Primary mandibular reconstruction: analysis of 64 cases and evaluation of interface radiation dosimetry on bridging...

The combination of a myocutaneous flap or free cutaneous tissue transfer with a three-dimensional bendable reconstruction plate either of stainless steel or titanium has provided very satisfactory results in primary restoration of mandibular defects following surgical resections in irradiated patients or in those who require postoperative radiotherapy. Sixty-four cases have been treated and evaluated prospectively using this technique. Fifty-three of the patients had the soft-tissue defect restored with a myocutaneous flap, 8 had a free cutaneous tissue flap, 2 were reconstructed with tongue flaps, and 1 closed primarily. The stainless steel plate of the A.O. type was used in 53 cases and the titanium plate system and hollow screws in the other 11 cases. A success rate of 78.9% was found with a median follow-up of 384 days. Thirty of the 64 cases had preoperative irradiation and 15 were treated postoperatively. A plate failure rate of 23% was encountered in those treated with preoperative irradiation and in 20% with those having postoperative irradiation. Forty-nine of the 64 patients or 76.5% experienced no perioperative complications. Five or 7.8% of the complications were minor. Ten patients or 15.6% experienced a major complication with one death due to a myocardial infarct. A radiation dosimetric model was employed using both stainless steel and titanium. The results from this study showed that, when using a parallel pair of beams, an excess dose of irradiation for the lowest energy cobalt-60 is 13%, for 6 mV it is 15%, and for 18 mV it is 20%. The excess tissue dose, both for stainless steel and titanium plates, extends for about 0.2 mm for cobalt-60, 1.1 mm at 6 mV, and for 25 mm at 18 mV. Patients with plates, therefore, can be treated safely with postoperative irradiation using either cobalt-60 or 6-mV energy.