Distraction Osteogenesis and Its Challenges in Bone Regeneration

Bone is amongst the very few tissues in the human body that possess intrinsic capacity to heal spontaneously following injury. However, beyond a certain critical size defect, bone cannot heal by itself and outside intervention is required. Numerous techniques are available for the management of these defects, including the gold standard autogenous bone grafts, allografts, bone graft substitutes, vascularized fibular bone grafts and systemic administration of anabolic agents. All these techniques, however, do have limitations (Dimitriou et al., 2011; Nauth et al., 2011). Such instances of severe bone loss, whether due to congenital bony deficiencies or acquired causes, pose an immense challenge to the treating physicians, and it is in these cases that distraction osteogenesis could offer a viable and successful alternative to these techniques. Distraction osteogenesis (DO) is a surgical technique in which the intrinsic capacity of bone to regenerate is being harnessed to lengthen bones or to replace large segments of bone. It consists of the application of an external fixator to the affected bone (Figure 1), followed by an osteotomy of the bone and then gradual and controlled distraction is applied to the two bone segments. This controlled distraction, usually by an external fixator, generates new bone within the distracted gap. When the desired lengthening is obtained, distraction is stopped and the external fixator is kept on until the newly formed in the distracted gap is mechanically strong enough to allow removal of the fixator. DO is considered a type of in vivo bone tissue engineering and is superior to other methods of bone regeneration in the management of cases of bone loss, because this technique allows the spontaneous formation of de novo native bone without the need for bone grafts. DO also has the unique ability to regenerate bone and soft tissues simultaneously.