Leg lengthening by callotasis with Orthofix external fixator was performed for seven femoral and three tibial bone segments in ten patients with hemihypertrophy to equalize leg length discrepancies. The mean age at operation was 11 years (range : 6 to 14 years). The mean follow-up after the operation was five years (range : 2 months to 9 years). Of the ten patients, six patients had hemihypertrophy of the non-syndromic overgrowth in one side of the lower limbs, three patients had Klippel-Trnaunay-Weber syndrome, one patient had Beckwith-Wiedmann syndrome. The mean leg length discrepancy before operation was 35mm (range : 23 to 50mm). At follow-up, none of the patients had limp, pain, deformities of bones and limitation of joint motion in the lower limbs. Leg length discrepancies in nine patients were equalized, but one patient had residual leg length discrepancy due to insufficient distraction lengthening by complications. Leg lengthening by callotasis appears to be effective for obtaining equal leg length in patients with hemihypertrophy.
