A flexible malleable shaft is made up of a plurality of prismatic shaft elements adjacent one another. A recess is formed in a proximal end of each shaft element, the recess defined along a transverse axis. A protrusion is formed in a distal end of each shaft element, the protrusion defined along a transverse...http://www.google.co.uk/patents/US20050131457?utm_source=gb-gplus-sharePatent US20050131457 - Variable stiffness shaft
