Paediatric Olecranon fracture

Olecranon fractures are uncommon in children, accounting for between 4% and 7% of all childhood elbow fractures.

Minimally displaced or undisplaced fractures account for 80% of all olecranon fractures, these are managed with immobilization alone and rarely require hospital admission. Of those fractures admitted to hospital oblique metaphyseal fractures are most commonly seen and are satisfactorily treated with tension-band techniques.

Clinical

The injury is commonly caused by a force transmitted up the forearm after a fall on the outstretched hand. The force may be valgus or varus, the resulting fracture is commonly an oblique fracture through the metaphysis, the direction of which may vary according to the degree of elbow flexion. Other causes include direct trauma.

Fractures through the apophysis and the growth plate are much less common and probably arise from similar mechanisms. The presence of an associated bony injury at the elbow is a common finding, with the reported incidence varying from 14% to 77%.

Radiology

The secondary centre of ossification for the olecranon appears at about 9 years old and fuses by about 14 years old. The ossification centre may be bipartite and eccentric, and as the proximal ulna grows, the growth-plate orientation alters from transverse to oblique. Closure of the physis begins at the articular surface and progresses toward the extensor surface of the bone. Just before fusion of the growth plate, the metaphyseal bone develops a sclerotic margin and may be widely separated from the apophysis, resembling a fracture. These vagaries can make it difficult to recognize a fracture of the olecranon in a child, and comparative views of the opposite side are often valuable.

Classification

Several classification systems have been proposed for fractures of the olecranon in children. Each of these address certain facets of this fracture.

Chambers and Wilkin's classification is based on the mode of injury
Graves and Canale used displacement of the fracture
Papavasiliou, classified the fracture according to joint involvement and displacement.
Matthews combined displacement with associated injuries
Evans used, the anatomic site, fracture configuration, degree of displacement, and presence of associated injuries

Evans classification below

A. Anatomic site	B. Fracture configuration: (angulation of the fracture line to the long axis of the ulna)	C. Intraarticular displacement	D. Associated injuries (ipsilateral elbow and upper limb)
1. Epiphyseal (apophyseal) a. Extraarticular, olecranon-tip fracture b. Intraarticular 2. Physeal (Harris-Salter equivalents) 3. Metaphyseal a. Juxtaphyseal b. True metaphyseal 4. Combined olecranon-coronoid process injury	1. Transverse (0-30º 2. Oblique (30-60º) 3. Longitudinal (>60º)	1. 0-1 mm displacement 2. 2-4 mm displacement 3. >4 mm displacement	1. Radial head/neck fracture 2. Radial head dislocation/subluxation (Monteggia variant) 3. Lateral humeral condylar physeal injury 4. Medial humeral condylar physeal injury 5. Supracondylar humeral fracture 6. Distal radius/ulna fracture

The fracture most commonly seen is metaphyseal with either a transverse or oblique configuration.

Treatment

Appropriate treatment of olecranon fractures depends on:

Anatomic site and pattern of the fracture
Fracture displacement (Intraarticular displacement)
Fracture stability
Extensor mechanism integrity
The presence of associated injuries.

Approximately 80% of olecranon fractures are minimally displaced and can be managed by immobilization and rarely require hospital admission.

Various authors recommended 3, 4, and 5 mm of intraarticular displacement as the threshold for open reduction and internal fixation.

This suggests that fractures with 4 mm displacement should be reduced and fixed.

This leaves a "grey zone" of displacement between 2 and 4 mm in which the management is not so clear cut, and the decision may be influenced by other factors such as, integrity of the elbow-extensor mechanism and the presence of other injuries. It should also be emphasized that a "step" in the articular surface with only slight "separation" is potentially far more deleterious to the joint than a wider simple separation without a step, which may heal with a smooth fibro cartilaginous surface.

The presence of associated injuries indicates, along with mode of injury, the severity of injury. Ipsilateral associated injuries occur in 14% to 77% of cases. The commonly seen associated injuries are radial neck fracture, lateral or medial condyle fracture, and radial head dislocation or subluxation . The elbow is often immobilized for a longer period when there are associated injuries, which in itself predisposes to stiffness.

Fixation methods

Screw fixation
Tension band constructs (Tension band suture has been shown to be a safe and effective alternative to Tension band wiring)

Outcome

Morrey et al. demonstrated that the activities of daily life require 100º of elbow flexion and extension (range, 30º flexion to 130º flexion) and 50º each of pronation and supination. Therefore it is only when a significant range of movement is lost, as in the patients with AVN and radioulnar synostosis, that the functional limitation becomes noticeable.
A change in carrying angle at the elbow is not necessarily correlated with poor functional outcome.

It is difficult to predict in the valgus injury (metaphyseal olecranon and radial neck fracture) when an associated radial neck fracture will cause an increase in carrying angle, ideally angular deformity at the radial neck should be reduced.
The best predictor of outcome regardless of treatment, is the presence of an associated injury.

Olecranon Fractures in Children: Part 1: A Clinical Review: Part 2: A New Classification and Management Algorithm. Evans, MC; Graham, HK: J Pediatric Orthop, Volume 19(5).September/October 1999.559