A rongeur including: a cutting unit (240, 240a, 240b, 240c, 240d) that consists of an outer tube (244, 244a, 244b, 244c) and a cutting implement that is slidably disposed within the outer tube, the outer tube and cutting implement each having a distal end; a body; a mounting assembly (190, 216, 250, 252) attached to at least one of the body or the cutting unit outer tube for removably holding the outer tube to the body; a spindle rotatably disposed in said body, said spindle configured to engage the cutting unit cutter so that the cutting implement rotates with the spindle, wherein the spindle further includes a feature for holding the cutting unit cutting implement to the spindle so that, when the cutting implement is moved longitudinally relative to said spindle, the spindle is able to simultaneously rotate the cutting implement with the spindle; a power source connected to the spindle for rotating the spindle; and a cutting implement advancement/retraction assembly (150, 180) moveably attached to the body that releasably engages the cutting unit cutting implement and that is configured to, upon actuation, longitudinally move the cutting implement relative to the spindle so that the distal end of the cutting implement can be extended towards and retracted away from the distal end of the outer tube, characterized in that: the cutting implement (302, 303) of the cutting unit is a cutting tube that at an open distal end thereof is formed to have a cutting edge; the outer tube of the cutting unit is formed with a notch proximal to a distal end of the outer tube through which tissue enters the outer tube, wherein distal to the notch the outer tube has a face plate (272, 273) towards which the cutting tube is movable so that the cutting edge of the cutting tube acts against and cuts tissue that extends through the notch into the outer tube; and the cutting tube is configured so that a suction source can draw the excised tissue through the cutting tube. a cutting unit (240, 240a, 240b, 240c, 240d) that consists of an outer tube (244, 244a, 244b, 244c) and a cutting implement that is slidably disposed within the outer tube, the outer tube and cutting implement each having a distal end; a body; a mounting assembly (190, 216, 250, 252) attached to at least one of the body or the cutting unit outer tube for removably holding the outer tube to the body; a spindle rotatably disposed in said body, said spindle configured to engage the cutting unit cutter so that the cutting implement rotates with the spindle, wherein the spindle further includes a feature for holding the cutting unit cutting implement to the spindle so that, when the cutting implement is moved longitudinally relative to said spindle, the spindle is able to simultaneously rotate the cutting implement with the spindle; a power source connected to the spindle for rotating the spindle; and a cutting implement advancement/retraction assembly (150, 180) moveably attached to the body that releasably engages the cutting unit cutting implement and that is configured to, upon actuation, longitudinally move the cutting implement relative to the spindle so that the distal end of the cutting implement can be extended towards and retracted away from the distal end of the outer tube, characterized in that: the cutting implement (302, 303) of the cutting unit is a cutting tube that at an open distal end thereof is formed to have a cutting edge; the outer tube of the cutting unit is formed with a notch proximal to a distal end of the outer tube through which tissue enters the outer tube, wherein distal to the notch the outer tube has a face plate (272, 273) towards which the cutting tube is movable so that the cutting edge of the cutting tube acts against and cuts tissue that extends through the notch into the outer tube; and the cutting tube is configured so that a suction source can draw the excised tissue through the cutting tube. the cutting implement (302, 303) of the cutting unit is a cutting tube that at an open distal end thereof is formed to have a cutting edge; the outer tube of the cutting unit is formed with a notch proximal to a distal end of the outer tube through which tissue enters the outer tube, wherein distal to the notch the outer tube has a face plate (272, 273) towards which the cutting tube is movable so that the cutting edge of the cutting tube acts against and cuts tissue that extends through the notch into the outer tube; and the cutting tube is configured so that a suction source can draw the excised tissue through the cutting tube.