A locking mechanism assembly to allow locking of a fastener in an orthopedic implant having its axis at a variable angle relative to the axis of threaded through opening in the implant. The assembly includes a locking insert, having threads which mates with the threads of the through opening and which includes a smooth opening that forms a torque driving recess and an annular flange. A fixator has a head portion with external threads of a harder material than that which forms the through opening so that the threads of the fixator will deform the insert to lock the fixator in a desired position relative to the plate.