Metaphyseal radial fractures

Metaphyseal fractures of the radius are common in children.

The first important thing to determine is the type of fracture.

Three main fracture types:

Torus fracture - cortex bulges, only one cortex involved, stable injury.

Greenstick fracture - more severe force, compression force on one cortex and tension force on opposite cortex

Complete fracture - fracture of both cortices (see below). Length maintained or complete translation with shortening and bayonet opposition.

Torus fractures are stable, only need protection for 2-4 weeks.

Greenstick and complete fractures treatment depends on age of patient, and direction of displacement. (see What can I accept)

Direction of displacement

Displacement of the distal fragment is normally dorsal, rarely volar.

Generally volar angulation is clinically more noticeable.

What can I accept?

Generally if clinical evidence of deformity should reduce, but here is the science.

Depends on:

Age (remember sex discrepancy)
Degree of displacement
Site, closer to physis greater ability to remodel
Direction, Volar generally more apparent clinically with less degree of angulation and loose supination

In the sagittal plane: 30° of angulation in dorsal fractures with 5 years of growth remaining. Decrease the acceptable amount of angulation by 5° per year.

In the coronal plane: 20° with 5 years of growth remaining.

MUA allows application of well moulded plaster, it may still displace in well moulded cast (warn parents).

Brachioradialis muscular force continually wanting to displace fracture. Follow up radiologically weekly for first three weeks.

Treatment

Depends on age of patient, if complete fracture degree of displacement.

Undisplaced or minimally displaced fractures require simple protection while healing.

Treatment of Displaced complete fractures has some controversial aspects.

MUA and cast

Controversy exists on whether to place arm in above or below elbow cast.

If in above elbow cast, further controversy exists regarding the position of the arm.

Above elbow- forearm in pronation, supination, or neutral can make argument for any. (Deforming force Brachioradialis, relaxed in supination).
Below elbow - Must mould properly (Cast index 0.7)

Personal thought, put on well moulded below elbow taking time to mould, then complete to above elbow with forearm in neutral to slight pronation (for dorsal angulated fractures), encourage child to wear collar and cuff to hold up arm so not continually holding up arm with brachioradialis.

Immobilize for 4-6weeks.

MUA and K-wire

Single K wire avoiding physis, recent study comparing MUA and cast with MUA and K wire showed better result radiologically with MUA and K-wire, slightly flawed as removed K wires under GA and placed in new cast at 3 weeks.

Follow up

Displaced complete fractures require regular follow up and re x-ray in one week to be sure no re-displacement has occured.

Brachioradialis is the muscular force continually wanting to displace fracture. Follow up radiologically weekly for first if any concern about stbility three weeks.

References

Management of completely displaced metaphyseal fractures of the distal radius in children: A prospective, randomised controlled trial - G. J. McLauchlan; B. Cowan; I. H. Annan; J. E. Robb - JBJS B - 2002 (84) 413-417