[Progressive forearm lengthening in children: 14 cases].

PURPOSE OF THE STUDY

There are few indications for forearm lengthening in children. Several techniques have been proposed. We report our experience with progressive lengthening of the forearm in children using a unilateral axial external fixator and an improved technique consisting in initial insertion of an intramedullary guide wire.

MATERIAL AND METHODS

Since 1990, we performed 14 forearm lengthenings in 9 children. Radial agenesia (5 forearms in 4 children), and hereditary multiple exostosis (3 forearms in 2 children) were the predominant causes. The ulna was involved in 9 cases and the radius in 5. Age at initiation of the lengthening procedure ranged from 4.5 to 14.8 years (mean 9.9). The lengthening technique consisted in a transverse subperiosteal osteotomy of the bone shaft then progressive distraction with a unilateral axial external fixator. When axial deviation had to be corrected, we used a subtraction osteotomy. In our last 10 cases, we inserted an intramedullary guide wire in the lengthened bone. The external fixation was left in place throughout the lengthening procedure and until complete bone healing. Serial radiographs were used to assess bone healing, the degree of lengthening achieved and any axial deviation at the end of lengthening.

RESULTS

All 14 forearms were reviewed at a mean 50.6 months. Mean lengthening was 26.4 mm (range 10 - 52 mm). There were no nerve or vessel complications. In one case, reducible claw finger completely regressed after temporary interruption of the lengthening. There were 6 cases of late healing requiring a secondary bone graft. The healing index was 61.9 days per cm gained length. There were 3 cases with an axial deviation at the end of lengthening.

DISCUSSION

Insertion of a guide wire in the bone being lengthened reduced the risk of late healing compared with lengthening procedures without a guide wire, avoiding axial deviation. In addition, this technique led to more rapid bone healing so the fixator could be removed earlier. We have found this method to be easier to perform on a normally axed segment. This would require an initial subtraction osteotomy for prior alignment.

CONCLUSION

Forearm lengthening is a difficult procedure. Use of an intramedullary guide wire associated with an external fixation and an initial osteotomy for axial correction when needed and possibly stabilization of the wrist is an important contribution, particularly for malformed forearms.