Abstract: An apparatus comprising two rasping halves conforming generally to the shape of the bone cavity to be produced, and a drive mechanism for reciprocating both rasping halves counter to each other in an axial direction. A rotary cutting tool in front of the rasping halves prepares the bone cavity to receive the rasping halves. A flexible drive shaft for the cutting tool extends between the rasping halves and rotatably within a drive shaft for the rasping halves. The latter drive shaft has a slot oriented at an angle to the axis of rotation of the drive shaft, and a pin projects from each rasping half into the slot, the pins being located 180.degree. apart. A bushing guides the movement of the rasping halves, and the pin from each rasping half extending through a slot in a housing for their drive shaft prevents twisting of the rasping halves.