Reparative osteogenesis in surgical tibial reconstruction assessed with the indirect computer densitometry of radiographic images

Purpose Study the dynamics of reparative process by Ilizarov defect management using indirect computer densotimetry (CD) of the radiographic images. Materials and methods Radiographic study was performed in 17 patients aged from 17 to 63 years old before surgery, during distraction (range 10-90 days), after 30, 60, 90, 120, 150, 200 days of the fixation period in the frame, on the day of frame removal and at follow-up examinations in 1, 2, 3-4, 6-8 months, 1, 2, 3-4, 5-6 years after frame removal. The study of the digitally processed radiographs using the DiaMorph complex was performed. Results The regenerate formation and development of tibiofibular synostosis after 10 distraction days was accompanied by increase of mean optical density of the shadow. Bone remodeling in the interfragmental diastasis and synostosis started in the first fixation month. It manifested in significant decrease of the mean optical density of the areas under study. Before frame removal, all the patients had the distasis filled in with homogenous regenerate that had not complete remodeling typical for bone tissue. At follow-ups after 5-6 years, medium and highly mineralized bone structures prevailed in the studied areas. The portion of low mineralized structures was 4 times less if compared with preoperative values. Conclusions The Ilizarov treatment for tibial defects restores the limb function by formation of a local bony block comprising the interfragmental regenerate and tibiofibular synostosis. Findings of indirect CD provided information about the bone block mineralization. Its density during treatment is associated with the change in the proportions of structures of different mineralization grade. Indirect CD can be used as an additional test for regenerate maturation assessment in order to decide about the time point for Ilizarov apparatus removal.