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 are 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.

The external fixator is 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 usually 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 very much. However, the techniques and the external fixator after Ilizarov - "Ili" for short - have undergone constant continuing development.

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

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

An overview of the possibilities can be found here.

The correction with the Ilizarov method is divided into four phases:

1. Consultation and assessment

The patient comes for a very detailed counseling session to the hospital. Radiographs are made and the 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 or the bones are cut through (osteotomy), and the fixator is connected to the bones with wires and screws. The patient remains approximately 10 days in the hospital for postoperational care and monitoring

3. Correction and lengthening

While still in the hospital, physiotherapy is usually started already 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. This extending or shortening of the connecting rods results in the desired correction. In case of lengthening, the bone can "grow" this way by maximally 1 mm per day.

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

4. Stabilization

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 not "turned" anymore during this time. Once the bone has reached sufficient firmness, the fixator is surgically removed. For stabilization, the patient must wear an orthesis for approximately 1-2 months and must strengthen the bone as well as the muscles with regular physiotherapy.