Objective To improve the design of the devices used for automatic elasticity distraction osteogenesis, and to pre- liminarily testify their feasibility for clinical application.Methods The internal automatic distraction devices were constructed by three parts, including sinusoid shape memory alloy distractor, reconstructive plate and mini-plate. The animal model of trifocal bone transport reconstruction of canine mandibular mentis was duplicated, in which a 6 cm mandibular mentis segment was re- moved and the transport disc was created by osteotomy in both ends of the mandibular defect. The plateswere used for internal fix- ation and shape reconstruction of the mandible. They also served as transport distraction guidance for the elasticity distractor.Re- sults The new devices could complete bone transport as expected. Regenerated bone segments were formed in two months and both sides of the mandibular body were lengthened. Because of the narrow angle and obstruction from the thick soft tissues in the mentis area, the ultimate symphysis mentalis was not reconstructed.Conclusion The design of the internal elasticity distraction devices showed potential feasibility for clinical practice. But further studies are still needed for better control of the strength and balance of distraction forces.
