I-Corps: Ultrasound-Activated Shape Memory Lengthening Device for Orthopedic Applications

The broader impact/commercial potential of this I-Corps project is the development of a medical device for the treatment of bone fractures and deformities in pediatric patients with immature skeletons. Fifteen to thirty percent of all fractures in the pediatric population occur close to the physeal or growth plate. These pediatric patients have reported complications such as the occurrence of uneven bone growth and the need for follow-up surgeries to readjust devices as bones mature.

The proposed technology is a growth-friendly surgical treatment that allows bone union and subsequent lengthening during child growth. The proposed technology is designed to provide adequate forces for the initial stabilization of deformed bone parts, as well as adaptable forces that are required to accommodate the natural tendency for bones to lengthen.

The proposed technology may be extended to fracture fixation in osteoporotic and osteopenic bones where there are significant changes in the porosity, density, and strength of bones over time. Applications of the proposed technology may decrease recovery time and reduce health care costs for the treatment of bone deformities.

This I-Corps project is based on the development of an ultrasound-activated shape memory lengthening device for the treatment of bone fractures and deformities in pediatric patients with immature skeletons. The proposed technology uses ultrasound heating to activate a shape change in the biocompatible material, nitinol, in a non-invasive orthopedic surgical device.

Initial results with the proposed technology have demonstrated that each increase in temperature from ultrasound causes a slight change in the shape of a nitinol device, which may allow a bone to naturally lengthen without force (for growth plate fractures) or force the bones to lengthen (for scoliosis treatments) after the initial stages of the surgery. The ultrasound heating is on the order of a few degrees – well within the range for activating the shape change and still be accommodated by the tissues adjacent to the implant in the body.

The temperature-associated shape change and lengthening may be tailored to suit different bone morphologies or patient requirements. In addition, the proposed device may minimize or eliminate surgeries for readjustment and may reduce complications by 15-50%.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.