Surgical instrument with distal suction capability

A surgical instrument comprising:

• an outer cutting blade having a tubular body with a proximal end and a 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;
• and
• a suction conduit attached to and slidably disposed over the outer cutting blade before the surgical instrument is inserted into a patient, the suction conduit being slidably movable along the outer cutting blade between a retracted position, at which the suction conduit does not cover the cutting window of the outer cutting blade, and an extended position at which the suction conduit covers the cutting window of the outer cutting blade and a distal end of the suction conduit is located distally beyond the cutting window of the outer cutting blade, the suction conduit including a suction inlet at the distal end of the suction conduit,
• wherein the inner and outer cutting blades are configured such that when the inner and outer cutting blades are oriented with their cutting windows in alignment, and the suction conduit is in the extended position, a first gap exists between an inner surface of the suction conduit and a distal-most edge of the aligned cutting windows and a second gap, smaller than the first gap, exists between the inner surface of the suction conduit and an outermost surface of the tubular body of the outer cutting blade on a side of the outer cutting blade opposite from the aligned cutting windows, such that fluid flows through the suction inlet, the first gap and the aligned cutting windows when a vacuum is applied through an internal bore of the inner cutting blade.