Implantable medical endoprosthesis delivery system

An implantable medical endoprosthesis delivery system, comprising:

• a delivery catheter;
• a delivery member at least partially disposed within the delivery catheter;
• a first bumper circumferentially disposed around and attached to the delivery member;
• a second bumper circumferentially disposed around and attached to the delivery member;
• and
• an endoprosthesis circumferentially disposed around the delivery member and longitudinally between the first bumper and the second bumper, wherein the first and second bumpers limit longitudinal movement of the endoprosthesis relative to the delivery member such that, while the endoprosthesis is disposed in the delivery catheter,
• the endoprosthesis remains substantially stationary in a longitudinal direction with respect to the delivery member when the delivery catheter moves proximally or distally with respect to the delivery member, and
• the endoprosthesis remains substantially stationary in a longitudinal direction with respect to the delivery member when the delivery member moves proximally or distally, wherein the first and second bumpers each comprise a helical coil, and
• wherein, while the endoprosthesis is disposed in the delivery catheter, the endoprosthesis is freely rotatable around the delivery member.