A system comprising, at least one see-through optical head mounted display , and at least one processing unit coupled to or included in the at least one see-through optical head mounted display; wherein the at least one processing unit is configured to generate a virtual surgical guide in relationship to a surface of a physical joint at a predetermined position, predetermined orientation, or a combination thereof, wherein the virtual surgical guide is displayed by the at least one see-through optical head mounted display, wherein the virtual surgical guide is a virtual surgical plane indicating the predetermined position, predetermined orientation, or the combination thereof for aligning a physical saw blade, wherein the at least one processing unit is configured to display, by the at least one see-through optical head mounted display, at the predetermined position, predetermined orientation or combination thereof, the virtual surgical guide onto the surface of the physical joint visible directly through the see-through optical head mounted display, so as to superimpose the virtual surgical guide onto the surface of the physical joint to allow superimposition and alignment between the physical saw blade and the virtual surgical guide, and wherein the physical saw blade is configured to perform a bone cut of the physical joint. at least one see-through optical head mounted display , and at least one processing unit coupled to or included in the at least one see-through optical head mounted display; wherein the at least one processing unit is configured to generate a virtual surgical guide in relationship to a surface of a physical joint at a predetermined position, predetermined orientation, or a combination thereof, wherein the virtual surgical guide is displayed by the at least one see-through optical head mounted display, wherein the virtual surgical guide is a virtual surgical plane indicating the predetermined position, predetermined orientation, or the combination thereof for aligning a physical saw blade, wherein the at least one processing unit is configured to display, by the at least one see-through optical head mounted display, at the predetermined position, predetermined orientation or combination thereof, the virtual surgical guide onto the surface of the physical joint visible directly through the see-through optical head mounted display, so as to superimpose the virtual surgical guide onto the surface of the physical joint to allow superimposition and alignment between the physical saw blade and the virtual surgical guide, and wherein the physical saw blade is configured to perform a bone cut of the physical joint. wherein the at least one processing unit is configured to generate a virtual surgical guide in relationship to a surface of a physical joint at a predetermined position, predetermined orientation, or a combination thereof, wherein the virtual surgical guide is displayed by the at least one see-through optical head mounted display, wherein the virtual surgical guide is a virtual surgical plane indicating the predetermined position, predetermined orientation, or the combination thereof for aligning a physical saw blade, wherein the at least one processing unit is configured to display, by the at least one see-through optical head mounted display, at the predetermined position, predetermined orientation or combination thereof, the virtual surgical guide onto the surface of the physical joint visible directly through the see-through optical head mounted display, so as to superimpose the virtual surgical guide onto the surface of the physical joint to allow superimposition and alignment between the physical saw blade and the virtual surgical guide, and wherein the physical saw blade is configured to perform a bone cut of the physical joint. <EOS>