Abstract: A locking mechanism (100) and method of fixation, such as the fixation of a fixation device (104) like a bone screw and of a rod (106) to the spine. The locking mechanism (100) includes a body (102), an insert (108, 308), a rod seat (110, 310) and a set screw. The body (102) includes a bottom portion (114) configured to receive the fixation device (104) and the insert (108, 308) but prevents the insert (108, 308) and fixation device (104) from passing therethrough once the insert (108, 308) and fixation device (104) are engaged. The body (102) further includes a side portion (120) configured to receive the rod (106). Between the rod (106) and the insert (108, 308) is a rod seat (110, 310).