A loading unit includes a staple cartridge assembly, an anvil assembly, and an anvil hook assembly. The anvil assembly has an opening defined therethrough, and the anvil hook assembly includes an anvil hook disposed within the opening of the anvil assembly and a pivot pin extending through the anvil hook and the anvil assembly. The anvil hook is pivotable with respect to the anvil assembly about the pivot pin between a loading position and a loaded position. The loading unit may further include a surgical buttress assembly including a cartridge buttress releasably attached to the staple cartridge assembly, an anvil buttress releasably attachable to the anvil assembly by the anvil hook, and a connecting member interconnecting the cartridge and anvil buttresses.