A stent graft for treating an arterial aneurysm includes loops fixed to struts of stents, wherein the struts define distal and proximal apices. The ends of a ligature can be linked by a wire in a stent graft delivery system that threads anchor loops longitudinally spanning ends of the ligature to maintain the stent in a radially constricted position during delivery to the aneurysm. A delivery system and method for implanting a stent graft prosthesis includes and employs a torque component at a distal end of the stent graft prosthesis, whereby following advancement of the stent graft to a surgical site in a constrained or partially constrained configuration, torque is applied to the torque component to rotationally align the stent graft about a longitudinal axis of the stent graft, followed by deployment of the stent graft in correct rotational alignment. A delivery system and method of its use includes an apex capture assembly, a leg clasp, and a leg stop for capturing a stent graft during orientation and stabilization at an implantation site of a surgical site.