Fracture of the Coronoid

Definition

  • Fracture of the Coronoid

Incidence

  • 2 – 10 % of posterior dislocations of elbow

Classification

Coronoid fracture

Regan and Morrey (JBJS 1989)

TypeDescription
ITip of process
II< 50% of process
III> 50% of process

Original publication Regan W, Morrey B. Fractures of the coronoid process of the ulna. J Bone Joint Surg Am. 1989;71(9):1348-54.

SubtypeDescription
ANo dislocation
BDislocation

Aetiology

  • Hyperextension of the elbow. Associated with elbow dislocation up to 33% of the time.

Pathology

  • Loss of anterior bundle of MCL into coronoid
  • Trochlea shears off coronoid in hyperextension

History

  • Mechanism of Injury
  • High energy vs low energy
  • Possibility of elbow dislocation
  • Nerve symptoms in hand

Examination

  • Look
    • swelling
    • bruising
  • Feel
    • areas of tenderness
    • radial pulse
  • Move
  • Neurology
    • thorough examination of upper limb nerves

Investigations

X-rays

  • AP and lateral elbow
  • Coronoid tip may be obscured by the radial head on the lateral view
  • Oblique views improve coronoid visualisation
  • Look for dislocation and radial head fracture of a terrible triad
  • CT defines fragment size and anteromedial facet involvement

Treatment

Type I

Tip of coronoid – ignore, early ROM. Occasionally arthroscopic debridement of a prominent malunited coronoid tip is required.

Type II

Less than 50% of coronoid.
If elbow stable, early ROM
If elbow unstable, ORIF

Type III

More than 50% of the coronoid
A fracture here not only disturbs the bony anatomy but makes the anterior band of the MCL incompetent.
This can disturb the attachment of the brachialis, which provides an important dynamic stabilising effect, plus there are the consequences of the type II lesion.
Treatment is with ORIF

All types need early ROM.

In cases of instability post repair, a hinged external fixator is required.

Complications

Prognosis

  • Isolated small tip fractures do well
  • Large fragments and terrible triad injuries risk stiffness, instability and arthritis
  • Missed anteromedial facet fractures lead to varus posteromedial instability and early arthritis
  • Restoring stability allows early motion and better function

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.