Abstract: A device for repair of intervertebral discs and cartilages in articular joints includes a catheter for inserting through a cannula, the catheter having a distal end and a proximal end and a lumen extending longitudinally therethrough. An expandable balloon may optionally be detachably attached to the catheter near the distal end. The proximal end of the catheter is coupled to an injector that holds a supply of a thermoplastic elastomer material at a predetermined elevated temperature sufficiently high to maintain the thermoplastic elastomer at a liquid state. The device allows a thermoplastic elastomer material to be injected into the intervertegral disc space or the articular joint space as a replacement prosthetic for the disc's nucleus pulposus or the joint's cartilage. This procedure is carried out percutaneously through the cannula.