A base component for a tibial implant has a lateral compartment and a medial compartment spaced from the lateral compartment defining an open central section therebetween. A connecting portion connects the medial and lateral compartments at an anterior end of the base component which anterior end is located adjacent the anterior tibia. The open central section of the base component intermediate the spaced medial and lateral compartments is open to a posterior end of the base component. The medial and lateral compartments have a bone contacting surface and a superiorly facing surface. The connecting portion has a curved anteriorly facing surface and has a first angled surface extending at an angle from adjacent the anterior end of the base component at a bone contacting surface of the connecting portion superiorly to a posterior end of the connecting portion. The first angled surface defining an anterior end of the open central section.