Distraction Osteogenesis of free vascularized fibula flap in reconstructed hemimandible using intraoral distraction device

Since 1989, when Hidalgo first used the free vascularized fibula flap as a new method of mandible reconstruction, this flap has been considered the treatment of choice in the reconstruction of extensive mandibular bone defects (over 6 cm) (Foster et al.,1999) resulting from trauma, infection, or tumour resections (Ferri et al.,1997). Excellent results both functionally and aesthetically (Hidalgo,1989) are obtained thanks to the adequate length (more than 20 cm of bone available), constant geometry (Yim and Wei,1994) and proper dimensions for implant placement (Frodel et al.,1993). Other main features of this flap are: the double periosteal and medullary blood supply which allows multiple osteotomies (Bahr 1998) and correct shaping, an adequate pedicle length, and a very low donor site morbidity. Bone thickness, height and its bicortical structure seem to be ideal for long term implant prosthetic rehabilitation (De Santis et al.,1999). Fibula advantages can become less effective when we deal with complex mandibular defects, which have already undergone previous treatments. Critical soft and hard tissue conditions (scars, fibrosis, bone necrosis, etc) of the recipient site can limit fibula versatility leading to sub-optimal reconstructions. Authors report their experience with two cases of distraction osteogenesis of free vascularized fibula flap performed one year after its transfer to the mandible. The first case involved a vertical distraction osteogenesis of a fibula flap used to reconstruct a hemimandible loss due to a gunshot injury (Nocini,2000). Involving a partial dentate mandible, the reconstruction lead to a vertical bone discrepancy between the flap and the residual dentate stump. To increase fibula bone height restoring the alveolar arch with respect to the occlusal plane, vertical distraction osteogenesis of the flap was performed by means of two intraoral vertical distraction devices. Distraction protocol included: 7 days of latency, a distraction rate of 0.5mm per day, 3 months of stabilization. An 11.0 mm of bone increase was obtained after 22 days. The vertical discrepancy between the fibula and the right dentate hemimandible was completely corrected. Implant surgery was successfully performed. The second case regards a horizontal distraction osteogenesis of a fibula flap used to restore a hemimandible previously treated for a tumor resection, neck dissection, radiotherapy and secondary reconstruction with an iliac crest free graft. Unstretched irradiated tissues limited the mandibular reconstruction with the fibula flap, resulting in mandibular asymmetry. Using an intraoral device, a horizontal distraction osteogenesis of the fibula was applied with the aim of elongating the flap and the fibrous soft tissue of the cheek. After a bone lengthening of 15mm mandibular symmetry was restored. Distraction protocol was the same as previously described except that the stabilization period was 7 week. There was evidence of a slight fracture of the anterior device plate, due to poor scar tissue elasticity and the presence of a cutaneous fistula over the bony gap. The device was therefore removed after the first B-scan image showed bony fusion across the distraction area. Follow up after one year showed mandibular symmetry and a functional improvement of the tongue and of the patient's speech. It is author’s opinion that distraction osteogenesis can play a relevant role in the improvement of functional and aesthetic results of severe mandibular reconstruction.