Αντικατάσταση εξωτερικής οστεοσύνθεσης από ενδομυελικό ήλο στη φάση σταθεροποίησης της οστικής επιμήκυνσης

Abstract

The purpose of the study is to evaluate the effectiveness of external fixation exchange by intramedullary nailing during consolidation phase following callus distraction phase in distraction osteogenesis. In 12 skeletally mature sheep, divided in two groups (group A and group B), tibial shaft osteotomy and 2cm gradual callus distraction using Ilizarov external fixator was performed. In group A, Ilizarov fixator was removed immediately after lengthening completion and static unreamed intramedullary nail was inserted. In group B (control group), Ilizarov device remained during consolidation phase (according to the usual technique). Formatted callus was studied by radiographs, ultrasonograms, triplex and digital angiograms. All animals were sacrificed 70 days after osteotomy and bone specimens, were evaluated by computed tomograms and histopathologic examination. In group A, all animals successfully tolerated intramedullary nailing attaining limb alignment and formatted mature callus (which had started the remodeling phase), before being sacrificed. In group B, 5/6 formatted mature callus, 3 had serious axis disorder, 3 persistent superficial pin-track infections and 1 deep infection. The method decreases the total duration of external fixation, limits joint stiffness, pin-track infections and axial deformities, and provides protection against re-fracture. We also evaluated the outcome in 30 patients (33 segments) with secondary intramedullary nailing during the consolidation phase after callus distraction using an external device. Docking site nonunion (17 patients), angular deformity or fracture of the lengthened area (8 patients), or intolerance to the external device (5 patients), in combination or not with a delayed distracted callus maturation, were the main reasons for nailing. The average follow-up time was 4 (2-12 years). Intramedullary infection after nailing occurred in 1 case, and slight callus length loss in 5 cases. Failure of union at the docking site with nail breakage occurred in 1 case. In the other patients, consolidation in the lengthened callus area as well as union at the docking site was achieved average 6 months after nailing. Secondary intramedullary nailing during the consolidation phase of distraction osteogenesis is a treatment option for intolerance of the external fixator, delayed callus maturation or docking site nonunion, reducing the prolonged use of the external fixator.