Callus distraction (Ilizarov)

Eric E Johnson, Richard E Buckley

Callus distraction (Ilizarov)

Ilizarov has introduced the technique of gradual callus distraction following corticotomy, in order to restore limb length or to bridge a defect.

  • The great advantage of the Ilizarov method is that while callus distraction helps to correct the length, rotation, and axial alignment of the bone, the soft tissues are distracted as well, thereby minimizing the need for additional reconstruction.

Segmental bone transport using the tubular system.

a) Bone transport system combined with a unilateral external fixator mounted anteriorly on a tibia with distal defect. There is shortening as judged by the overlap of the fibula (1). Resection of the infected nonunion (2) and proximal corticotomy (3). Gradual distraction of 1 mm per day in 4–5 steps.

b) The lengthening (4) compensates the tibial shortening plus the resection distance. Consolidation of the distraction area and at the docking site.

After extensive local resection of the necrotic bone followed by external fixation, a transverse corticotomy is performed away from the defect, preferably close to a metaphysis. The corticotomy is performed either a week after the debridement or— in low-grade infections—simultaneously. Distraction is not commenced for 10 days, but during this time the gap is kept at a distance of 1 mm. Thereafter, the newly formed callus is slowly distracted at a rate of 1 mm per day in 4–5 steps, evenly distributed over 24 hours. Partial weight bearing is usually allowed. The progress of the distraction, callus maturation, and correction of any deformity are monitored by x-rays. When the planned length is reached, weight bearing is gradually increased. Full weight bearing is usually achieved 4–6 months after closure of the defect. As the docking sites have a tendency to delayed union, decortication and bone grafting of these areas may be required or in some cases internal fixation is needed. Bone transport may be long and cumbersome; it therefore requires a commitment by both the patient and the physician. The patient has to be seen regularly during the distraction period, and physiotherapy should be instituted early to mobilize the adjacent joints. In trauma cases, neurological problems due to overstretching of the nerves are rare. Callus distraction over an intramedullary nail may reduce the period of external fixation but is not without hazards, especially in patients who have had previous infections.

Reconstruction of an infected nonunion using bone transport and a circular frame. The infected nonunion and the segment of affected bone have been radically excised. Proximal corticotomy allows bone transport and regeneration. There is a massive hyperemic response in the bone to this treatment and this is believed to be an important factor in the eradication of infection. Final result after docking at the distal site and consolidation of the regenerated bone. The infection was eradicated and varus deformity corrected.