US Patent 10478188 Implantable layer comprising a constricted configuration

A staple cartridge assembly is disclosed which comprises a cartridge body and an implantable layer. The implantable layer includes fibers comprised of a first material and a second material. The first material and the second material have different glass transition temperatures. After the fibers comprised of the first material and the second material have been intermixed or interwoven, the layer is exposed to a temperature which exceeds the lower of the two glass transition temperatures. This heating process causes the layer to constrict and increase in thickness. The layer, when implanted, can compensate for variations in tissue thickness within the staples.