Functional outcome following bone transport reconstruction of distal tibial defects.

BACKGROUND: Little has been written about the functional outcome of patients treated with bone transport to reconstruct a distal tibial defect. The aim of this study was to investigate the functional capabilities of patients who had undergone reconstruction with distraction osteogenesis for the treatment of a distal tibial defect in one lower limb. METHODS: At least eighteen months after completion of treatment, eight patients who had no pain and were able to walk and climb stairs without difficulty performed isometric ankle plantar flexion maximum voluntary contractions while the electromyographic activity of the tibialis anterior and triceps surae muscles was simultaneously recorded. Seven of the patients also underwent gait analysis. Data for the involved limb were compared with those collected for the contralateral limb. RESULTS: During gait, stance time (p = 0.01), the plantar flexion angular displacement and peak moment developed during the second half of stance (p < 0.046), and the amount of ankle power generated (p = 0.02) were significantly decreased in the involved limb compared with the contralateral limb. Similar decreases were observed in the plantar flexion (p = 0.01) and dorsiflexion (p = 0.01) maximum voluntary contractions and the corresponding electromyographic activity (p = 0.01). CONCLUSIONS: These results suggest that adaptive changes had occurred at the level of the transported muscles, which affected both routine and maximal effort capabilities. These findings contribute to our understanding of the functional limitations of patients who have undergone bone transport with its obligatory shortening of muscle length.

Cross-sectional anatomy in postdistraction osteogenesis tibia.

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.