Orthopaedic instrument with an integrated gear transmission of 1:2 for reduction of the insertion time of bone screws. The medical adapter with internal transmission gear enables the doubling of insertion speed for bone screws by applying single speed insertion at the handle. To allow a reduction of gear transmission from 1:2 to 1:1 while insertion procedure the gearing can be locked by pushing a slide switch. Quick couplings on both ends of the housing enable a safe and simple adaption between the shank of the screw driver and the standard handle. To minimze weight the instrument housing is made out of a light metal alloy coated with a scratch resistant and non-corroding layer. To garantee safe and effective cleanliness in the hospital the housing can be pulled completely off by pressing a push button.