Patent ID: 7597699

Claim:
A motorized surgical handpiece for driving a surgical tool to perform a cutting operation on anatomical tissue at a surgical site, said handpiece comprising a housing enclosing an interior; a motor disposed in said interior and having a front end and a back end; an output shaft disposed in said interior for being rotatably driven by said motor, said output shaft having a forward end portion extending forwardly beyond said front end of said motor, a rearward end portion extending rearwardly beyond said back end of said motor, and a longitudinal bore extending entirely through said output shaft for receiving a shank of a surgical tool to be driven in rotation by said output shaft; a forward labyrinth seal including a forward labyrinth seal rotor component attached to said forward end portion of said output shaft for rotation with said output shaft and a forward labyrinth seal stator component having an opening therethrough rotatably receiving said forward labyrinth seal rotor component with there being a labyrinthine clearance between said forward labyrinth seal rotor component and said forward labyrinth seal stator component, said clearance of said forward labyrinth seal being in communication with said interior and with the environment exterior of said housing; a rearward labyrinth seal including a rearward labyrinth seal rotor component attached to said rearward end portion of said output shaft for rotation with said output shaft, and a rearward labyrinth seal stator component having an opening therethrough rotatably receiving said rearward labyrinth seal rotor component with there being a labyrinthine clearance between said rearward labyrinth seal rotor component and said rearward labyrinth seal stator component, said clearance of said rearward labyrinth seal being in communication with said interior and with the environment exterior of said housing; means for supplying pressurized air to said clearances to flow in a direction away from said motor and toward the environment exterior of said housing; and a continuous lumen extending longitudinally entirely through said housing and formed in part by said bore of said output shaft.