A locking mechanism (70) for locking a rod (40) in a screw (30) and rod fixation assembly includes a cap (72) having a sidewall (74) and a locking element (90) extending from at least a portion of the sidewall. Locking mechanism cooperates with a receiver component (50) for a spinal fixation rod to lock the rod in the receiver without requiring application of torque. A method of locking a spinal fixation member in a receiver of a screw fixation assembly includes the steps of placing the spinal fixation member into a channel (69) of a receiver, axially advancing a locking cap into the receiver toward the spinal fixation member without application of any torque, and securing the locking cap in a locked position above the spinal fixation member without application of any torque.The locking element may be settled in an annular recess (76) formed in the sidewall, and expand into an annular groove (65) formed in the receiver.
