Andrew Howard, Theddy Slongo, Peter Schmittenbecher
The versatility of a modular external fixator is an advantage in the management of children’s fractures and can accommodate age specific variations in fracture biology and anatomy.
An external fixator may be used for definitive management of forearm fractures in children due to the short healing time.
Practical considerations are illustrated in detail in the Basic technique for application of modular external fixator in children.
Specific considerations for the forearm shaft are given below.
Alterative configurations are available and include monolateral or ring systems.
Disadvantages of these systems in children include:
External fixation is suitable for all ages, but the pin diameter must be appropriate to the size of the bone.
Pins with a thread diameter of 2.5-4.0 mm are suitable for forearm fractures and should be about 1/3 of the bone diameter.
The forearm anatomy is complex due to the presence of three major neurovascular bundles. Pin placement should avoid these structures.
Read more about Safe zones for pin placement in the ulna.
This procedure is normally performed with the patient in a supine position.
Insert the proximal ulnar pins through the subcutaneous cortex of the posterior border of the ulna between the extensor and flexor muscle masses.
Make an 8-10 mm skin incision over the site of pin insertion.
Use an artery clip for blunt dissection down to the bone, protecting important anatomical structures.
The posterior border of the ulna is subcutaneous and offers the best access.
Insert the pin in the near cortex and through the center of the bone into the far cortex.
Take care not to advance the tip of the pin beyond the far cortex to avoid damage to neurovascular structures.
Pins should not be placed closer than 1 cm to the physis.
Safe access to the subcutaneous dorsomedial cortex is improved with the elbow flexed and the forearm in mid-supination.
Insert the distal ulnar pins from dorsomedially between the extensor carpi ulnaris and flexor carpi ulnaris.
As the distal ulna in children has a small diameter, oblique pin placement improves bony contact.
Pins should not be placed within 1 cm of the physis.
Once the fracture is reduced and stabilized, the position may be checked with an image intensifier.
The rotation of the forearm is also assessed clinically. Pronation and supination may be limited by the injury and fixator configuration.
If there is important radiological malalignment or functional restriction, the external fixator may be adjusted.
There is no universally agreed protocol for pin site care.
The following points are however recommended:
Pin site infection Initial management is with oral anti-staphylococcal antibiotics.
In case of pin loosening or unresponsive pin site infection, the following steps should be taken:
Internal fixation following an infected external fixator pin has a high risk of infection and should be avoided unless no reasonable alternative is available.
See also the additional material on postoperative infection.
See the additional material on compartment syndrome.
Elevation is useful in the initial stages. A sling is helpful if fixator configuration allows its application.
The patient should be encouraged to move the wrist and elbow, within the limits of comfort.
The patient should be seen 7-10 days after surgery for a wound check.
X-rays are taken to check stability and alignment.
See also the additional material on healing times.