The modular external fixator is optimal for temporary use. It is rapidly applied without need for intraoperative x-rays and can be adjusted later.
Details of external fixation are described in the basic technique for application of modular external fixator.
Specific considerations for the humerus shaft are given below.
There are two typical scenarios for using an external fixator for humeral shaft fractures:
In both situations, the patient is typically placed in supine position.
Throughout this treatment option illustrations of generic fracture patterns are shown, as four different types:A) Unreduced fracture
The patient in a supine position is the preferred position for external fixation.
Beach chair and lateral position may also be used.
As in all locations of long bones safe zones for pin placement can be defined. In the typical emergency situation, the patient is supine. Therefore, the safe zone of the distal third of the humerus is not practical.
For bridging the humerus two pins are placed proximal and distal to the fracture. Proximally, the pins are placed anterolaterally. Take care not to injure the axillary nerve or the long head of the biceps.
Distally the pins can be placed laterally. Doing so, the radial nerve is at high risk. To reduce radial nerve injuries, it is recommended to use incisions large enough to ensure palpation and/or direct visualization of the radial nerve (no stab incisions). It may be better to use a single incision for the insertion of both pins.
Pearl: To minimize the size of the incision, yet still obtain adequate hold in the distal fragment it is useful to insert pins in divergent directions.
After stab incision of the skin perform a blunt dissection of the soft tissues with scissors down to the bone. Use of drill sleeves with trocar prevents damage to muscular, vascular and neurological structures.
To prevent postoperative complications, pin-insertion technique is more important than any pin-care protocol:
Various aftercare protocols to prevent pin-track infection have been advocated by experts worldwide, so no standard protocol for pin-site care is given here. Nevertheless, the following points are recommended:
If a pin loosens or there is pin-track infection, the following steps need to be taken:
Allow infected pin tracks to heal before changing to definitive internal fixation, otherwise infection will result.
Gentle use of the hand and forearm should start as soon as the patient is able to tolerate this, with some caution if pins are near the elbow. Pendulum exercises or assisted shoulder motion should be considered as soon as tolerable.
Check the wound 7-10 days after surgery. X-rays are taken to check the reduction.
The patient should be seen every 3 or 4 weeks with examination and x-rays until union is secure, and range of motion and strength have returned.
If the fixator is used for definitive fixation, it should be left until callus is visible and the fracture site is stable and non-tender. Remember the risk of delayed union or nonunion, so monitor the patient and if necessary consider alternative treatment.