HIGH-FREQUENCY PROGRESSIVE LENGTHENING FOR CONGENITAL LOWER LIMB LENGTH DISCREPANCY IN CHILDREN

Abstract

Purpose of the study: A population of 154 patients was studied to determine the advantages of continuous lengthening for congenital lower limb length discrepancy (LLLD).

Material and methods: In a first series, we analyzed 80 progressive lengthenings using the standard rhythm (1 mm daily, 4 lenghtenings per day). In a second series (74 lengthenings) a high-frequency rhythm was used (1 mm daily, 60 lengthenings per day). Mean patient age was 10.3 years. Bone regeneration was not stimulated (either by extemporaneous compression or stable elastic centromedullary nailing) in this population. The automatic lengthening fixator was composed of the two standard pieces of the Ilizarov system and complementary blocks with self-propelled traction rods. Besides simplifying the lengthening procedure, these rods allowed high-frequency correction of associated deformities.

Results: Femoral gain was 52 mm on average. For the tibia, the gain was 48 mm on average. For ordinary monosegmentary lengthenings, the healing index was 27.6 d/cm for the femur and 36.0 d/cm for the tibia. For multisegmentary lengthenings with the standard rhythm, the overall healing index was 20.3 d/cm. For patients with high-frequency lengthening, time to healing was shorter. The radiological findings showed the presence of significant bone regeneration which was never inhibited. For monosegmentary lengthenings, the healing index was 22.9 d/cm for the femur and 27.1 d/cm for the tibia. For the multisegmentary high-frequency lengthenings, the overall healing index was 14.7 d/cm. The difference between standard and high-frequency lengthening was significant. In the first series, motion of the adjacent joints was recovered within 12 to 18 months after removal of the fixator. The patients remained in the reclining position during the high-frequency lengthenings and very satisfactory results (complete recovery of joint motion) were obtained 12 months after removing the fixator. In addition, in the second series, there was no impact on the spontaneous growth of the lengthened segments.

Discussion and conclusion: Congenital LLLD is generally more difficult to treat than acquired conditions (Damsin et al., Grill et al., Glorion Ch.). The rate of complications remains significant, particularly concerning healing complications and stiffness in the adjacent joints. Our clinical results prove that high-frequency lengthening provides optimal conditions for tissue regeneration. For children with congenital LLLD, continuous lengthening shortens the delay to healing and avoids stiffness in the adjacent joints.