New Design of NT Memory Connector for fractures and nonunion of distal radius

Objective   To find a new method for the management of fractures and nonunion on distal radius. Methods   According to the anatomical feature, mechanism of fracture and stress sustained on the fracture site of distal radius, a new type of nitinol shape memory alloy connector was designed by taking the advantage of its special mechanics action. The biomechanics test included photoelasticity, electrometric method and three dimensional finite element analyses. In clinical applications, 25 cases were treated by the procedure, of which 5 cases were fresh fractures of distal radius and 20 cases nonunion. The duration of postoperative follow-up was from 6 moths to 2 years (1.3 years on average).   Results The biomechanics study showed that the connector was characteristic of good anti-fatigue and reuse. The initiative memorial bone holding and  longitudinal compressive forces were 98.40N~125.05N and 152N~196N correspondingly for maintaining axial stability. All the cases had primary healing without infection, angulationer and dislocation. Fracture line disappeared 9~14 weeks later postoperatively.  Conclusion The newly designed NT memory device that matches optimally the anatomy of the distal radius. It not only can maintained longitudinal compressive force continuously, but also has efficacious fixation effect with anti-shearing, bending and distracting stress. It can shorten the duration of bone healing and improve the healing quality of bone.