Ilizarov Technique and Its Application

What Is Ilizarov Technique?

The Ilizarov technique is a modern approach to bone reconstruction. It emerged in the mid-twentieth century and includes various techniques for bone reconstruction utilizing an external ring fixator, which G.A. Ilizarov invented in 1951 in the Soviet Union. The fundamental biomechanical principle underlying this technique is the law of tension stress. This principle proposes that sustained and gradual traction stimulation can facilitate the regeneration and active proliferation of biological tissues, such as embryonic tissue development. Due to bone tissue's excellent regenerative capacity and plasticity, it can extend to adjacent nerves, blood vessels, muscles, and skin when subjected to suitable tensile stress. This phenomenon is recognized in orthopedic practice as distraction osteogenesis.

What Is the Principle Behind the Ilizarov Technique?

The idea of the Ilizarov technique is based on the concept of distraction osteogenesis. In distraction, new bone formation occurs across the complete cross-sections of each distracted bone surface, characterized by a central radiolucent fibrous interzone comprising type I collagen. Bone trabeculae develop directly from this central collagen region, extending towards both surfaces of the bone.

This newly formed bone is aligned parallel to the distraction force's direction and encircled by blood vessels. Muscles can accommodate lengthening of up to 10 percent without significant issues. However, lengthening beyond 30 percent leads to notable histopathological alterations. Histological examinations revealed that nerves, arteries, and veins experienced temporary degenerative changes, which resolved within two months post-lengthening.

The Ilizarov technique principles are based on the biomechanics.

These biomechanics are based on the following factors:

1. Relationship Between the Transosseous Elements and the Surrounding Tissues: Circular fixators consist of multiple elements, with the primary components being rings and connecting rods. Complete rings provide maximum stability, while partial rings and arches are especially advantageous when operating near joints, facilitating access to wounds following trauma. The ring frame supports and stabilizes the underlying bone by utilizing transfixion wires and half pins. The stability of the frame is enhanced by increasing the diameter and tension of the cables, employing a more significant number of wires per ring, positioning wires on opposite sides of the ring, and inserting wires at various planes. Achieving crossing angles of the wires up to 90 degrees maximizes stability. In comparison, angles less than 60 degrees may permit the bone to shift along the wires, necessitating opposing olive wires or the incorporation of a half pin. Half-pins intended for placement in the diaphysis and metaphysis must be aligned with the cortical and spongy threads. It is essential to ensure that the half-pin passes through both cortical plates.

2. Control of Bone Fragment Position:

For optimal management of bone fragment positioning, the external fixation apparatus must facilitate controlled movement of the fragments across three-dimensional space, encompassing six standard degrees of freedom, both in a single motion and progressively over time. Two methods mainly do this. One method involves moving both external supports with the transosseous modules, and another involves adjusting the transosseous components about the external supports while keeping both the external supports and the device modules stationary.

3. Control of Bone Fragment Rigidity:

The key factors affecting the rigidity of bone fragment fixation, which are essential for all varieties of transosseous devices, are discussed below:

• The rigidity of the material used in constructing the components of the external fixation device directly correlates with the strength of the fixation of the bone fragment. As a result, components of stainless steel, titanium alloys, and chromium-cobalt-molybdenum alloys are very effective.

• Increasing the diameter of the transosseous components will result in greater rigidity of the bone.

• An increase in the quantity of transosseous elements placed within each bone fragment correlates with enhanced rigidity of the transosseous synthesis. However, a higher number of interventions results in a corresponding rise in trauma levels and an elevated risk of joint stiffness caused by the pins.

What Are the Clinical Applications of the Ilizarov Technique?

The Ilizarov technique can be applied in various clinical situations.

These are;

1. Infected bone nonunion presents two significant orthopedic challenges: infected nonunion accompanied by osteonecrosis. The continuous movement in the traditional treatment method hinders the healing of fracture segments and the management of the infected scar tissue. Implementing rigid fixation and bypass surgery can help reduce soft tissue damage and promote healing. The Ilizarov external fixation method provides a highly adaptable approach to these complex issues, allowing for the treatment of bone defects while simultaneously managing the infection, ultimately leading to the best possible therapeutic outcome.

2. Infected bone nonunion frequently results in significant bone loss following debridement, which can cause limb shortening and deformity. Repairing segmental bone defects is commonly associated with various complications, such as infection, rejection, bone nonunion, and bone graft fractures. Consequently, applying the Ilizarov Technique with vascularized autogenous bone grafts is a highly effective approach for addressing extensive segmental bone defects.

3. One of the most common uses of this technique in today’s world is treating dwarfism. The Ilizarov technique for height increase is gaining popularity, as this method can increase a person's height by up to six inches within two to three months.

What Are the Complications Associated With the Ilizarov Technique?

The most common complications associated with this technique are neuromuscular damage. Apart from this, complications like hematoma (a collection of blood outside the blood vessels), bleeding from the site, deep vein thrombosis (presence of clots in the blood vessels), and infection in the pin sites can be observed.

Conclusion:

The Ilizarov technique is a modern method of bone reconstruction. This method is based on the law of tension stress, which causes distraction osteogenesis. The new bone formed in this process helps treat bony infection, non-union, and dwarfism. However, this may lead to complications like localized tissue infection and deep vein thrombosis.