Reconstructive Limb Surgery — Ilizarov Method

All modern limb-lengthening operations around the world are based on Ilizarov's discovery, “The general biological property of tissues to respond to stretching with growth and regeneration — the Ilizarov effect” (1973). It means that if tissues are stretched gradually at a certain rate, new, identical tissue forms (regenerates).

The lengthening technique is simple. After the osteotomy and application of the frame, the bone fragments are gradually pulled apart by increasing the distance between the proximal and distal supports on the threaded rods that connect them.

Numerous experimental and clinical studies have established the optimal distraction rate of 1 mm per day. The more even the distraction, the shorter the period of regenerate bone formation and the shorter the treatment.

In practice, patients carry out the distraction themselves by increasing the distance between the supports on the rods. The nuts are turned by 90° every 6 hours. The pitch of the M6 thread on the rods of the Ilizarov frame is 1 mm, so one full 360° turn of the nut per day equals 1 mm of lengthening. Distraction begins 5–7 days after the osteotomy.

The total time in the frame consists of a distraction period and a fixation period. During distraction, the distance between the fragments increases and the segment lengthens. During fixation, the regenerate bone matures and finally joins the bone fragments firmly together.

Treatment takes a long time. Its approximate duration can be calculated with the formula:

A 5 cm lengthening of the tibia will therefore take 7.5 months on average. It should be noted that these time frames are very approximate and that the duration of treatment cannot be predicted in every individual case.

It is important to remember that the body's resources have their limits. Lengthening a limb by large amounts is dangerous. We are used to expressing the amount of lengthening in absolute units of length, in centimetres, but it is more accurate to speak of the relative amount — a percentage of the original length. The optimal amount of lengthening is no more than 10–15% of the original length of the segment. For example, if the tibia is 35 cm long, the acceptable amount of lengthening is 53 mm (15% of 35 cm).

Two main factors limit lengthening:

• the regenerate does not form (it dissolves and takes on an hourglass shape);
• the tendons resist the lengthening.

The main recommendation is therefore not to be greedy and not to attempt to lengthen a limb by a large amount. That leads to serious complications (long treatment periods, joint contractures and subluxations). It is better to limit the lengthening to 10–15% of the original length.

If a significant lengthening is needed, it is best done in several stages. For example, if one leg is 10 cm shorter, it can be lengthened twice by 5 cm, with a recovery period between the two operations.

In reconstructive surgery of the lower limbs, lengthening is used in two situations:

• to correct a leg length discrepancy (lengthening the shorter limb);
• to increase height in certain conditions (for example achondroplasia) or at the patient's request. In such cases both legs are usually lengthened at the same time.

The regenerate bone formed during distraction and subsequent fixation is truly the patient's own bone. A few years after surgery the site of the osteotomy and lengthening is practically impossible to find on X-rays. The bone in this area is as strong as it was before the operation.

Lengthening procedures, including the operation and the postoperative period, require a responsible and serious attitude on the part of the patient. Regular communication with the treating doctor is essential.

The details of the forthcoming treatment, the prospects and the prognosis for achieving the desired result are discussed during the consultation with Professor Aleksandr Artemev.

When the leg axis is shifted into varus or valgus, one compartment of the knee carries almost the entire load and the cartilage on that side wears rapidly. A corrective osteotomy of the thigh or lower leg restores the mechanical axis and redistributes the load: the damaged compartment is unloaded by about 70%, pain decreases and the remaining cartilage gets a chance to recover.

Osteotomy is considered the gold standard for grade 1 to 3 knee osteoarthritis in patients aged 15 to 70 — performed in time, it postpones or entirely removes the need for a knee replacement in many patients. The basic investigation is a standing full-length X-ray of both legs, which shows the size of the deformity, the affected compartment and the optimal level for the osteotomy.

Compared with plate fixation, the Ilizarov frame allows both legs to be operated on at once, the axis to be adjusted precisely and gradually — including deformities in several planes — and the patient to walk with weight-bearing from the first days. Where indicated, the osteotomy is combined with knee arthroscopy in the same session, and a slight lengthening of the bone restores tension in the collateral ligaments and further stabilises the joint.

True bow legs (varus deformity) are recognised by the knees not touching when the feet are together, leaving a gap along the inner contour of the legs from the groin to the feet. They must be distinguished from so-called false curvature, where the bones are straight and the impression of bowed legs is created by the distribution of the soft tissues of the lower leg. In Prof. Artemev's classification of 2001 it is precisely this distinction that determines the method of correction. Bow legs are by far the most common reason for aesthetic correction — 15 to 20 times more common than knock knees.

A deviation of the leg's mechanical axis is not merely an aesthetic problem: it overloads the inner compartment of the knee, so the cartilage wears faster and knee osteoarthritis appears earlier. Correction is therefore recommended as soon as possible after growth is complete. True curvature cannot be corrected with exercise, massage or braces — a deformed bone cannot be stretched straight. In children the deformity is usually observed until about the age of 8; if a disease is the cause (for example Blount's disease) surgery is done earlier, otherwise one waits for the growth plates to close, between the ages of 14 and 18.

