US Patent 7967181 Rotary knife cutting systems

There are disclosed rotary cutting systems for use with circular surgical stapling devices. The rotary cutting systems generally include a circular knife blade and a mainspring for imparting rotary motion to the circular knife blade. A latch mechanism is provided to maintain the knife blade on a linear travel path during a first predetermined distance and to release the circular knife blade for rotation due to the bias of the mainspring along a second predetermine distance. The circular knife blade may be rotated by the mainspring itself or, in an alternative embodiment, may be driven by frictional engagement with a rotational hammer.