Blade type rotatable surgical cutting instrument with improved cutter blade wear

Claim 1

A surgical instrument for cutting tissue comprising a first tubular member having a tapered end portion, said first tubular member formed with an opening therein for the tissue to enter to be cut, said first tubular member also formed with a shearing surface around at least a portion of the opening, a cutting tool within said tubular member, said cutting tool including a shaft having a cutter at one end and said cutter having a body which is tapered with a first taper complementary to the tapered end portion of said first tubular member, said body having at least one cutting surface formed thereon, means engaging said shaft for turning said cutting tool, means for bringing the cutting surface of the cutter body into positive engagement with the inner surface of said tubular member in the area of said shearing surface, said cutter body cutting surface and said opening shearing surface providing a shearing action on the tissue in said opening as the cutter cutting surface sweeps across the opening, said cutter body including at least one supporting surface, said supporting surface being at least a band extending straight and longitudinally of the cutter body along the direction of the shaft for engaging the inner surface of said tubular member and having a second taper such that said supporting surface increases in width going from said end of said first tubular member towards said shaft whereby the stress on the cutter body is controlled along its length.