External fixator

An external fixator is, first of all, a retaining system mounted outside the body (externally) through the skin. Here, pins are anchored in the bone and connected with an external, rigid device. Similarly, there is also an internal fixator, meaning a device that is fastened surgically to the bone and is not visible from the outside.

External fixators are frequently used to immobilize affected body parts in comminuted fractures, but also for the intentional stiffening of joints.

In the correction of the deformities described here, the ILIZAROV method is generally used.

Gavril Ilizarov (1921–1992) was a Soviet physician and surgeon who succeeded in lengthening bones with the help of an external ring fixator. His procedure, at first sight, appears as ingenious as simple. The bone is cut in a suitable place, and thus an "artificial fracture" is created. The two pieces of bone are fixed to a device, and the gap at the site of the fracture is continuously widened. This pulling apart of the two bone pieces happens at the speed at which new bone is formed—the bone grows.

To this day, the basic idea has not changed much. However, the Ilizarov techniques and external fixator ("Ili" for short) have been continuously developed further.

One of the most modern fixators is the "Taylor Spatial Frame" made by the American manufacturer Smith & Nephew.

The possibilities of this fixator go far beyond bone lengthening. It allows for computer-calculated, three-dimensional axial corrections, meaning bending and rotating of a bone.

An overview of the possibilities offered by this device can be found here.

Correction using the Ilizarov method is divided into four phases:

1. Consultation and assessment

The patient comes to the hospital for a very detailed consultation. Radiographs are made and therapy, individual chances of success and possible alternatives are discussed. The team of physicians creates a treatment plan and determines the surgical techniques to be used, as well as the exact configuration and size of the fixator.

2. Surgical mounting of the fixator

After the fixator has been "tried on" once more, it is surgically mounted. The bone/s is/are cut (osteotomy), and the fixator is connected to the bones with wires and screws. The patient remains in the hospital for approximately 10 days for postoperative care and monitoring.

3. Correction and lengthening

While still in the hospital, physiotherapy is usually already started two days after the surgical mounting of the fixator. The patient is instructed in the care and handling of the fixator, and about 3–5 days after surgical mounting, axis correction and lengthening is started. The outer connecting rods (struts) of the fixator are "turned" once or several times per day, in accordance with an individually determined schedule; the desired correction is thus achieved by lengthening/shortening the connecting rods. In case of lengthening, the bone can "grow" up to 1 mm per day using this method.

The patient can take over the daily task of "turning" the struts after discharge from the hospital. Depending on the extent of the required correction, this phase takes about 3 months. Proper progress is documented via regular X-ray examinations.

4. Strengthening

After successful correction, the newly formed bone substance is still very soft and has to harden. This phase takes approximately as long as the correction phase. The struts are no longer "turned" during this time. Once the bone has reached sufficient firmness, the fixator is surgically removed. For stabilization, the patient must wear an orthosis for approximately 1–2 months and must strengthen the bone as well as the muscles with regular physiotherapy.