Orthopaedic assemblies including a tibial component and one of a fixed tibial insert or a rotatable tibial insert. The assemblies may include structure to prevent undesired movement between the tibial component and insert. For example, a retaining tab may be provided on the tibial component that couples to a tab opening on a surface of the tibial insert (either the fixed or rotatable insert). When assembled, the retaining tab may be covered to avoid possible irritation to the patient's surrounding anatomy. The fixed tibial insert may be provided with a tab opening that provides a minimal amount clearance with the retaining tab to help prevent rotation of the fixed tibial insert. The rotatable tibial insert may be provided with a tab opening with more clearance with the retaining tab to allow at least some rotation with the tibial component.
