Characteristics of a volume-adjustable compression chamber for transradial prosthetic interface.

In the transradial limb-socket contact interface, the physiological properties and prosthetic operating habits of the residual limb might affect the comfort and functionality of the prosthesis. To enhance the comfort and functionality of the interface, a frame-type socket with four volume-adjustable compression chambers was proposed for the transradial amputation level. The contact pressure of the limb-socket interface was adjusted by the volume changes in the chambers and controlled by a vacuum pump and the corresponding control system. The parameters of the chamber were designed in accordance with the biomechanics of the forearm soft tissue. The chamber with a negative stiffness characteristic was theoretically compared with the chamber with a positive stiffness characteristic. The results showed that the former had a superior performance to the latter in safety and pump performance requirements. A physical model of the transradial frame-type prosthetic interface was also manufactured with four negative stiffness chambers. The experimental results showed that this new prosthetic interface achieved more fitting time and better performance in comfort and functionality than the fixed frame-type socket. This new prosthetic interface with volume-adjustable compression chambers might be an alternative choice for transradial amputees.