The influence of screw positions of bone fixation screws on a TMJ implant

Abstract

There are several diseases that can affect the human temporomandibular joint (TMJ), among which we highlight cancer, trauma or fracture, congenital malformation and osteochondritis. TMJ reconstruction was developed to improve mandibular function, reduce disability. Total replacement of the TMJ involves the removal of the "non functional" joint and placing an artificial one. Materials and geometry play an important key role in enhancing the long-term life of the artificial joint. The most applied TMJ implants are rigid plates fixed by screws. This study aims to describe the influence on the strain distribution of screw fixations in TMJ fixations. A 3D finite element model of an intact and an implanted mandible was analyzed. The mandible geometry was obtained through 3D digitalization by a laser scan process. The numerical finite element models and the implants were positioned in a CAD model. The loads were applied including the five most important muscular loads. Numerical results were successfully obtained for the different screw position in the TMJ implant. It was observed that the position of the screws is an important factor for the success of a TMJ implant. The first and last screws present an important function in the TMJ implant fixation to the mandible. © 2010 International Federation for Medical and Biological Engineering.