Fracture of the Coronoid

Definition

  • Fracture of the Coronoid

Incidence

  • 2 – 10 % of posterior dislocations of elbow

Classification

  • Classification – Regan & Morrey (JBJS 1989)
    • I = tip of process
    • II = < 50 % of process
    • III = > 50 % of process
    • (± A = no dislocation, B = dislocation)

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

Xrays

Treatment

Type I

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

Type II

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

Type III

More than 50% of the coracoid
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 stabilizing 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

  • Nonunion
  • Malunion
  • Nerve problems
  • Stiffness

Prognosis