A tissue resecting instrument includes an end effector assembly having aproximalhub housing, a retainer cap extending proximally therefrom, an elongated outershaftextending distally from the proximal hub housing, an inner cutting shaftrotatably disposedwithin the elongated outer shaft, and an inner core drive assembly thatincludes a proximaldriver and a distal driver. The distal driver is coupled to the inner cuttingshaft such thatrotation of the distal driver rotates the inner cutting shaft relative to theelongated outer shaft.The proximal driver is slidable relative to the distal drive between a more-proximal positionwherein the proximal driver is engaged with the retainer cap to rotationallyfix the proximaldriver, thereby rotationally locking the inner cutting shaft, and a more-distal position whereinthe proximal driver is disengaged from the retainer cap permitting rotationthereof therebypermitting rotation of the inner cutting shaft.
