Simultaneous multisegmental and multifocal corrections of complex lower limb deformities with a hexapod external fixator

Abstract

Introduction: External fixators are a part of the therapeutic arsenal used in the correction of complex pediatric lower limb deformities. These long iterative procedures, which are commonly performed over several months, strongly impact the lives of these children and their families. To reduce these drawbacks, we perform, whenever possible, a simultaneous multisegmental and/or multifocal correction of these deformities.

Hypothesis: Simultaneous multilevel correction of complex pediatric deformities using external fixators does not result in more complications than sequential corrections.

Materials and methods: Sixteen patients were treated with this hexapod external fixator correction procedure. The mean age was 13.9 years. The corrections involved 12 femurs and 20 tibias, representing 53 osteotomies on 23 limbs. The quality of the correction was assessed by measuring the mechanical axis deviation (MAD), residual limb length discrepancy (RLLD) and a new, specifically defined, criterion called the "angular healing index" (AHI). Complications were assessed according to Lascombes' classification.

Results: The mean MAD went from 30 to 13.5 mm (P<.05) and the mean RLLD from 33.2 to 6.9 mm (P<.05). The mean AHI was 74.1 days/cm (16.7 to 319). The overall complication rate was 13/23 operated limbs or 56.5% (4.3% grade 1, 43.3% grade 2, 9.3% grade 3, and no grade 4).

Discussion: One-stage multilevel corrections of complex pediatric lower limb deformities represent a difficult technical challenge, and any reduction in treatment time must not adversely impact the quality of the results. The rate and severity of complications compared to monofocal/segmental procedures were no higher than that reported in the literature. This study demonstrated the feasibility of multisegmental and multifocal corrections, which reduced the total treatment duration compared to successive corrections, without adversely affecting the result or increasing the complication rate.

Level of evidence: IV; retrospective study.

Keywords: Bone lengthening; External fixator; Ilizarov method; Lower limb deformity.