DESIGN AND FEASIBILITY TESTING OF A NOVEL DEVICE FOR AUTOMATIC DISTRACTION OSTEOGENESIS OF THE MANDIBLE

摘要

Mandibular distraction osteogenesis is a medical procedure for lengthening the mandible bone by stimulating natural bone-healing mechanisms via a mechanical device that exerts a force on the mandible in one or more directions. Many mandibular distraction devices must be placed externally and most rely on the patient to manually actuate the device each day. This project focuses on the design of an automatically actuated, single degree-of-freedom, implantable distraction device that would be minimally visible after installation. Such a device could reduce errors from patient compliance and would be an important first step toward increasing the capability of future devices. A simple motor and leadscrew system was used with a custom designed impact transmission and controller. A test was conducted on a prototype to determine the feasibility of the design and measure the overall system efficiency. The device was able to move the required 70 N load at a rate of about 1 mm per minute. Compared to an equivalent device utilizing a planetary gearhead to amplify the torque, the impact coupling is significantly less efficient. However, the necessary increase in battery size has only a small impact on the total device length. For a system with the same motor and force output, the impact coupling system is shorter than the gearhead-based system due to a 50% reduction in transmission length.