Abstract: An instrument for manipulating, detachably holding and placing an insert portion of a joint socket prosthesis into an outer shell of a said prosthesis. The instrument includes a handle and a holding tool. The holding tool includes two or more grasping claws which extend radially from the longitudinal axis of the handle over the insert, and serve to engage the insert to the holding tool. The handle is elongated and slideably positioned within a longitudinal bore or hole in the holding tool and typically includes a plunger. The insert is released when an operator causes the handle to slide within the holding tool towards the insert with sufficient force to disengage the insert from the grasping claws.