Improvement of an ultrasonically controlled growing rod system for spinal implants

To treat scoliosis, a surgery is conducted where a special metal rod is attached inside the human body. Surgery requiring an incision is performed regularly; thus, patients face the risk of infection and the discomfort of surgery multiple times. To solve this problem, a rod system that expands and contracts inside the human body has been developed. However, it is not a structure suitable for being implanted in the human body. The purpose of this research is to develop a new rod system that solves this problem. In this paper, the structure of the new rod suitable for being implanted was shown, and the analysis results using ANSYS were shown. In addition, the results of a verification experiment using a laser displacement meter were shown, indicating the superiority of the new rod.