Introduction and Aims: We evaluated the incidence, cause, predisposing factors, and treatment outcomes of fractures associated with limb lengthening. Our aim was to improve the prevention and treatment of these fractures.

Method: We studied 70 patients with 80 fractures retrospectively identified from a database of all patients who had undergone limb lengthening at our institution between 1987 and 1999. Fractures were analysed according to bone fractured, classification of fracture, timing, diagnostic group, treatment, and residual deformity. Treatment of fractures was individualised for each patient according to the specifics of fracture occurrence. A residual deformity was defined as shortening > 1cm or angulation of clinical significance > six degrees.

Results: Eighty fractures occurred with 986 lengthenings in 650 patients, yielding an overall fracture rate of 8.1%. Seventy-four percent of fractures occurred in regenerate bone or at the host-regenerate junction. Eighty-one percent of fractures occurred out of frame. Four percent occurred at time of frame removal, 16% with the frame still in situ. Majority of fractures sustained out of frame (84%) were through regenerate bone; majority in frame (85%) were through non-regenerate regions, 69% of these through a pinhole. Patients with dysplasia and those undergoing lengthening because of congenital syndromes had a higher incidence of fracture (11% and 19%, respectively) and a higher incidence of residual deformity (RD) (47% and 45%, respectively) than did the rest of the patient population. Overall incidence of RD was 38%. Rate of RD was 23% for fractures occurring in frame, 67% at removal time, and 40% for those sustained after removal.

Conclusion: Majority of fractures occur out of frame through regenerate bone. Most non-regenerate fractures occur at pin site. Operatively and non-operatively treated fractures had similar rates and magnitudes of residual deformity. Congenital and dysplastic had higher rates than post-traumatic (possibly more ambitious surgical goals, smaller bone diameter, more limiting soft tissues).