Insertion of customised exposed titanium implants, without soft tissue cover, for complex orofacial reconstruction

Complex orofacial reconstruction involving multiple surfaces, including bony and cartilaginous structures, without the expectation of substantial soft tissue cover is most frequently needed after severe orofacial trauma or removal of orofacial tumours, but may also be used to treat congenital facial abnormalities. Various materials are used including autologous grafts; tissue-engineered bone; alloplastic materials such as silicone, titanium or hydroxyapatite; and composites (for example, titanium mesh embedded in porous polyethylene).

The traditional method of forming titanium implants for complex orofacial reconstruction is to bend and cut titanium mesh during the operation. Positioning the implant in the appropriate site requires an accurate assessment of shape and fit, and a number of insertion attempts may be necessary before correct implant shape is achieved. In this procedure, computer-aided design and computer-aided manufacturing (CAD‑CAM) techniques are used to create a customised implant before the operation to insert the implant. The aim is to improve both functional and cosmetic outcomes.

The design and construction of custom-made implants can be achieved by a number of different techniques. In most cases, customised implants are designed and manufactured using CT scan data by CAD‑CAM and 3-dimensional printing techniques. In some cases, a model is constructed on which the implant is shaped and made, either directly or indirectly.

With the patient under general anaesthesia the sterilised titanium implant is fixed to adjacent bone using titanium screws. Precise details of the operation will depend on where the implant is to be used and the integrity of surrounding structures.

A case series of 14 patients who had undergone reconstruction procedures following removal of head and neck tumours reported that the maxilla, hemimandible and nose were successfully reconstructed without needing to raise flaps for coverage. Attempts to reconstruct the subtotal mandible in 2 patients failed because of lack of soft tissue adherence. Both patients underwent further conventional procedures after the implants were removed.

In the case series of 14 patients, appearance was described as excellent in 3 patients (details of appearance were not described for the remaining patients). After 2 years of follow-up, all patients remained disease-free and had an acceptable quality of life.

The specialist advisers listed key efficacy outcomes as reduced operating time, reduced morbidity, long-term implant retention rates, fixation (screw) removal rates and survival rates (for patients with cancer).

Ulceration through the skin of titanium-coated hollow screw reconstruction plate (THORP) implants was reported in all patients with buccal placement of plates in the case series of 14 patients. Eight patients had been treated using THORP but it was not reported how many of them had buccal placement of the implant. It was noted that 1 patient was treated by fitting an acrylic cover plate over the exposed section of the THORP implant. Case reports described unintentional implant exposure in 2 patients that occurred after insertion of large titanium implants for nasal reconstruction. Both patients needed a number of additional procedures.

Infection due to methicillin-resistant Staphylococcus aureus (MRSA) resulting in removal of the implant was reported in 1 patient in the case series of 14 patients.

Fistulae were reported in 4 patients in the case series of 14 patients. Two of the fistulae were closed with relatively simple flap procedures, and a third was closed using adjuvant hyperbaric oxygen therapy. The fourth fistula was found after 2 years at the site of one of the rivet heads on the THORP implant. This orocervical fistula failed to close after 4 flap procedures and hyperbaric oxygen therapy; eventually titanium chain mail with a solid titanium diaphragm was used to close it.

The specialist advisers listed theoretical adverse events as recurrent infection, bone infection, possible septicaemia, externalisation, bone resorption, loosening of the implant, poor aesthetics and failure of the prosthesis.