An orthopedic reamer cutting tool is disclosed. The reamer is constructed having a hemispherical cutting shell that extends from an equatorial base to an apex. A plurality of cutting teeth, each having a primary tissue cutting surface, extend from the exterior surface of the cutting shell. A plurality of retractable blades, each having a secondary tissue cutting surface, are supported on a rotatable cam positioned at the base of the shell. Rotation of the cam in one of a clockwise or counterclockwise direction causes the retractable blades to extend through respective slits that extend through the thickness of the reamer shell. Rotation of the cam in the opposite direction causes the retractable blades to retract through the slits, back into the interior of the shell.