Orthopedic fixation devices, assemblies, and methods. The orthopedic fixation devices may comprise coupling elements, hook components, and/or bone fasteners. The bone fastener may be loaded into the coupling element through the bottom of a bore in the coupling element. The orthopedic fixation devices may include modular locking clamp assemblies that can be fixed onto fasteners that are already implanted in bone. The modular locking clamp assemblies can include polyaxial locking clamp assemblies, as well as monoaxial locking clamp assemblies. The hook components may include a female hook component slidably coupled to a male hook component.