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The bone transport technique allows regeneration of the bony tissue in the patient’s limb, in those cases associated with significant bone loss or defect – such as acute fractures, aseptic or infected nonunions, chronic bone infections, tumors, osteomyelitis. Bony regeneration is generally used to fill a gap or missing bone.

With the bone transport technique, an osteotomy (or a corticotomy) is performed in the bone, and an external fixator is used to transport the bone to regenerate and fill the gap. Bone transport can be performed when the bony defect is more than 3cm in the tibia, and 5cm in the femur (classified as intermediate or large defect). Bone transport technique differs from lengthening because, instead of the bone and soft tissues keeping a relatively fixed relationship, the bone slides in the soft tissue envelope similarly to a lift in a lift-shaft.

The method consists of stabilizing the proximal and distal bone segments with screws and/or wires which are held in the two outer external supports of the frame (rings in a circular frame, and clamps in a monolateral frame). A third intermediate ring/clamp is utilized to fix the middle segment. Following the osteotomy, this middle segment is moved gradually to fill the bone defect. The Callotasis technique developed by Prof. De Bastiani at the University of Verona implies the gradual symmetrical distraction of the developing callus following a corticotomy, through the controlled movement along the monolateral external fixator. The biological response to this technique is similar to that described by Ilizarov in association with circular external frames.^{(1) (2)}

One week after the osteotomy, bone transport begins at a rate of ¾ to 1mm per day. Slow transport of one or more bony segments is accomplished by gradually moving a bony segment from one position to another, by distracting the frame connectors. The process of bone formation in the distraction site is known as distraction osteogenesis (first introduced in France in the mid 1980s), and the transport segment moves to fill the bone defect. Attentive monitoring of segmental bone transport should prevent the risk of misalignment, infection and joint deformities.⁽³⁾ Once transport has brought the two bony segments into contact, union may be reached either by compression, or with the resection of bony ends and compression, or bone grafting, or various other ways.

There are several bone transport techniques depending upon the location and size of bone defect.⁽⁴⁾

References 

1. Aldegheri R. Renzi Brivio L et al. 1989. The Callotasis method of Limb Lengthening. Clin Orthop; 241: 137-45.
2. Saleh M, Donnan L. 2000. The technique of Callotasis and its Application to Monofocal Limb Lengthening, in: De Bastiani G. Apley AG, Goldberg AAJ Orthofix External Fixation in Trauma and Orthopaedics. London: Springer.
3. Rigal S, Merloz P et al. 2012. Bone Transport techniques in posttraumatic bone defects. Orthopaedics and Traumatology: Surgery and Research; 98(1): 88-93.
4. Brinker MR, O’Connor P. 2003. The Use of Ilizarov External Fixation Following Failed Internal Fixation. Techniques in Orthopaedics; 17(4):490-505.