While working in Kurgan in central Russia some 50 years ago Dr Gavriil Ilizarov, originator of the Ilizarov technique, devised his own external bone fixation apparatus as no other equipment was available at that time. The system consists of a series of flat, circular, steel rings joined together by long threaded bolts. When applied the apparatus encircles the limb, the rings being attached to the bone by a number of tensioned wires which pass through the tissues and bone.

This system was initially devised to treat fractures but, by a chance observation, he noted, in one patient, new bone developing in the gap between the fragments of bone where previously there had been only fibrous scar tissue. He was able to appreciate that it was the slow distraction force on the fragments of the broken bone, combined with the stability of his apparatus, which had lead to the creation of this new bone (osteoneogenesis).

The term ‘tension-stress principle’ was coined for this technique of slow, controlled distraction of the bones and, by its use, it is now possible to refashion a damaged bone so that, with time, it becomes indistinguishable from the original tissue.

The discovery of this amazing phenomenon – the dynamic conversion of fibrous tissue to bone – proved revolutionary and Ilizarov went on to develop techniques with this equipment which allowed him to treat Orthopaedic problems which, hitherto, had been insoluble.

Limb lengthening – the most obvious use for this technique is to lengthen short limbs. He showed that it is possible, by a series of operations, to increase the size of many short-limbed people so that their stature approximates that of normal individuals.


Replacement of lost bone – in some circumstances portions of normal bone are lost from a limb as a result of injury, infection or tumour. Previously this problem often necessitated either an amputation, or a long series of difficult operations in order to try and replace that bone which had been lost. By use of this technique it is possible, in many cases, to restore the bone and thus the limb to relative normality after it has been damaged by one of these conditions.

Treatment of fractures essentially the Ilizarov apparatus is an external fixator, which basically means that it is a device sited outside the skin which holds the bone. Like many of the other such devices the Ilizarov apparatus is still used in its original capacity i.e. treating fractures. Relatively simple fractures are generally managed by either a cast fixation or an intramedullary nail but it is in the treatment of complex fractures that the Ilizarov apparatus comes into its own. Its versatility allows the external frame to be configured to deal with any disarray of bone fragments and it is especially useful in managing fractures at the end of the long bones, typically problem areas in fracture treatment.

Treatment of non-unions of fractures – in this situation the broken bone, for a variety of reasons does not heal, and the ends of the bony fragments are joined by a wad of dense fibrous tissue. This weakens the limb and, in many cases, this non-union is painful. Distraction of the fibrous tissue in the gap between the fragments will, in many cases, bring about osteoneogensis in this region which will go on to heal the fracture.

Correction of deformities – a limb, again for a variety of reasons, may become deformed. The normal treatment of a bone deformity is to simply cut it and reposition the fragments in the correct position (osteotomy). This procedure, however, is often not as simple as it seems. Many of the deformities of a bone lie in several planes at once. These multi-planar deformities generally do not lend themselves to a single osteotomy and, often, a series of such operations is necessary; each with the potential for complications. In selected cases, use of the Ilizarov principle can accomplish in one procedure what would normally take several operations. Not only can deformities of the long bones be managed in this fashion deformities of the feet as well are sometimes amenable to correction in this manner.

The apparatus is infinitely variable and is constructed individually to meet the specific requirements of each person and each specific condition. When seen initially the combination of plates, wires and screws appears flimsy but when assembled and tightened it proves to be extremely strong and rigid. Adjusting the nuts or special ‘clickers’ on the equipment moves the sets of rings and brings about the necessary distraction (or compression). Various hinges, built into the apparatus, allow for the correction of deformities in different directions. While the original ‘Ilizarov apparatus’ is still in use other forms of external fixators are being developed or modified in order to take advantage of the ‘tension-stress’ principle.

The technique generally involves constructing and applying whatever apparatus is being used, before dividing the bone. It is important that the healing process is established before distraction is begun and there is usually a delay of about a week after the operation to allow this to happen before the turning of the nuts or ‘clickers’ is initiated. The distraction rate is usually set at 1mm per day and the separation of the bone fragments is continued until the desired length is achieved.

Hopefully, while the distraction is taking place bone formation is initiated in the widening gap between the bone fragments. This gap is then gradually filled by the newly formed bone. Unfortunately, once formed, it takes a long time for this bone to consolidate and to become strong enough to bear weight. It is thus necessary for the apparatus to remain on until this consolidation has taken place

It must be noted that, although use of this apparatus can bring about wondrous results, its technique is not for everyone

Where ‘osteoneogenesis’ is the aim, it may take a long time for the ‘distraction’ process, necessary to induce bone formation, to take place. The subsequent ‘consolidation phase’, during which the newly formed bone thickens and strengthens, is about twice as long. Some people cannot tolerate this constrictive device around their arm or leg for the several months which may take to complete the process.

  • Once the distraction is underway the other tissues of the limb – the muscles, tendons and nerves – start stretching and this can become quite painful.
  • The limb can become quite swollen during the distraction phase. Although allowance is made for this swelling by using generously sized rings, the swelling can reach such a size that they press into the skin, again causing some discomfort which may require readjustment or replacement of the rings.
  • The pins through the skin require regular attention. Despite careful cleaning and dressing the site of penetration through the skin can become infected, again causing some discomfort. In some instances the position of the pins may need to changed in order to cope with this.
  • The distraction generally causes linear scars in the limb as the pins move through the skin. In cases of previous trauma or infection these may be inconsequential but in instances where the skin is unblemished the presence of these scars can be upsetting.

It requires a certain amount of courage and resolve to undergo this type of treatment. Even though the limb may become painful and swollen it may be difficult, if not impossible, to ‘turn back’ once the treatment has begun. Thus, before embarking on this course the aims of treatment and its timeframe should be understood and the possible discomforts and complications considered. Further advice and comments from personal patient experience can be obtained from the Ilizarov support centre.