A surgical cutting instrument for cutting tissue includes an outer cannula with a cutting opening and a cutting member within the cannula. The cutting member is connected to a source of reciprocation, and as the cutting member reciprocates the cutting member head is guided by a sloped member within the cannula to essentially a zero clearance position relative to a cutting edge of the cutting opening of the cannula. The instrument cleanly severs tissue extending through the cutting opening into the outer cannula.