament injury.
  • Usual mechanism of injury is elbow dislocation as a result of a fall on an outstretched hand.
Coronoid fractures are classified based on anatomic location of the fracture; subclassification according to the associated soft tissue injuries and fractures to determine treatment (1,2):
  • Type 1: Fracture of the tip of the coronoid:
    • Tip subtype 1 fractures involve <2 mm of coronoid and may be isolated or associated with a fracture dislocation.
    • Tip subtype 2 fractures involve >2 mm and generally is associated with “terrible triad” injuries (ie, elbow dislocation, radial head fracture, and coronoid fractures).
  • Type 2: Fracture of the anteromedial facet:
    • Anteromedial subtype 1 fractures extend from just medial to the tip of the coronoid to the anterior half of the sublime tubercle (the insertion of the medial band of the medial collateral ligament).
    • Anteromedial subtype 2 fractures extend to the tip of the coronoid.
    • Anteromedial subtype 3 fractures extend to the anteromedial rim and the entire sublime tubercle but do not always extend to the tip of the coronoid.
  • Type 3: Fracture of the basal aspect of the coronoid involving >50% of the coronoid:
    • Basal subtype 1 fractures involve the basal coronoid alone.
    • Basal subtype 2 fractures are associated with fractures of the olecranon.
  • Uncommon, rarely occurring as an isolated injury
  • In elbow dislocations, 2–15% of cases have coronoid process fractures.
Risk Factors
  • Displacement of large coronoid process fracture fragments has been associated with recurrent dislocation.
  • No known significant risk factors to date
Commonly Associated Conditions
  • Elbow instability
  • Radial head fracture
  • Olecranon fracture
  • Loss of range of motion
  • Degenerative joint disease (posttraumatic arthritis)
  • Ulnar, median, radial, and anterior interosseous nerve injury
  • Brachial artery injury
  • Heterotopic ossification
  • Common mechanism is fall on outstretched hand.
  • Most patients with coronoid fractures present with elbow dislocations.
  • Direct impact is a less common cause.
Physical Exam
  • Diffuse edema within and around the elbow joint
  • Tenderness is usually multifocal. Look for radial head tenderness as well as olecranon tenderness.
  • Range of motion (ROM) is limited, and crepitus on ROM should be noted.
  • Anteroposterior instability may be present.
  • Neurovascular examination is paramount, especially if there is elbow deformity.
  • If elbow is dislocated, perform neurologic and vascular examinations before reduction. Repeat neurovascular examination after elbow dislocation is reduced, and assess for elbow instability.
  • Palpate radial head and olecranon to look for accompanying fractures.
Diagnostic Tests & Interpretation
  • Standard elbow x-ray series (anteroposterior, lateral, and 1 or both obliques) should be requested at the time of evaluation.
    • Evaluate for comminuted fractures, where reduction may not be advisable.
    • Repeat plain radiographs after elbow relocation.
  • If radial head tenderness is present, radial head view should be added to x-ray series.
  • Advanced imaging: Small coronoid fractures can be difficult to distinguish from radial head fractures, and both CT scanning and MRI should be considered if radiographs are not definitive.
Differential Diagnosis
  • Elbow subluxation
  • Posterior lateral rotatory instability
  • Acute ulnar collateral ligament sprain
  • Radial head fracture
  • Hyperextension injuries to joint capsule


Ongoing Care
  • Joint stiffness and limited ROM are common with prolonged immobilization.
  • Presence of posttraumatic arthritis correlates with patient age.
  • Pain is a common complaint in at least half of all patients after treatment.
  • 813.02 Fracture of coronoid process of ulna, closed
  • 813.12 Fracture of coronoid process of ulna, open

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