Tibial lengthening using a retrograde magnetically driven intramedullary lengthening device in 10 patients with preexisting ankle and hindfoot fusion

Abstract

Background and purpose — Motorized intramedullary lengthening nails (ILNs) have been developed as an alter- native to external fixators for long bone lengthening. The antegrade approach represents the standard method for tibial ILN insertion. In patients with preexisting ankle and hind- foot fusion a retrograde approach provides an alternative technique that has not been evaluated so far. We report the outcome of this method in 10 patients.

Patients and methods — This retrospective study included 10 patients (mean age 18 years [13–25]) with pre- existing ankle and hindfoot fusion who underwent tibial lengthening with a retrograde ILN (PRECICE). The mean leg length discrepancy (LLD) was 58 mm (36–80). The underlying conditions were congenital (n = 9) and post tumor resection (n = 1). The main outcome measures were: ILN reliability, distraction achieved, distraction index (DIX), time to bone healing, consolidation index (CIX), complica- tions, and functional results.

Results — All patients achieved the goal of lengthening (mean 48 mm [26–80]). Average DIX was 0.6 mm/day (0.5– 0.7) and mean CIX was 44 days/cm (26–60). Delayed con- solidation occurred in 2 patients and healed after ILN dynam- ization or nail exchange with grafting. Toe contractures in 2 other patients were resolved with physiotherapy or tenotomy. Until last follow-up (mean 18 months [12–30]) no true com- plications were encountered, knee motion remained unaf- fected, and full osseous consolidation occurred in all patients.

Interpretation — In patients with LLD and preexisting ankle and hindfoot fusion distal tibial lengthening using a ret- rograde ILN is a reliable alternative to the standard approach with equivalent bone healing potential and low complication rates leaving the knee unaffected.