A surgical instrument comprising: an outer cutting blade having a tubular body with a proximal end and an open distal end , a cutting window disposed at a side of the outer cutting blade near the distal end; an inner cutting blade having a tubular body with a proximal end and a distal end, a cutting window disposed at a side of the inner cutting blade near the distal end, the inner cutting blade rotatably disposed inside of the outer cutting blade such that the surgical instrument cuts tissue by rotating the inner cutting blade within the outer cutting blade while a vacuum is applied through an internal bore of the inner cutting blade to draw the tissue into the cutting windows of the outer and inner cutting blades and sever the tissue by rotation of the inner cutting blade ; the distal end of the inner cutting blade including a suction aperture that remains in fluid communication with the open distal end of the outer cutting blade as the inner cutting blade rotates, wherein the surgical instrument can be used as a suction tool by applying the vacuum through the internal bore of the inner cutting blade while the inner cutting blade is stopped from rotating with the cutting windows of the outer and inner cutting blades misaligned with each other so that the vacuum is applied through the open distal end of the outer cutting blade and the suction aperture of the inner cutting blade , wherein the open distal end of the outer cutting blade is a suction opening , wherein an open suction passage defined by the suction opening and the suction aperture exists between the internal bore and an area external of the surgical instrument both when the inner cutting blade does not rotate, and when the inner cutting blade rotates, characterized in that an area of the suction opening in the outer cutting blade is smaller than an area of the suction aperture in the inner cutting blade to avoid pinching of tissue between the suction opening and the suction aperture . an outer cutting blade having a tubular body with a proximal end and an open distal end , a cutting window disposed at a side of the outer cutting blade near the distal end; an inner cutting blade having a tubular body with a proximal end and a distal end, a cutting window disposed at a side of the inner cutting blade near the distal end, the inner cutting blade rotatably disposed inside of the outer cutting blade such that the surgical instrument cuts tissue by rotating the inner cutting blade within the outer cutting blade while a vacuum is applied through an internal bore of the inner cutting blade to draw the tissue into the cutting windows of the outer and inner cutting blades and sever the tissue by rotation of the inner cutting blade ; the distal end of the inner cutting blade including a suction aperture that remains in fluid communication with the open distal end of the outer cutting blade as the inner cutting blade rotates, wherein the surgical instrument can be used as a suction tool by applying the vacuum through the internal bore of the inner cutting blade while the inner cutting blade is stopped from rotating with the cutting windows of the outer and inner cutting blades misaligned with each other so that the vacuum is applied through the open distal end of the outer cutting blade and the suction aperture of the inner cutting blade , wherein the open distal end of the outer cutting blade is a suction opening , wherein an open suction passage defined by the suction opening and the suction aperture exists between the internal bore and an area external of the surgical instrument both when the inner cutting blade does not rotate, and when the inner cutting blade rotates, characterized in that an area of the suction opening in the outer cutting blade is smaller than an area of the suction aperture in the inner cutting blade to avoid pinching of tissue between the suction opening and the suction aperture . <EOS>