Background: Although the early period of distraction osteogenesis has been extensively investigated, there are few data describing the appearance of medium-term bone regeneration.
Method: We investigated 10 adults with magnetic resonance imaging scans. Seven of them underwent bone transport, and three had tibial lengthening. The mean follow-up was 28 months after removal of the external fixator. The values were compared with those of the contralateral tibia, which acted as a control.
Results: All of the cases with bone transport had an increase in the volume of the whole tibia of 15.3%-50.8%. The diameters of the regenerated segments increased significantly (P < 0.0001) in all cases. The mean signal intensity in the regenerate decreased significantly in seven cases (P < 0.0001), which suggested a rise in the content of unhydrated tissue, such as bone and collagen. The cross-sectional area of the transported segment increased in all cases (P < 0.01). Finally, in the patients who underwent bone transport, the docking site was seen to be obstructed by unhydrated tissue.
Conclusions: Contrary to previous claims, the postdistraction osteogenesis of tibia consists of areas with potentially different biomechanical properties. Recognition of these changes is essential not only for appropriate preoperative counseling but also for considering treatment modalities in case of fracture.