The results and complications of femoral lengthening over an intramedullary nail with a external fixator in patients with limb length discrepancy were retrospectively reviewed.

After lengthening 22 femoral segments, all patients were followed-up for a mean of 3.2 years (range, 2 to 5.2 years). They ranged in age from 13 to 35 years (average age, 22.2 years) at the time of the index procedure. The mean lengthening was 5 cm (2.7 to 8.1 cm), and the external fixator was removed after a median 135.9 days (range, 59 to 210 days). The mean external fixation index was 23.8 days/cm of lengthening (range, 11.1 to 34.7 days/cm of lengthening).

Nineteen patients achieved the length of their pre-operative goal. However, there were 3 failures with osteomyelitis and the removal of the nail, which had a past history of infection or open trauma. There were 4 knee joint complications when the lengthening was over 20%. These included three cases of a patella subluxation and one case of a posterior knee subluxation. In the other complications, there was one case of a collapse in the lengthened segment with a breakage of the locking screws.

Although lengthening over a nail can reduce the duration of external fixation, caution is needed in order to prevent complications.