Placement device (600) for implanting a prosthetic device (12) into the body, the prosthetic device (12) being able to expand in radial direction from a compressed state in radial direction to an expanded state in radial direction, the positioning device comprising ( 600): an inflatable balloon (612)； a proximal stop (614) and a distal stop (618) configured to limit the longitudinal movement of the prosthetic device (12) in relation to the balloon (612) during the assembly of the prosthetic device (12) on the balloon (612) in the compressed state in radial direction between the proximal stop (614) and the distal stop (618), the prosthetic device (12) having a proximal end and a distal end； and an outer rod (608) having a lumen and an inner rod (610) extending through the lumen of the outer rod (608), the distal stop (618) being attached to an outer surface of the inner rod (610) , the proximal stop (614) and the distal stop (618) comprising in each case an end portion (628, 630) located inside the balloon (612) and configured to be positioned adjacent to a respective end of the prosthetic device (12 ) when the prosthetic device (12) is compressed radially between the proximal (614) and distal (618) stops, each of the end portions (628, 630) comprising at least one groove (632) extending in longitudinal direction and which allows compressing the end portion (628, 630) of the respective stop (614, 618) in a radial direction to a smaller diameter, characterized in that the proximal stop (614) is configured so that it rests on the end proximal prosthetic device (12) and the distal stop (618) is configured so that it rests on the distal end of the prosthetic device (12), the proximal stop (614) being attached to a distal end of the outer rod (608) and / or attached to an outer surface of the inner rod (610), the groove (632) being configured that extend in the longitudinal direction at each end stop portion (628, 630) so that a balloon inflation fluid flows radially to t
