Growth of the ulna after repeated bone lengthening in radial longitudinal deficiency.

BACKGROUND

Shortening of the ulna is one of the characteristic features of the radial longitudinal deficiency, which could be treated with repeated bone lengthening. The purpose of this study is to assess the changes in growth rate of the ulna after repeated bone lengthening in radial longitudinal deficiency.

METHODS

Five children (3 boys, 2 girls) who underwent twice bone lengthening of the ulna were reviewed. All patients had unilateral Bayne type IV radial longitudinal deficiency and had received centralization of the ulna previously. Ulnar length was measured on radiographs. Percent length against the normal side was used to measure differences between individuals. Ulnar growth rate was calculated as change in length over time.

RESULTS

Ulnar length was 57.4% of the normal side on average at first visit to our hospitals. Percent length against the normal side became 88.9% immediately after the first lengthening. Then percent length decreased to 70.1% just before the second lengthening and became 101.7% after the second lengthening. Finally, it decreased to 82.9% at the last follow-up. Annual bone growth rate decreased after the first and second lengthening. Especially after the second lengthening, bone growth remarkably decreased. There were no complications except for pin-site infections at the first lengthening, whereas contracture of the elbow joint and callus fracture occurred at the second lengthening.

CONCLUSIONS

Our study showed growth retardation occurred after bone lengthening and that the second lengthening resulted in remarkable growth retardation. We recommend delaying the second lengthening until the skeletal growth stops. Our series is small in number and we must investigate the influence of other factors (age, effect of the previous centralization, the amount of length, etc.). Further investigation will be needed to get firm conclusion.

LEVEL OF EVIDENCE

Level IV.