one of several instruments similarly suited for surgical activity the drive shaft 34 rotates to dispose a first cutting edge 124 2 of the inner cutting member 14 to engage a first cutting edge 122 1 of the outer cutting member 12 and disposes a second cutting edge 124 1 of the inner cutting member 14 to engage the second cutting edge 122 2 of the outer cutting member in an alternating manner as disclosed at step 305 upon initial insertion rotation of the drive shaft 34 determines the selected subset e g 114 or 114 u2032 by a degree of rotational oscillation and an angular position of the cutting edge 124 124 u2032 on an annular surface of the cylindrical members 14 as depicted at step 306 initial rotation will bring the cutting member having the multiple cutting windows 14 shown into alignment with the other cutting member having a single window 12 in the example shown thus at least one of the cylindrical members 14 includes a plurality of opposed pairs 124 1 124 2 and 124 u2032 1 124 u2032 2 of the cutting edges defined by a cutout 114 and 114 u2032 in an annular surface of the cylindrical member 14 such that the cutout is longitudinally parallel to the rotational axis 110 forming a substantially parallel pair of cutting edges defined by the rectangular cutout as shown at step 307 this orientation provides that the cutting edges 124 are substantially parallel to.