Retraction of transporting bone segment during Ilizarov bone transport

Abstract Objective To investigate the cause and relevant factors of retraction of transporting bone segment (TBS) after removal of its fixator during Ilizarov bone transport. Methods The clinical data of 37 cases with tibial bone defect treated by Ilizarov bone transport, in whom the TBSs were removed before mature of mineralization of the distraction callus and union of the docking site, were analyzed retrospectively. Bivariate correlation was used to analyze relationship between retraction distance of TBS and age, gender, disease course, length of bone defect, times of pre-operation, size of TBS, transport distance, cause of removal, timing and time interval of removal of TBS fixator. Risk factors with significant level were further identified using multivariate linear regression. Results Bivariate correlation analysis showed that the timing of removal was negatively correlated with the retraction distance, the time interval, cause of removal, transport distance and size of TBS were positively correlated with the transport distance(all p<0.05), whereas the age, gender, disease course, length of bone defect and times of pre-operation were not correlated with the transport distance(p>0.05). Multivariate linear regression analysis of the 5 risk factors showed that the timing of removal, transport distance and cause of removal were independent risk factors for the retraction distance (p<0.05), of which, the timing of removal had the greatest impact, followed by the transport distance and cause of removal. The transport distance and time interval were not significant for the retraction (p>0.05). Conclusion The TBS is subjected to distraction force from all the adherent soft tissues during Ilizarov bone transport, which has elastic properties and can make a retraction of TBS if its fixator is removed before mature of mineralization of the distraction callus and union of the docking site. The retraction distance is related to the TBS size, transport distance, timing and time interval of removal of TBS fixator. Importantly, the timing of removal and transport distance are the main factors for the retraction, especially the timing of removal had the greatest impact.