A catheter assembly comprising: a catheter shaft having a leading end and a trailing end and comprising a main lumen extending between the leading end and the trailing end; an expandable implant positioned onto the catheter shaft at the leading end of the catheter shaft, the expandable implant having a proximal end and a distal end, a collapsed configuration for endoluminal delivery of the expandable implant to a treatment site, and an expanded configuration having a diameter larger than the diameter of the collapsed configuration,; and two steering lines that traverse and interact with a surface of the expandable implant in a pattern which facilitates controllable bending of the expandable implant, wherein the steering lines traverse the surface of expandable implant such that, across a significant portion of the expandable implant, both steering lines are parallel to and in close proximity with each other, wherein the steering lines are woven through the surface of the expandable implant, and wherein the expandable implant is an expandable stent graft, comprising a stent and a graft member and the steering lines are woven through the surface of the expandable implant by either: - passing between a first apex of the stent and an outer wall of the graft member, extending through the outer wall of the graft member, reentering the graft member and passing between a third apex of the stent and the outer wall of the graft member; or - passing between the outside wall of the graft member and the stent; or - passing from an inner wall of the graft member, through to an outer wall of the graft member between a first apex and a second apex of the stent, back through to the outer wall of the graft member, and back through to the inner wall of the graft member between the third apex and a fourth apex of the stent. a catheter shaft having a leading end and a trailing end and comprising a main lumen extending between the leading end and the trailing end; an expandable implant positioned onto the catheter shaft at the leading end of the catheter shaft, the expandable implant having a proximal end and a distal end, a collapsed configuration for endoluminal delivery of the expandable implant to a treatment site, and an expanded configuration having a diameter larger than the diameter of the collapsed configuration,; and two steering lines that traverse and interact with a surface of the expandable implant in a pattern which facilitates controllable bending of the expandable implant, wherein the steering lines traverse the surface of expandable implant such that, across a significant portion of the expandable implant, both steering lines are parallel to and in close proximity with each other, wherein the steering lines are woven through the surface of the expandable implant, and wherein the expandable implant is an expandable stent graft, comprising a stent and a graft member and the steering lines are woven through the surface of the expandable implant by either: - passing between a first apex of the stent and an outer wall of the graft member, extending through the outer wall of the graft member, reentering the graft member and passing between a third apex of the stent and the outer wall of the graft member; or - passing between the outside wall of the graft member and the stent; or - passing from an inner wall of the graft member, through to an outer wall of the graft member between a first apex and a second apex of the stent, back through to the outer wall of the graft member, and back through to the inner wall of the graft member between the third apex and a fourth apex of the stent. - passing between a first apex of the stent and an outer wall of the graft member, extending through the outer wall of the graft member, reentering the graft member and passing between a third apex of the stent and the outer wall of the graft member; or - passing between the outside wall of the graft member and the stent; or - passing from an inner wall of the graft member, through to an outer wall of the graft member between a first apex and a second apex of the stent, back through to the outer wall of the graft member, and back through to the inner wall of the graft member between the third apex and a fourth apex of the stent.