A medical instrument handle assembly (10), for holding a medical instrument configured for preparing a bone to receive an implant, includes: a housing (14) including a housing pin (38) an elongate arm (18) including a proximal end (47) a lever subassembly (20) including a lever body (52) and a lever latch (54), the lever body being pivotally connected to the proximal end of the elongate arm, the lever body and the lever latch being pivotally connected to one another and thereby being selectively positionable relative to one another between a first position and a second position, the first position being when the lever body and the lever latch are clamped about the housing pin, the second position being when the lever body and the lever latch are unclamped relative to the housing pin.