A tibial prosthesis for replacing at least part of a natural knee of a body, the body defining a sagittal plane which centrally separates the body into right and left halves, said tibial prosthesis comprising: a bearing component (104F, 104I) comprising: at least one concave articulating surface; a distal surface (124F, 124I) opposite said concave articulating surface; and a notch (160F, 160I) formed in said distal surface, said notch defining a longitudinal axis, said longitudinal axis defining an offset axis angle relative to the sagittal plane, said offset axis angle (α) ranging from greater than zero degrees to about 90 degrees; and a tibial tray (102F, 102I) comprising: a support surface (114F, 114I) capable of supporting said bearing component, said support surface having a lateral edge (112F, 112I) and a medial edge opposite (110F, 110I) said lateral edge, and a two-pronged boss (146F, 146I) having a longitudinal axis, said longitudinal axis angled with respect to the sagittal plane, said two-prong boss comprising: a lateral jaw (157F, 157I) having an anterior end, a medial jaw (155F, 155I) having an anterior end, and said anterior end of said lateral jaw spaced apart from said anterior end of said medial jaw, said two-pronged boss lockingly engageable with said notch along said offset axis angle to lock said tibial tray to said bearing component. a bearing component (104F, 104I) comprising: at least one concave articulating surface; a distal surface (124F, 124I) opposite said concave articulating surface; and at least one concave articulating surface; a distal surface (124F, 124I) opposite said concave articulating surface; and a notch (160F, 160I) formed in said distal surface, said notch defining a longitudinal axis, said longitudinal axis defining an offset axis angle relative to the sagittal plane, said offset axis angle (α) ranging from greater than zero degrees to about 90 degrees; and a tibial tray (102F, 102I) comprising: a support surface (114F, 114I) capable of supporting said bearing component, said support surface having a lateral edge (112F, 112I) and a medial edge opposite (110F, 110I) said lateral edge, and a two-pronged boss (146F, 146I) having a longitudinal axis, said longitudinal axis angled with respect to the sagittal plane, said two-prong boss comprising: a lateral jaw (157F, 157I) having an anterior end, a medial jaw (155F, 155I) having an anterior end, and said anterior end of said lateral jaw spaced apart from said anterior end of said medial jaw, said two-pronged boss lockingly engageable with said notch along said offset axis angle to lock said tibial tray to said bearing component. a support surface (114F, 114I) capable of supporting said bearing component, said support surface having a lateral edge (112F, 112I) and a medial edge opposite (110F, 110I) said lateral edge, and a two-pronged boss (146F, 146I) having a longitudinal axis, said longitudinal axis angled with respect to the sagittal plane, said two-prong boss comprising: a lateral jaw (157F, 157I) having an anterior end, a medial jaw (155F, 155I) having an anterior end, and said anterior end of said lateral jaw spaced apart from said anterior end of said medial jaw, said two-pronged boss lockingly engageable with said notch along said offset axis angle to lock said tibial tray to said bearing component. a lateral jaw (157F, 157I) having an anterior end, a medial jaw (155F, 155I) having an anterior end, and said anterior end of said lateral jaw spaced apart from said anterior end of said medial jaw, said two-pronged boss lockingly engageable with said notch along said offset axis angle to lock said tibial tray to said bearing component.