Femoral Lengthening Over Nails (LON)

Femoral lengthening by distraction osteogenesis with an external fixator involves two phases: the distraction phase to gain length, and the consolidation phase in which the regenerated bone solidifies enough to allow external fixator removal. The consolidation phase is often twice as long or longer as the distraction phase. To decrease the lengthy external fixation treatment time, we developed a method of lengthening over nails (LON) in which an intramedullary (IM) nail is inserted at the time of the initial external fixator application and corticotomy. At the end of distraction, the patient returns to the operating room for locking screw insertion and external fixator removal. The consolidation phase proceeds under protection of the IM nail. We previously reported our first 29 patients (32 femurs) who underwent femoral LON. Average lengthening was 5.8 cm (range, 2–13 cm). We compared this group with a matched-case group that had standard Ilizarov femoral lengthening. LON reduced external fixation treatment time by almost half. The radiographic consolidation index was significantly reduced (p<0.001). Return of knee range-of-motion to normal occurred twice as fast in the LON group. Complications were 1.4 per femur in the LON group (including one deep infection) and 1.9 in the matched-case group. Outcomes were similar in both groups. Since 1990 we have used this technique in more than 100 cases, with a deep infection rate of 5%. All infections have been successfully resolved by IM nail removal, reaming, and antibiotics. The advantages of LON are reduced external fixation time, protection against refracture, and earlier rehabilitation.