Professor Ilizarov’s work demonstrated that under traction stimulus the osseous callus – on fractures appropriately produced surgically – can be modelled to produce the elongation and straightening of the long bones in the upper and lower limbs.
The application of the Ilizarov apparatus is recommended for closed comminuted fractures, fractures with or without joint involvement and open fractures with bone loss.
There are significant advantages: first of all there is the stability, which is greater when compared to unilateral fixators. Thanks to the elasticity of the wires on the apparatus, the micro movements caused by the load also favour a more rapid consolidation of the fracture site.
Another major benefit that that is obtainable from using the Ilizarov apparatus is the respect for the vascularisation of the fracture fragments. Not opening the fracture site, in fact, means there is less possibility of bacterial contamination with consequential osteomyelitis. What is more, avoiding a real surgical procedure reduces the operating risks to a minimum and does not leave any noticeable scars.
Another advantage of using this method is the allowing of the load with crutches on the first day after the procedure. This will help with the good “pump effect” on the fracture site and increase the venous and lymphatic flow, preventing oedema and osteoporosis.
The fixation of bone segments by means of crossed wires secured on circular supports, allows both a dosed longitudinal compression or distraction to be exerted, retaining the desired position of the bone fragments, and the reciprocal position of the bone segments to be modified in any direction.
The Ilizarov fixator is composed of metal rings and arches of different diameters and of perforated metal plates, for securing the wires, and which can be screwed onto the circular support. There are also turnbuckles for tensioning the wires and threaded or telescopic connecting rods.
The apparatus is created with two or more rings or arches, that have a hole every 10° around the circumference, through which three or more connecting rods can be inserted.
Tensioned by the compression-distraction or by the appropriate turnbuckle, the steel wires are secured to the rings by means of bolts that have been grooved for the passage of the wire and that are tightened using the appropriate nut.
The maximum permitted tension, in extension or compression, is 250kg whilst the individual wires can withstand a tension of 150 kg. The internal diameter of the rings for the tibia and upper limbs varies from 80 to 140 mm; that of the rings for the thigh ranges from 150 to 220 mm and the circumference of the arches varies from between 90° and 120°.
The steel wires are usually secured on a plane that is perpendicular to the diaphysis axis. For convenience the larger diameter threaded screws are used in the upper part of the femur and humerus, because they are only secured from the exterior.
At the level of the joints (hip, elbow, shoulder, wrist, etc.) the rings are replaced by arches in order to allow movement. For the same reason the insertion of the wires must allow for the sufficient movement of the skin at the joint so that it is not subjected to traction during articular excursion.