Stapler cartridges and surgical apparatus that include a stapler cartridge can include a knife that retracts into the stapler cartridge after cutting stapled tissue to prevent an operator being cut by the knife during replacement of the used stapler cartridge with a new stapler cartridge. A stapler cartridge includes a staple pushing shuttle, a knife member slidably coupled with the staple pushing shuttle, and a cartridge body. The staple pushing shuttle is slidably coupled to the cartridge body. The cartridge body includes a guide track engaged by the knife member and configured so that a cutting blade of the knife member protrudes from the cartridge body during a first portion of a distal movement of the staple pushing shuttle and the cutting blade is retracted into the cartridge body during a second portion of the distal movement of the staple pushing shuttle.