There are provided orthopedic fixation systems for attachment of a rod to bone. In an embodiment, plate having top and bottom surfaces includes at least one pocket formed through the surfaces to engage an anchor to bone. At least one arm extends from the longitudinal section of the plate. A housing portion has a base configured for slideable engagement with a course defined in the arm to allow selective positioning of the housing portion. The housing defines a passageway for slideable engagement with a rod to allow selective positioning of the rod. A ring has an inner surface for engagement with the housing portion and a lower surface for engagement with the plate. Locking apparatus is configured for engagement with the arm, housing, and rod to allow selective fixation of (1) the housing along the arm and (2) the rod and the housing with respect to one another.
