Apparatus for loosening in particular cold welded, screws in orthopaedics, having: a housing which has, as viewed in the axial direction of the housing, an elongate, preferably tubular contour, and receives at least one impact element, a plunger, a first spring and a tool receptacle movably mounted therein, wherein the tool receptacle is received in the housing at a front end of the housing, as viewed in the axial direction of the housing, and is held on the housing via a bearing, a closing element is provided at a rear end of the housing opposite, as viewed in the axial direction of the housing, the front end, the impact element and the plunger are connected to one another to form an impact group, the first spring is arranged, as viewed in the axial direction of the housing, between a rear end face of the impact group and a rear end face of the closing element, facing in the direction toward the impact group, characterised in that at least one outer guide rail is provided extending axially in at least a subregion of an outer periphery of the housing, along which outer guide rail at least one preloading element is movably guided along the axial direction of the housing, at least one inner guide rail is provided extending axially in at least a subregion of an inner periphery of the housing, in which inner guide rail an engaging element integrally formed on the impact group is guided, which engaging element is bringable into engagement with the at least one preloading element, the first spring abutting the rear end face of the impact group is preloadable by displacement in the direction toward the end face of the preloading element engaging on the engaging element, by which means the impact group movably guided in the housing is displaced in the direction toward the end face, and on reaching the apex point between the engaging element and the preloading element, the first spring is releasable suddenly in order to transfer a momentum to the tool receptacle by means of the impact group such that the tool receptacle is rotatable via the bearing in the circumferential direction in response to the momentum, so that the impulsive rotary movement thereby generated is transferrable by means of a tool insert received in the tool receptacle to a screw that is to be loosened and which is in connection with the tool insert. a housing which has, as viewed in the axial direction of the housing, an elongate, preferably tubular contour, and receives at least one impact element, a plunger, a first spring and a tool receptacle movably mounted therein, wherein the tool receptacle is received in the housing at a front end of the housing, as viewed in the axial direction of the housing, and is held on the housing via a bearing, a closing element is provided at a rear end of the housing opposite, as viewed in the axial direction of the housing, the front end, the impact element and the plunger are connected to one another to form an impact group, the first spring is arranged, as viewed in the axial direction of the housing, between a rear end face of the impact group and a rear end face of the closing element, facing in the direction toward the impact group, characterised in that at least one outer guide rail is provided extending axially in at least a subregion of an outer periphery of the housing, along which outer guide rail at least one preloading element is movably guided along the axial direction of the housing, at least one inner guide rail is provided extending axially in at least a subregion of an inner periphery of the housing, in which inner guide rail an engaging element integrally formed on the impact group is guided, which engaging element is bringable into engagement with the at least one preloading element, the first spring abutting the rear end face of the impact group is preloadable by displacement in the direction toward the end face of the preloading element engaging on the engaging element, by which means the impact group movably guided in the housing is displaced in the direction toward the end face, and on reaching the apex point between the engaging element and the preloading element, the first spring is releasable suddenly in order to transfer a momentum to the tool receptacle by means of the impact group such that the tool receptacle is rotatable via the bearing in the circumferential direction in response to the momentum, so that the impulsive rotary movement thereby generated is transferrable by means of a tool insert received in the tool receptacle to a screw that is to be loosened and which is in connection with the tool insert.