Feasibility of implants with superelastic behaviour for midface reconstruction

The proper reconstruction of midfacial defects is an ongoing challenge in the field of reconstructive surgery. One of the principal aims of adequate therapeutic and anatomical reconstruction was to guarantee good functional and aesthetical results. In this context, one of the most challenging areas as regards reconstruction of the facial skeleton is the orbit, which refers to the cavity or socket of the skull in which the eye and its appendages are situated. Today, computer-assisted surgery, particularly in combination with patient-specific implants, allows for the reconstruction of complex orbital defects with high precision. In this regard, in commercially available titanium implants, the final shape of the implant has to be determined before insertion; otherwise, not determining the final implant shape can sometimes result in considerable soft-tissue sequelae after implant placement. This problem can be addressed with the use of new material characteristics such as superelasticity in shape-memory alloys. This special type of nickel-titanium-alloy has already found utility in various medical disciplines. In this context, here, we propose to use shape-memory alloys for orbital reconstruction and combine their unique characteristics with the possibility of patient-specific shape-memory alloy implants. We experimented on a broad spectrum of implant geometries and finally achieved a shape that combines sufficient stiffness with superelastic properties. The combination of patient-specific shape and the special physical properties of shape-memory alloy implants can find utility in orbital reconstruction as well as various other surgical reconstructions.