Callus formation in femur and tibia during leg lengthening: 7 patients examined with DXA.

We examined the callus formation during leg lengthening in 7 achondroplastic patients who underwent 3 bilateral femoral and 4 bilateral tibial lengthenings. Bone mineral content and bone mineral density (BMD) in the lengthened callus space were evaluated every 1 or 2 weeks for 10 weeks after the start of distraction using dual energy X-ray absorptiometry. The mean rate of callus mineralization in femurs (0.64 g/wk) was higher than in tibias (0.22 g/wk). The mean BMD at 10 weeks after the start was 0.35 g/cm2 in the femur and 0.14 g/cm2 in the tibia. Different rates of callus formation in different kinds of long tubular bones have not been reported previously.