The correction is performed through an osteotomy made via a puncture of about 5 mm, most often on the lower leg, which is technically simpler and safer than the thigh. In the Ilizarov frame the bone is then gradually brought into the correct axis, and where needed the rotation, the sideways shift of the lower fragment (medialisation, added at the patient's request in about 60% of cases), the position of the fibular head and the length of the leg are corrected at the same time — most often a lengthening of 2 to 4 cm for better proportions. The patient takes part in deciding the final shape of the legs, and the frame, weighing about 900 g, can be hidden under loose clothing.

The frame is worn for about three months on average; each centimetre of lengthening adds roughly a month. In suitable cases so-called express methods are possible, in which the frame is combined with an intramedullary nail, so it is worn for a much shorter time and active rehabilitation begins after two to three weeks. Which method is most suitable is decided at the consultation on the basis of the examination and a standing full-length X-ray of both legs.

True knock knees (valgus deformity) are recognised by the gap between the feet when the knees are together in a relaxed stance. An axis deviation of up to 10–15° is considered a cosmetic problem, more than 15° an orthopedic one. This leg shape is an ethnic trait, more common among Europeans; surgical correction of knock knees is sought 10 to 15 times less often than for bow legs, and men present two to three times more often than women.

In trousers, legs with a slight deformity look straight, while with a pronounced deformity clothes fit badly — a frequent reason for seeing a doctor. Valgus deformity is often accompanied by underdevelopment of the femoral condyles and flat feet, and it can progress with age, so correction is recommended as early as possible. Static deformities — valgus knees, bunions (hallux valgus), flat feet — are linked to the way connective tissue develops: when one is found, examination for the others is advisable, and children suspected of a deformity should see an orthopedic surgeon at least once a year.

The principle of surgical treatment is the same as for bow legs, only the shift is directed the opposite way. Three options are available: classic correction in the Ilizarov frame, the express method, and the improved express method with intramedullary nail fixation, in which active rehabilitation begins around day 19 after surgery. The legs can be lengthened at the same time for a more harmonious appearance. It is the curved segment itself that is corrected; correction of the lower leg is technically simpler and causes fewer complications than operations on the thigh.

In open and severely comminuted fractures, fractures with soft-tissue damage, gunshot and infected fractures, inserting plates or nails carries a high risk of infection and nonunion. The Ilizarov frame fixes the bone with thin wires away from the fracture site, without foreign material in the wound, so the soft tissues and wounds can be treated while the bone heals.

The fragments can be repositioned precisely and gradually in the frame even after surgery, without reopening, which is especially important in complex fractures near joints — ankle and pilon fractures, fractures of the elbow and wrist. The stability of the frame allows early mobilisation of the neighbouring joints and weight-bearing, preserving function and preventing contractures.

The method is also the answer for fractures that have healed in the wrong position (malunion): the bone is cut again at the site of the deformity and gradually straightened in the frame, with any shortening made up. The frame is worn until the bone has fully united — usually several months for complex fractures of the lower leg — and in the final phase of treatment the patient as a rule walks without crutches.

Osteomyelitis is a purulent infection of bone that most often develops after open fractures, after surgery with plates, nails or joint prostheses, and around the wires of external fixators. Bacteria are a necessary but not a sufficient condition: what matters most is the poor state of the bone and surrounding soft tissues — impaired circulation and necrosis after severe injuries — and the presence of foreign material on which the infection persists. Antibiotics are an indispensable part of treatment, but on their own they cannot cure chronic bone infection.

The basis of treatment is surgical, and in a defined order: removal of foreign material, radical resection of non-viable, infected bone and soft tissue, then achieving union and load-bearing capacity of the segment, and finally reconstruction — restoring length, treating joint contractures and covering soft-tissue defects.

The Ilizarov method is ideal for this because it stabilises the bone without any implant in the infected area and replaces the resulting bone defect with the patient's own bone — by so-called bone transport (bifocal osteosynthesis) or by acute shortening followed by lengthening. Where needed it is combined with vacuum-assisted wound therapy (VAC), an antibiotic-cement-coated intramedullary nail or transfer of the fibula into a tibial defect (fibula pro tibia). Treatment is staged and takes months, but it allows even long-standing osteomyelitis to be permanently cured while preserving the limb.

We speak of delayed union when a fracture has not healed within the average time expected for that bone, and of nonunion (a “false joint”) when it has not healed after twice that period. A fracture of the femoral shaft, for example, usually heals in 3–4 months; if it has not united after 8 months, a nonunion has formed. Bone defects after injuries, surgery or tumours are a particular problem: the fragments are not in contact at all, so healing without surgery is impossible.

A distinction is made between hypertrophic (stiff) nonunions, with little mobility and a partly load-bearing limb — for which several months of stable fixation are sometimes sufficient — and hypotrophic (mobile) nonunions with marked instability, which require surgery at the site of the nonunion: freshening of the bone ends, firm contact between them and reliable fixation.

The Ilizarov frame provides exactly that: measured compression of the fragments that promotes union, alternating compression and distraction that activates regeneration, and at the same time correction of deformity and replacement of shortening or defect with the patient's own bone. This avoids the most common mistake — grafting bone from the pelvis or fibula, which often fails to achieve union and carries the risk of infection and even larger defects. The result is a united, load-bearing and correctly aligned bone.