Abstract: BACKGROUND: The traditional Ilizarov bone transfer technique is used to treat large segmental bone defects of long bones. Although the curative effect is good, due to factors such as the length of wearing external fixation, bone bending deformity, retraction of the extension zone, and refracture, it affects the clinical effect of bone transfer. Biplanar osteotomy and bone transport combined with intramedullary nailing has many advantages. 
OBJECTIVE: To analyze the effect of biplanar osteotomy and bone transport combined with intramedullary nailing in the treatment of large segmental tibial bone defects.
METHODS:  A retrospective analysis was performed on eight patients with large segmental tibial bone defects who were admitted from July 2016 to June 2020, including seven males and one female, with an average age of 39.3 years (33-50 years old). Causes of injury: five cases were injured by traffic accident and three cases were injured by heavy objects. After debridement, the skin defect ranged from 6.5 cm×1.3 cm to 23.1 cm×9.7 cm, with an average of 10.01 cm×5.51 cm. The length of the tibial defect was 6.8-12.1 cm (averagely 9.2 cm). All patients were treated with biplanar osteotomy and bone transport combined with intramedullary nailing for the treatment of large segmental tibial bone defects. In two patients, the bone defect was located in the middle of the tibia. After biplanar osteotomy was performed at the proximal and distal ends of the tibia, intramedullary nails were placed and fixed with locking nails at the distal and proximal ends. The bone fragments at both ends were transported to the middle. In six patients, the bone defect was located at the distal end of the tibia, and a biplanar osteotomy was performed at the proximal end of the tibia. An intramedullary nail was placed and fixed with locking nails at the distal and proximal ends. The proximal two bone fragments were transported anterogradely. The bone migration time, the mineralization time of the traction zone, the healing index, the external fixation time, the external fixation index and the complications of the patients were recorded. Bone healing and limb function were evaluated using the Association for the Study and Application of the Methods of Ilizarov score. 
RESULTS AND CONCLUSION: (1) All eight patients were followed up after operation, and the follow-up time ranged from 19 to 33 months. All patients achieved bone union, and no infection or recurrence occurred during treatment. (2) Bone migration time was 36-62 days, with an average of 50.2 days. Solidification time in the traction area was 267-512 days, with an average of 366.9 days. Healing index was 1.18-1.41 months/cm, with an average of 1.31 months/cm. External fixation time was 5.5-12.5 months, with an average of 8.3 months. External fixation index was 0.73-0.99 months/cm, with an average of 0.86 months/cm. (3) There were three patients with nonunion of the butt joint. (4) According to the Association for the Study and Application of the Methods of Ilizarov score, five patients (62%) were excellent, and three patients (38%) were poor. Functional results were excellent in six cases (75%) and good in two cases (25%). (5) It is concluded that biplanar osteotomy and bone transport combined with intramedullary nailing can significantly shorten the external fixation time, reduce the probability of complications such as needle tract infection, poor alignment, and refracture in the extension area. This is an effective method for the treatment of large segmental tibial bone defects. 

Key words: Ilizarov technique, bone transport, intramedullary nail, circular external fixator, tibial bone defect