The present invention relates to a locking mechanism and method of fixation, such as the fixation of a fixation device like a bone screw and of a stabilization device like a rod to the spine. The locking mechanism includes a seat and a locking element. The seat includes a bottom portion configured to receive the fixation device such that a socket of the bottom portion engages part of the fixation device and prevents the fixation device from passing entirely therethrough. The seat further includes a side portion configured to receive the stabilization device and a locking element. The locking element, when fully engaged with the side portion of the seat, causes locking of the relative positions of the fixation device and the stabilization device.