A modular surgical instrument for knocking out or implanting a prosthesis that defines a prosthesis axis and which has a prosthesis neck includes a tool head with a passthrough for accommodating the prosthesis neck, a locking device for locking the mounted prosthesis neck, and a chuck, which has an axis for transferring a clamping force for the locking device. The passthrough and the chuck are arranged on opposite ends of the tool head relative to a lengthwise direction defined by the axis of the chuck, wherein the passthrough defines a passthrough axis which coincides substantially with the prosthesis neck axis when the prosthesis neck is locked in place. The axis of the chuck is at a distance from a plane defined by the lengthwise direction and the passthrough axis and/or is at a distance from a passthrough lengthwise axis that extends in the lengthwise direction and through the passthrough.