[Treatment of limb deformities by the Ilizarov method].

INTRODUCTION

The numerous possibilities for adapting the Ilizarov apparatus allows the progressive correction of complex angular deviations, for which flat apparatus are sometimes difficult to adapt and this report describes our experience using the Ilizarov apparatus to treat axial limb deformities.

MATERIAL AND METHODS

A total of 48 patients (22 girls and 26 boys aged between 2 and 18 years-old) suffering from 58 angular deformities were treated with an Ilizarov device. 40 of the deformities involved bones: 22 tibias, 13 femurs and 6 radius. The remaining 18 deformities involved joints, (17 knees and 1 elbow), 12 were total ankylosis and 6 were flexion contractures. 31 of the cases involved an isolated deformity (16 bones and 16 joints) and 27 were associated with other orthopedic problems. The cause of the deformities were either malformation or infection in most cases. In 39 cases the angular deformities were deviations in a single plane: 13 in two planes and 6 déformities were complex, involving deviation in all three planes. Correction was progressive in 49 cases and immediate in 9 cases. Unequal limb length was treated in 21 cases: 19 of these were caused by bone deformity. The apparatus should cover the entire bone segment to be corrected, from metaphysis to metaphysis. When the deformity is close to a joint, the joint should be bridged so as to stabilize the brace. The fastening of the sides of the deformity involves a maximum of three pins in two different planes. The apparatus must be absolutely rigid so as to avoid any lateral slipping or any movement of the rings relative to the segments of the limbs. The two parts of the apparatus fixed on either side of the deformity should be linked by two groups of three threaded rods with articulations at the ends. When the correction is in a single plane, it is effected around the axis formed by two threaded rods at the point of the deformity. When the deformity is major, 90 degrees or more, the rings tend to shift under the strain, and this leads to a loss of correction and cutaneous problems on the concave face. This may be avoided by fixing threaded rods to the ring, perpendicular to the plane of the deformity. For knee flexion contractures, the rods should be connected to the ring where it crosses the frontal plane passing through the femoral diaphysis.

RESULTS

48 angular deviations were completely corrected. In 10 cases the deformity persisted, but was less than 20 degrees. The deformity reoccurred in 6 of the children: in 3 cases due to the persistence of muscular imbalance, in two cases by assymetric growth, in the other case by plastic deformation on the insufficiently mineralized regenerated bone tissue formed during lengthening. In one case, the common, motor and sensor peroneal nerve was paralyzed, complicating the correction of an anterior dislocation of the knee. The paralysis occurred at the end of the correction and recovery began after 6 months. One 10 year old child, suffering from nail patela syndrome, was left with a completely immobilized elbow after treatment of a webbed, 100 degrees flexion contracture. A total of 9 epiphyseal separations (Salter I type) occurred during the correction of severe deformities, with little or no displacement, all occurred around the knee. These epiphyseal separations did not interfere with the treatment of the angular deviations in three cases, however, advantage was taken of these events to effect the intended lengthening of the bone.

DISCUSSION

The Ilizarov method for correcting joint ankylosis is difficult to perform, and depends on a detailed knowledge of the apparatus and braceing system, and requires rigourous installation of the pins, ring, joints and rods. Whatever the position of the two rings in relation to each other, it is always possible to link them by a system which can be adjusted. This is not possible with other external braces which have only a single plane.