Olecranon fracture

Olecranon fractures are clinically and radiographically obvious, and usually require open reduction and internal fixation.

Mechanism

Olecranon fractures occur as the result of one of four mechanisms ²:

1. direct blow (or fall directly on the elbow)
2. fall on outstretched hand with elbow flexed
3. avulsion fracture - e.g. triceps bony avulsion
4. stress fracture, e.g. throwing athletes and gymnasts

It is important to remember that the ulnar nerve is closely related to the medial aspect of the olecranon and, although not common, nerve injury may complicate these fractures ².

Radiographic features

Plain radiograph

Olecranon fractures are easy to diagnose provided a lateral x-ray of the elbow is obtained. They appear as a lucency usually reaching the trochlear groove articular surface and are, in most cases, displaced.

Reporting checklist

Radiology reports should not only include whether or not a fracture is present but also comment on:

• fracture
  • location, especially whether or not it reaches the articular surface 
  • displacement and the gap distance
  • comminution
• associated findings and relevant negatives
  • presence of fracture of the coronoid process
  • presence of fracture or dislocation of the radial head
  • presence of fracture of the distal humerus

Treatment and prognosis

Due to the unopposed traction of the triceps muscle, these fractures are usually widely displaced and require open reduction and internal fixation (ORIF) ¹. Occasionally when undisplaced non-operative treatment with immobilization at 30 degrees of flexion is possible ². Union rates with appropriate treatment are very high (~99%) and other than a slight reduction in flexion and extension at the elbow, function is preserved ^1,2.

Unlike many other intra-articular fractures, olecranon fractures result in relatively little secondary osteoarthritic changes, probably on account of most fractures occurring through a relatively non-articular part of the trochlear groove ¹.

Most of the symptoms relate to prominence of hardware given the little overlying soft tissues ¹.

Occasionally ulnar nerve injury can result in long-term sensory and motor impairment, most marked in the hand.

Differential diagnosis

There is usually little differential, especially in adults, and when the clinical presentation is that of trauma to the elbow with pain, swelling and lack of mobility. In young patients, one must consider unfused olecranon epiphysis ³. Extremely rarely it can mimic a patella cubiti.