Controlled injection of bone cement for percutaneous vertebroplasty.

In this article, assistance to bone cement in- jection is studied, with a focus on vertebroplasty, a procedure dedicated to the treatment of painful vertebral compression fractures. A robotic system that can remotely be operated at pressures up to 140 bar is presented. It is specifically designed to improve cement polymerization control, combining a cold passive exchanger that slows down the cement curing in the syringe, and an active exchanger that controls the injected cement temperature. The cement remote injection uses a rate control teleoperation strategy, particularly well suited for very slow injection speeds. During the injection, force feedback is rendered to the radiologist to help monitor the cement viscosity increase. A first assessment in laboratory conditions has been achieved to quantify the performance of the thermal exchanger. Then, cadaver experiments have been performed to illustrate the satisfactory operation of the whole system.