A rod extension for extending a fusion construct allows a surgeon to connect a stabilization rod implant to at least a portion of a patient's spine, and also to connect the stabilization rod implant to an existing implant that has been previously installed in the patient. The existing fusion implant typically includes at least one existing pedicle screw, at least one existing rod, and at least one existing connector interconnecting the existing pedicle screw to the existing rod. The extension implant comprises a rod, an offset beam connected to the rod, and a clamp interconnected to the offset beam, wherein the clamp can be secured to the existing rod, thereby extending the fusion construct.