Systems and methods for bone fixation using a plate straddled by a retainer. In an exemplary system, the plate may be an elongated plate configured to be disposed longitudinally on a bone. The retainer may have a body interconnecting a pair of mounting regions. The body may define a recess, and each mounting region may define a first aperture and a second aperture. The retainer may be configured to be mated with the plate to position a section of the plate in the recess such that the retainer straddles the plate. The first apertures may be configured to define through-axes that are tangential to the bone, to enable use with a line including wire and/or cable, and each second aperture may be configured to define a through-axis that extends through opposite sides of the bone while avoiding a medullary canal thereof, to enable use with a threaded fastener.