Product Development and Demonstration of Automated Mandibular Distractor

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DESCRIPTION (provided by applicant): Distraction Osteogenesis is becoming the preferred method to obtain the skeletal expansion necessary to correct congenital and acquired craniomaxillofacial deformities. The procedure consists of an osteotomy at the expansion site and a mechanical device to separate the resulting segments at 1mm/day. Natural osteogenic processes produce new bone to fill the expanding gap. The mandible is often expanded more than 30mm. The mechanical devices used for distracting the mandible have an actuation screw whose end protrudes through the skin or into the mouth. Patients or their caretakers are charged with turning the screw 2-4 times daily. Automating the process will reduce complications associated with poor compliance with the treatment requirements, and continuous motion is known to produce new bone at twice the distraction rate as twice-daily discrete adjustments. These advantages will improve outcomes and reduce the time a device must be implanted. This proposal requests a FastTrack SBIR grant to complete development of a continuous, automated distractor for the mandible. The device uses hydraulic actuation and microprocessor-based closed-loop position control to perform the distraction and can accurately distract along both linear and curvilinear trajectories. No other automated distracters tested to date have these features. Key components include the implanted actuator, a controller that the patient wears externally, and a user interface used by the clinician to monitor and adjust the treatment. Preliminary animal trials showed feasibility of the concept in Yucatan minipigs (n=5). The work proposed here will complete technology development by engineering components that are sufficiently rugged for clinical use and end with a device ready for human trials and product development. Phase I entails developing and demonstrating a position sensor that will function reliably in vivo. Phase II will consist of detailed engineering of the clinician's user interface and engineering a rugged external control unit, and then testing the device in Yucatan minipigs (n=15). The tests will include demonstration of the new device at the rates used with discrete devices, as well as tests at a higher rate to quantify the advantages of continuous distraction. The proposing team is led by Physical Sciences Inc., and includes surgeons in the Department of Oral/Maxillofacial Surgery at the Massachusetts General Hospital and electronic engineers at Embedded Systems Design. The proposal also contains a financial analysis showing expected cost savings achieved through automation, projected revenues, and required investments. PUBLIC HEALTH RELEVANCE: Distraction Osteogenesis is a technique for correcting bone deformities by tapping the body's natural bone- healing functions. It has many advantages over bone grafting to lengthen bone, but current distractors are still plagued by user problems that complicate treatment and sometimes hinder its success. The automated device proposed here will improve outcomes by eliminating patient responsibility, and it will use the biological benefits of continuous motion to reduce the time a device is implanted.