Risk factors associated with docking site complication treated with Ilizarov bone transport technique—a retrospective study of 103 cases
Authors: feng dongwei , zhang yaxin , xu guogang , wu weize , yang fan , ding jianan , jia qiyu , huang xiaoxia , li dong , zhang xu , song yaru , bian rui , jia heping 
Published: May 2023

Abstract
Background: For the treatment of long bone defects of the extremities caused by trauma, infection, tumors, and nonunion, it has been a challenge for clinical orthopedic surgeons. Bone transport technique have become the only way to treat bone defects. However, inevitable docking site complications related to bone transport technique have been reported by many studies. The purpose of this study was to evaluate risk factor of docking site complications of bone transport technique using Ilizarov method in the treatment of bone defect of lower extremity.
Aim: The purpose of this study was to investigate the risk factors associated with docking site complication treated with Ilizarov bone transport technique in the treatment of tibial bone defect.
Methods: The retrospective study including 103 patients who underwent bone transport for the treatment of large bone defect in tibia from October 2012 to October 2019. There were 90 male and 13 females with a mean age of 37 years (range 17-66years). The etiology of bone defect includes high-energy trauma in 25 cases, osteomyelitis in 61 and nonunion in 17. There were 19 cases in the proximal 1/3 of the diaphysis, middle 1/3 in 39 and distal 1/3 in 45 cases. There were 12 limbs in active infected state with sinus and drainage.17 patients suffered soft tissue defect after debridement. The mean bone defect was 6.6cm (range 3-13cm). Single bone transport in 80 cases, and double in 23 cases. The docking time, external fixation time, external fixation index, and docking site complications were documented and analyzed. Univariate analysis and logistic regression analysis were used to analyze the factors that may affect the docking site complication of tibial bone defect treated with Ilizarov bone transport technique. The clinical outcomes were evaluated using Association for the Study and Application of the method of Ilizarov criteria (ASAMI) at last clinical visit.
Results: 103 patients were followed up for (24-48) months, with an average of 27.5 months, The soft tissue were successfully managed by musculocutaneous flap transfer in 17 cases. However, multiple complications occurred in docking site, with an average of 0.53 complications per patient, an average of 0.16 minor complications and 0.38 major complications per patient. Delayed union in 22 cases (21.4%), axial deviation in 19 cases (18.4%) and soft tissue incarceration in 10 cases (9.7%). According to the results of logistic regression analysis, the distance of bone defect (P=0.001,OR=1.976), and distal 1/3 (P=0.01,OR =1.976) were are risk factors for delayed union. Bone defect distance (P< 0.001, OR = 1.981), external fixation time (P = 0.012, OR= 1.017) were risk factors for axial deviation. Soft tissue defect (P=0.047,OR =6.766) and the number previous operation (P=0.001, OR =2.920) were risk factors for soft tissue incarceration. Base on ASAMI bone score, bony result was excellent in 91 patients, good in 7, fair in 3 and poor in 2. The ASAMI functional result was excellent in 67 patients, good in 26, fair in 8, poor in 2.
Conclusion: Ilizarov bone transport technique is a practical and effective method for the treatment of tibial bone defects. However, the incidence of complications at the docking site is high, of which bone defect distance, external fixation time, the number of previous operations, soft tissue defects and the distal 1/3 are risk factors for complications at the docking site, and clinicians should pay attention to them.