Effect of elastic intramedullary nailing on lower limb lengthening in acquired shortenings: a prospective study

Introduction Lengthening and correction of limb deformities using Ilizarov external fixation is a frequent standard operation. However, the risk of complications associated with limb lengthening, including superficial or deep infection, contractures, secondary deformity, and fractures after device removal associated with delayed bone consolidation, remains significant. The purpose of the work was to identify the features of bone lengthening with an external fixator in combination with elastic intramedullary nails, titanium or titanium with a composite hydroxyapatite coating, in the conditions of shortening of the lower extremities of acquired etiology. Materials and methods The study included 64 patients, of which 31 patients underwent monofocal lengthening of the femur, 33 patients underwent monofocal lengthening of the tibia. Results The mean external fixation indices (EFIs) of the groups compared for similar lengthening types (femoral or tibial lengthening) did not differ significantly for the types of intramedullary nails implanted. In femoral lengthening, a significant effect on the EFI had the nail type and the ratio of “nail diameter / medullary canal diameter”. The dependence of EFI on the nail type in tibial lengthening was associated with the ratio “nail diameter / internal diameter at the osteotomy site” (p = 0.023). Two-way ANOVA showed that the effect of the nail type on EFI depended on the nail diameter/ internal diameter at osteotomy site ratio in the tibial lengthening group (p = 0.034). Discussion In acquired shortening of the lower extremities, there is no difference in EFI by using titanium elastic nails or intramedullary nails coated with composite hydroxyapatite. The use of a combined technique, in any case, has advantages: it provides good and excellent results without serious complications during lengthening in patients with shortening of acquired etiology. The strong positive correlation between the bone diameter/internal cortical distance ratio at the osteotomy site, coupled with the significant influence of the nail type and nail diameter on EFI, suggests that both factors should be considered together in future studies. Conclusion In shortening of the lower extremities of acquired etiology, the use of a combined bone lengthening technique, comprising an external fixator in combination with elastic intramedullary nailing, provides good and excellent results without serious complications.