Forearm lengthenings are relatively uncommon in children as slight limb length discrepancy is well tolerated. This report describes progressive forearm lengthening using a mono-axial external fixator and an intramedullary guide wire to avoid axis deviation. Ten children are included in the cohort with varying etiologies for limb shortening. Three patients (4 lengthenings) had radial deficiency, 2 patients (4 lengthenings) had Madelung deformity, 1 patient had neonatal septicemia, and 1 patient had multiple hereditary exostosis. Lengthening was performed for esthetic and/or functional reasons. The lengthened bone was the radius in 3 and the ulna in 7. Any angulation was corrected at the time of osteotomy for lengthening (i.e., acute angular correction). Subsequently, an intramedullary guide wire was placed to maintain alignment and a mono-axial lengthening device was applied. Standard distraction lengthening was used followed by a latency period of consolidation.
In contrast to previous reports, no major complications were reported. Three minor complications occurred and all resolved. Mean distraction period was 36 days and mean elongation was 31 mm. No bone axis deviation occurred. Four cases required secondary bone graft (two children had underlying radial deficiency). All patients were improved form an esthetic standpoint. Uniform strength improvement was noted. On the contrary, motion did not increase.
In selected cases, lengthening of a single forearm bone can be accomplished in a safe and efficacious manner. The technique of acute angular correction followed by axial lengthening avoids the complexities of multi-planar devices and angular correction. The addition of an intramedullary wire appears to reduce the complication of angulation during lengthening. As noted by others, the healing rate in children with congenital anomalies is slower and less consistent than post-traumatic deformities.
J Ped Orthop