A surgical instrument including a sleeve through which a tool is inserted andhaving a rotatable housing to facilitate in situ tool exchange and a pair ofhandles rotatable among at least two lockable positions. One handle includes alatching mechanism and the other includes a locking part for one-handedlocking/unlocking. The handles are coupled to drums connected by an innershaft having winglets for locking the handles to each other or to the housingfor rotating the handles about the instrument or relative to each another.Optionally, a knob is coupled to the housing via a bearing shaft having agroove for receiving a movable locking plate, which is movable between lockedand unlocked positions such that when locked the tool received in the sleeveis retained within the instrument and when unlocked the sleeve is separablefrom the remainder of the instrument.
