Mandibular Bone transport Reconstruction Plate

DESCRIPTION (provided by applicant): Surgical excision of hard and soft tissues of the head and neck or high impact trauma can lead to lead to major tissue deficits. Reconstruction of the lower jaw typically involves bone, gingiva, and teeth. Current mandibular distraction devices are used in combination with reconstruction plates, but while the reconstruction plates take the contour of the jaw, the distraction devices have a linear vector. The devices also have a limited distraction distance, producing short segments of straight bone and so cannot accommodate large deficits with a single procedure. The size of the combined apparatus makes it impossible to move dentate bone segments. Extra-oral devices function both as external fixator and bone-transport distraction devices, with which it is possible to re-build the mandibular parasymphysis and chin. However, the newly formed mandible is retruded due to soft tissue pressure and normal curvature of the mandible is not achieved. The objective of Phase I of this proposal was to build and test a prototype of an intra-oral mandibular distraction device in which the reconstruction plate, advancing mechanism and bone transport device are combined into a single unit. The prototype was built and shown to be mechanically robust, easy to place and use, and able to successfully transport a dentate bone segment across a 2cm bony gap in a live goat model. The objective of Phase II of this proposal is to build and test the second and third generations of this device. These devices will enable transport of dentate bone segments over large curved distances including the midline of the jaw, and prevent the inhibition of form by soft tissue pressure. The purpose of these devices is to allow immediate reconstruction of mandibular bone following surgical excision, eliminating the need for bone grafting or secondary reconstruction. The advantage of the devices is that they will enable us to regain the mechanical integrity and shape of the original mandible, and allow appropriate occlusion to occur when implants are placed in the reconstructed bone. This will be done without adding to the difficulty, duration, or complication of surgeries. A critical feature of the devices is that they are not limited by the size, shape, or location of the bone gap and because of the low position of the device; the transport disc can safely carry viable teeth without injuring the roots during fixation. The "check-point osteotomy" technique will make it possible for the first time to regain the normal curvature or the original mandible, and preserve the original lower facial dimensions as the traction force exerted by the soft tissue over the transport disc is rigidly shielded by the transport plate.